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When shared pages are being converted to private during kdump, additional
checks are performed. They include handling the case of a GHCB page being
contained within a huge page.
Currently, this check incorrectly skips a page just below the GHCB page from
being transitioned back to private during kdump preparation.
This skipped page causes a 0x404 #VC exception when it is accessed later while
dumping guest memory for vmcore generation.
Correct the range to be checked for GHCB contained in a huge page. Also,
ensure that the skipped huge page containing the GHCB page is transitioned
back to private by applying the correct address mask later when changing GHCBs
to private at end of kdump preparation.
[ bp: Massage commit message. ]
Fixes: 3074152e56c9 ("x86/sev: Convert shared memory back to private on kexec")
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Srikanth Aithal <sraithal@amd.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20250506183529.289549-1-Ashish.Kalra@amd.com
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When kdump is running makedumpfile to generate vmcore and dump SNP guest
memory it touches the VMSA page of the vCPU executing kdump.
It then results in unrecoverable #NPF/RMP faults as the VMSA page is
marked busy/in-use when the vCPU is running and subsequently a causes
guest softlockup/hang.
Additionally, other APs may be halted in guest mode and their VMSA pages
are marked busy and touching these VMSA pages during guest memory dump
will also cause #NPF.
Issue AP_DESTROY GHCB calls on other APs to ensure they are kicked out
of guest mode and then clear the VMSA bit on their VMSA pages.
If the vCPU running kdump is an AP, mark it's VMSA page as offline to
ensure that makedumpfile excludes that page while dumping guest memory.
Fixes: 3074152e56c9 ("x86/sev: Convert shared memory back to private on kexec")
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Srikanth Aithal <sraithal@amd.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20250428214151.155464-1-Ashish.Kalra@amd.com
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Introduce pm_suspend_in_progress() to be used for checking if a system-
wide suspend or resume transition is in progress, instead of comparing
pm_suspend_target_state directly to PM_SUSPEND_ON, and use it where
applicable.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Raag Jadav <raag.jadav@intel.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/2020901.PYKUYFuaPT@rjwysocki.net
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Conflicts:
Documentation/admin-guide/hw-vuln/index.rst
arch/x86/include/asm/cpufeatures.h
arch/x86/kernel/alternative.c
arch/x86/kernel/cpu/bugs.c
arch/x86/kernel/cpu/common.c
drivers/base/cpu.c
include/linux/cpu.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Conflicts:
arch/x86/boot/startup/sme.c
arch/x86/coco/sev/core.c
arch/x86/kernel/fpu/core.c
arch/x86/kernel/fpu/xstate.c
Semantic conflict:
arch/x86/include/asm/sev-internal.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Conflicts:
arch/x86/mm/numa.c
arch/x86/mm/pgtable.c
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Conflicts:
arch/x86/kernel/cpu/bugs.c
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Prepare to resolve conflicts with an upstream series of fixes that conflict
with pending x86 changes:
6f5bf947bab0 Merge tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Instead of calling pfn_valid() separately for every single PFN in the
range, use for_each_valid_pfn() and only look at the ones which are.
Link: https://lkml.kernel.org/r/20250423133821.789413-6-dwmw2@infradead.org
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Ruihan Li <lrh2000@pku.edu.cn>
Cc: Will Deacon <will@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Add ARCH_SUPPORTS_KEXEC_HANDOVER for 64 bits to allow enabling of
KEXEC_HANDOVER configuration option.
Link: https://lkml.kernel.org/r/20250509074635.3187114-15-changyuanl@google.com
Signed-off-by: Alexander Graf <graf@amazon.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Co-developed-by: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Gowans <jgowans@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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During kexec handover (KHO) memory contains data that should be preserved
and this data would be consumed by kexec'ed kernel.
To make sure that the preserved memory is not overwritten, KHO uses
"scratch regions" to bootstrap kexec'ed kernel. These regions are
guaranteed to not have any memory that KHO would preserve and are used as
the only memory the kernel sees during the early boot.
The scratch regions are passed in the setup_data by the first kernel with
other KHO parameters. If the setup_data contains the KHO parameters,
limit randomization to scratch areas only to make sure preserved memory
won't get overwritten.
Since all the pointers in setup_data are represented by u64, they require
double casting (first to unsigned long and then to the actual pointer
type) to compile on 32-bits. This looks goofy out of context, but it is
unfortunately the way that this is handled across the tree. There are at
least a dozen instances of casting like this.
Link: https://lkml.kernel.org/r/20250509074635.3187114-14-changyuanl@google.com
Signed-off-by: Alexander Graf <graf@amazon.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Co-developed-by: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Gowans <jgowans@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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KHO kernels are special and use only scratch memory for memblock
allocations, but memory below 1M is ignored by kernel after early boot and
cannot be naturally marked as scratch.
To allow allocation of the real-mode trampoline and a few (if any) other
very early allocations from below 1M forcibly mark the memory below 1M as
scratch.
After real mode trampoline is allocated, clear that scratch marking.
Link: https://lkml.kernel.org/r/20250509074635.3187114-13-changyuanl@google.com
Signed-off-by: Alexander Graf <graf@amazon.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Co-developed-by: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Gowans <jgowans@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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kexec handover (KHO) creates a metadata that the kernels pass between each
other during kexec. This metadata is stored in memory and kexec image
contains a (physical) pointer to that memory.
In addition, KHO keeps "scratch regions" available for kexec: physically
contiguous memory regions that are guaranteed to not have any memory that
KHO would preserve. The new kernel bootstraps itself using the scratch
regions and sets all handed over memory as in use. When subsystems that
support KHO initialize, they introspect the KHO metadata, restore
preserved memory regions, and retrieve their state stored in the preserved
memory.
Enlighten x86 kexec-file and boot path about the KHO metadata and make
sure it gets passed along to the next kernel.
Link: https://lkml.kernel.org/r/20250509074635.3187114-12-changyuanl@google.com
Signed-off-by: Alexander Graf <graf@amazon.com>
Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Co-developed-by: Changyuan Lyu <changyuanl@google.com>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Gowans <jgowans@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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memblock_reserve() does not distinguish memory used by firmware from
memory used by kernel.
The distinction is nice to have for accounting of early memory allocations
and reservations, but it is essential for kexec handover (kho) to know how
much memory kernel consumes during boot.
Use memblock_reserve_kern() to reserve kernel memory, such as kernel
image, initrd and setup data.
Link: https://lkml.kernel.org/r/20250509074635.3187114-11-changyuanl@google.com
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ashish Kalra <ashish.kalra@amd.com>
Cc: Ben Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Gowans <jgowans@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Yadav <ptyadav@amazon.de>
Cc: Rob Herring <robh@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The resctrl file system code needs to know how many region tags
are supported. Parse the ACPI MRRM table and save the max_mem_region
value.
Provide a function for resctrl to collect that value.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://patch.msgid.link/20250505173819.419271-2-tony.luck@intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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When suspending, save_processor_state() calls mtrr_save_fixed_ranges()
to save fixed-range MTRRs.
On platforms without fixed-range MTRRs like the ACRN hypervisor which
has removed fixed-range MTRR emulation, accessing these MSRs will
trigger an unchecked MSR access error. Make sure fixed-range MTRRs are
supported before access to prevent such error.
Since mtrr_state.have_fixed is only set when MTRRs are present and
enabled, checking the CPU feature flag in mtrr_save_fixed_ranges() is
unnecessary.
Fixes: 3ebad5905609 ("[PATCH] x86: Save and restore the fixed-range MTRRs of the BSP when suspending")
Signed-off-by: Jiaqing Zhao <jiaqing.zhao@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250509170633.3411169-2-jiaqing.zhao@linux.intel.com
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Add explicit array bounds to the function prototypes for the parameters
that didn't already get handled by the conversion to use chacha_state:
- chacha_block_*():
Change 'u8 *out' or 'u8 *stream' to u8 out[CHACHA_BLOCK_SIZE].
- hchacha_block_*():
Change 'u32 *out' or 'u32 *stream' to u32 out[HCHACHA_OUT_WORDS].
- chacha_init():
Change 'const u32 *key' to 'const u32 key[CHACHA_KEY_WORDS]'.
Change 'const u8 *iv' to 'const u8 iv[CHACHA_IV_SIZE]'.
No functional changes. This just makes it clear when fixed-size arrays
are expected.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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The ChaCha state matrix is 16 32-bit words. Currently it is represented
in the code as a raw u32 array, or even just a pointer to u32. This
weak typing is error-prone. Instead, introduce struct chacha_state:
struct chacha_state {
u32 x[16];
};
Convert all ChaCha and HChaCha functions to use struct chacha_state.
No functional changes.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Page table pages are normally freed using the appropriate helper for the
given page table level. On x86, pud_free_pmd_page() and
pmd_free_pte_page() are an exception to the rule: they call free_page()
directly.
Constructor/destructor calls are about to be introduced for kernel PTEs.
To avoid missing dtor calls in those helpers, free the PTE pages using
pte_free_kernel() instead of free_page().
While at it also use pmd_free() instead of calling pagetable_dtor()
explicitly at the PMD level.
Link: https://lkml.kernel.org/r/20250408095222.860601-3-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "Always call constructor for kernel page tables", v2.
There has been much confusion around exactly when page table
constructors/destructors (pagetable_*_[cd]tor) are supposed to be called.
They were initially introduced for user PTEs only (to support split page
table locks), then at the PMD level for the same purpose. Accounting was
added later on, starting at the PTE level and then moving to higher levels
(PMD, PUD). Finally, with my earlier series "Account page tables at all
levels" [1], the ctor/dtor is run for all levels, all the way to PGD.
I thought this was the end of the story, and it hopefully is for user
pgtables, but I was wrong for what concerns kernel pgtables. The current
situation there makes very little sense:
* At the PTE level, the ctor/dtor is not called (at least in the generic
implementation). Specific helpers are used for kernel pgtables at this
level (pte_{alloc,free}_kernel()) and those have never called the
ctor/dtor, most likely because they were initially irrelevant in the
kernel case.
* At all other levels, the ctor/dtor is normally called. This is
potentially wasteful at the PMD level (more on that later).
This series aims to ensure that the ctor/dtor is always called for kernel
pgtables, as it already is for user pgtables. Besides consistency, the
main motivation is to guarantee that ctor/dtor hooks are systematically
called; this makes it possible to insert hooks to protect page tables [2],
for instance. There is however an extra challenge: split locks are not
used for kernel pgtables, and it would therefore be wasteful to initialise
them (ptlock_init()).
It is worth clarifying exactly when split locks are used. They clearly
are for user pgtables, but as illustrated in commit 61444cde9170 ("ARM:
8591/1: mm: use fully constructed struct pages for EFI pgd allocations"),
they also are for special page tables like efi_mm. The one case where
split locks are definitely unused is pgtables owned by init_mm; this is
consistent with the behaviour of apply_to_pte_range().
The approach chosen in this series is therefore to pass the mm associated
to the pgtables being constructed to pagetable_{pte,pmd}_ctor() (patch 1),
and skip ptlock_init() if mm == &init_mm (patch 3 and 7). This makes it
possible to call the PTE ctor/dtor from pte_{alloc,free}_kernel() without
unintended consequences (patch 3). As a result the accounting functions
are now called at all levels for kernel pgtables, and split locks are
never initialised.
In configurations where ptlocks are dynamically allocated (32-bit,
PREEMPT_RT, etc.) and ARCH_ENABLE_SPLIT_PMD_PTLOCK is selected, this
series results in the removal of a kmem_cache allocation for every kernel
PMD. Additionally, for certain architectures that do not use
<asm-generic/pgalloc.h> such as s390, the same optimisation occurs at the
PTE level.
===
Things get more complicated when it comes to special pgtable allocators
(patch 8-12). All architectures need such allocators to create initial
kernel pgtables; we are not concerned with those as the ctor cannot be
called so early in the boot sequence. However, those allocators may also
be used later in the boot sequence or during normal operations. There are
two main use-cases:
1. Mapping EFI memory: efi_mm (arm, arm64, riscv)
2. arch_add_memory(): init_mm
The ctor is already explicitly run (at the PTE/PMD level) in the first
case, as required for pgtables that are not associated with init_mm.
However the same allocators may also be used for the second use-case (or
others), and this is where it gets messy. Patch 1 calls the ctor with
NULL as mm in those situations, as the actual mm isn't available.
Practically this means that ptlocks will be unconditionally initialised.
This is fine on arm - create_mapping_late() is only used for the EFI
mapping. On arm64, __create_pgd_mapping() is also used by
arch_add_memory(); patch 8/9/11 ensure that ctors are called at all levels
with the appropriate mm. The situation is similar on riscv, but
propagating the mm down to the ctor would require significant refactoring.
Since they are already called unconditionally, this series leaves riscv
no worse off - patch 10 adds comments to clarify the situation.
From a cursory look at other architectures implementing arch_add_memory(),
s390 and x86 may also need a similar treatment to add constructor calls.
This is to be taken care of in a future version or as a follow-up.
===
The complications in those special pgtable allocators beg the question:
does it really make sense to treat efi_mm and init_mm differently in e.g.
apply_to_pte_range()? Maybe what we really need is a way to tell if an mm
corresponds to user memory or not, and never use split locks for non-user
mm's. Feedback and suggestions welcome!
This patch (of 12):
In preparation for calling constructors for all kernel page tables while
eliding unnecessary ptlock initialisation, let's pass down the associated
mm to the PTE/PMD level ctors. (These are the two levels where ptlocks
are used.)
In most cases the mm is already around at the point of calling the ctor so
we simply pass it down. This is however not the case for special page
table allocators:
* arch/arm/mm/mmu.c
* arch/arm64/mm/mmu.c
* arch/riscv/mm/init.c
In those cases, the page tables being allocated are either for standard
kernel memory (init_mm) or special page directories, which may not be
associated to any mm. For now let's pass NULL as mm; this will be refined
where possible in future patches.
No functional change in this patch.
Link: https://lore.kernel.org/linux-mm/20250103184415.2744423-1-kevin.brodsky@arm.com/ [1]
Link: https://lore.kernel.org/linux-hardening/20250203101839.1223008-1-kevin.brodsky@arm.com/ [2]
Link: https://lkml.kernel.org/r/20250408095222.860601-1-kevin.brodsky@arm.com
Link: https://lkml.kernel.org/r/20250408095222.860601-2-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> [s390]
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: <x86@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Last argument in effective_prot() is u64 assuming pxd_val() returned value
(all page table levels) is 64 bit. pxd_val() is very platform specific
and its type should not be assumed in generic MM.
Split effective_prot() into individual page table level specific callbacks
which accepts corresponding pxd_t argument instead and then the
subscribing platform (only x86) just derive pxd_val() from the entries as
required and proceed as earlier.
Link: https://lkml.kernel.org/r/20250407053113.746295-3-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm/ptdump: Drop assumption that pxd_val() is u64", v2.
Last argument passed down in note_page() is u64 assuming pxd_val()
returned value (all page table levels) is 64 bit - which might not be the
case going ahead when D128 page tables is enabled on arm64 platform.
Besides pxd_val() is very platform specific and its type should not be
assumed in generic MM. A similar problem exists for effective_prot(),
although it is restricted to x86 platform.
This series splits note_page() and effective_prot() into individual page
table level specific callbacks which accepts corresponding pxd_t page
table entry as an argument instead and later on all subscribing platforms
could derive pxd_val() from the table entries as required and proceed as
before.
Define ptdesc_t type which describes the basic page table descriptor
layout on arm64 platform. Subsequently all level specific pxxval_t
descriptors are derived from ptdesc_t thus establishing a common original
format, which can also be appropriate for page table entries, masks and
protection values etc which are used at all page table levels.
This patch (of 3):
Last argument passed down in note_page() is u64 assuming pxd_val()
returned value (all page table levels) is 64 bit - which might not be the
case going ahead when D128 page tables is enabled on arm64 platform.
Besides pxd_val() is very platform specific and its type should not be
assumed in generic MM.
Split note_page() into individual page table level specific callbacks
which accepts corresponding pxd_t argument instead and then subscribing
platforms just derive pxd_val() from the entries as required and proceed
as earlier.
Also add a note_page_flush() callback for flushing the last page table
page that was being handled earlier via level = -1.
Link: https://lkml.kernel.org/r/20250407053113.746295-1-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/20250407053113.746295-2-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Similar to syscall_set_arguments() that complements
syscall_get_arguments(), introduce syscall_set_nr() that complements
syscall_get_nr().
syscall_set_nr() is going to be needed along with syscall_set_arguments()
on all HAVE_ARCH_TRACEHOOK architectures to implement
PTRACE_SET_SYSCALL_INFO API.
Link: https://lkml.kernel.org/r/20250303112020.GD24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk> # mips
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This function is going to be needed on all HAVE_ARCH_TRACEHOOK
architectures to implement PTRACE_SET_SYSCALL_INFO API.
This partially reverts commit 7962c2eddbfe ("arch: remove unused function
syscall_set_arguments()") by reusing some of old syscall_set_arguments()
implementations.
[nathan@kernel.org: fix compile time fortify checks]
Link: https://lkml.kernel.org/r/20250408213131.GA2872426@ax162
Link: https://lkml.kernel.org/r/20250303112009.GC24170@strace.io
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk> [mips]
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexey Gladkov (Intel) <legion@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: anton ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Brian Cain <bcain@quicinc.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Davide Berardi <berardi.dav@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Eugene Syromyatnikov <evgsyr@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Renzo Davoi <renzo@cs.unibo.it>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russel King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Systems with hotplug may provide an advisement value on what the memblock
size should be. Probe this value when the rest of the configuration
values are considered.
The new heuristic is as follows
1) set_memory_block_size_order value if already set (cmdline param)
2) minimum block size if memory is less than large block limit
3) if no hotplug advice: Max block size if system is bare-metal,
otherwise use end of memory alignment.
4) if hotplug advice: lesser of advice and end of memory alignment.
Convert to cpu_feature_enabled() while at it.[1]
[1] https://lore.kernel.org/all/20241031103401.GBZyNdGQ-ZyXKyzC_z@fat_crate.local/
Link: https://lkml.kernel.org/r/20250127153405.3379117-3-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Suggested-by: Borislav Petkov <bp@alien8.de>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Bruno Faccini <bfaccini@nvidia.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haibo Xu <haibo1.xu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Robert Richter <rrichter@amd.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
There are now no callers of mk_huge_pmd() and mk_pmd(). Remove them.
Link: https://lkml.kernel.org/r/20250402181709.2386022-12-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Move the shadow stack check to pfn_pte() which lets us use the common
definition of mk_pte().
Link: https://lkml.kernel.org/r/20250402181709.2386022-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 ITS mitigation from Dave Hansen:
"Mitigate Indirect Target Selection (ITS) issue.
I'd describe this one as a good old CPU bug where the behavior is
_obviously_ wrong, but since it just results in bad predictions it
wasn't wrong enough to notice. Well, the researchers noticed and also
realized that thus bug undermined a bunch of existing indirect branch
mitigations.
Thus the unusually wide impact on this one. Details:
ITS is a bug in some Intel CPUs that affects indirect branches
including RETs in the first half of a cacheline. Due to ITS such
branches may get wrongly predicted to a target of (direct or indirect)
branch that is located in the second half of a cacheline. Researchers
at VUSec found this behavior and reported to Intel.
Affected processors:
- Cascade Lake, Cooper Lake, Whiskey Lake V, Coffee Lake R, Comet
Lake, Ice Lake, Tiger Lake and Rocket Lake.
Scope of impact:
- Guest/host isolation:
When eIBRS is used for guest/host isolation, the indirect branches
in the VMM may still be predicted with targets corresponding to
direct branches in the guest.
- Intra-mode using cBPF:
cBPF can be used to poison the branch history to exploit ITS.
Realigning the indirect branches and RETs mitigates this attack
vector.
- User/kernel:
With eIBRS enabled user/kernel isolation is *not* impacted by ITS.
- Indirect Branch Prediction Barrier (IBPB):
Due to this bug indirect branches may be predicted with targets
corresponding to direct branches which were executed prior to IBPB.
This will be fixed in the microcode.
Mitigation:
As indirect branches in the first half of cacheline are affected, the
mitigation is to replace those indirect branches with a call to thunk that
is aligned to the second half of the cacheline.
RETs that take prediction from RSB are not affected, but they may be
affected by RSB-underflow condition. So, RETs in the first half of
cacheline are also patched to a return thunk that executes the RET aligned
to second half of cacheline"
* tag 'its-for-linus-20250509' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
selftest/x86/bugs: Add selftests for ITS
x86/its: FineIBT-paranoid vs ITS
x86/its: Use dynamic thunks for indirect branches
x86/ibt: Keep IBT disabled during alternative patching
mm/execmem: Unify early execmem_cache behaviour
x86/its: Align RETs in BHB clear sequence to avoid thunking
x86/its: Add support for RSB stuffing mitigation
x86/its: Add "vmexit" option to skip mitigation on some CPUs
x86/its: Enable Indirect Target Selection mitigation
x86/its: Add support for ITS-safe return thunk
x86/its: Add support for ITS-safe indirect thunk
x86/its: Enumerate Indirect Target Selection (ITS) bug
Documentation: x86/bugs/its: Add ITS documentation
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 IBTI mitigation from Dave Hansen:
"Mitigate Intra-mode Branch History Injection via classic BFP programs
This adds the branch history clearing mitigation to cBPF programs for
x86. Intra-mode BHI attacks via cBPF a.k.a IBTI-History was reported
by researchers at VUSec.
For hardware that doesn't support BHI_DIS_S, the recommended
mitigation is to run the short software sequence followed by the IBHF
instruction after cBPF execution. On hardware that does support
BHI_DIS_S, enable BHI_DIS_S and execute the IBHF after cBPF execution.
The Indirect Branch History Fence (IBHF) is a new instruction that
prevents indirect branch target predictions after the barrier from
using branch history from before the barrier while BHI_DIS_S is
enabled. On older systems this will map to a NOP. It is recommended to
add this fence at the end of the cBPF program to support VM migration.
This instruction is required on newer parts with BHI_NO to fully
mitigate against these attacks.
The current code disables the mitigation for anything running with the
SYS_ADMIN capability bit set. The intention was not to waste time
mitigating a process that has access to anything it wants anyway"
* tag 'ibti-hisory-for-linus-2025-05-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/bhi: Do not set BHI_DIS_S in 32-bit mode
x86/bpf: Add IBHF call at end of classic BPF
x86/bpf: Call branch history clearing sequence on exit
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Pull KVM fixes from Paolo Bonzini:
"ARM:
- Avoid use of uninitialized memcache pointer in user_mem_abort()
- Always set HCR_EL2.xMO bits when running in VHE, allowing
interrupts to be taken while TGE=0 and fixing an ugly bug on
AmpereOne that occurs when taking an interrupt while clearing the
xMO bits (AC03_CPU_36)
- Prevent VMMs from hiding support for AArch64 at any EL virtualized
by KVM
- Save/restore the host value for HCRX_EL2 instead of restoring an
incorrect fixed value
- Make host_stage2_set_owner_locked() check that the entire requested
range is memory rather than just the first page
RISC-V:
- Add missing reset of smstateen CSRs
x86:
- Forcibly leave SMM on SHUTDOWN interception on AMD CPUs to avoid
causing problems due to KVM stuffing INIT on SHUTDOWN (KVM needs to
sanitize the VMCB as its state is undefined after SHUTDOWN,
emulating INIT is the least awful choice).
- Track the valid sync/dirty fields in kvm_run as a u64 to ensure KVM
KVM doesn't goof a sanity check in the future.
- Free obsolete roots when (re)loading the MMU to fix a bug where
pre-faulting memory can get stuck due to always encountering a
stale root.
- When dumping GHCB state, use KVM's snapshot instead of the raw GHCB
page to print state, so that KVM doesn't print stale/wrong
information.
- When changing memory attributes (e.g. shared <=> private), add
potential hugepage ranges to the mmu_invalidate_range_{start,end}
set so that KVM doesn't create a shared/private hugepage when the
the corresponding attributes will become mixed (the attributes are
commited *after* KVM finishes the invalidation).
- Rework the SRSO mitigation to enable BP_SPEC_REDUCE only when KVM
has at least one active VM. Effectively BP_SPEC_REDUCE when KVM is
loaded led to very measurable performance regressions for non-KVM
workloads"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: SVM: Set/clear SRSO's BP_SPEC_REDUCE on 0 <=> 1 VM count transitions
KVM: arm64: Fix memory check in host_stage2_set_owner_locked()
KVM: arm64: Kill HCRX_HOST_FLAGS
KVM: arm64: Properly save/restore HCRX_EL2
KVM: arm64: selftest: Don't try to disable AArch64 support
KVM: arm64: Prevent userspace from disabling AArch64 support at any virtualisable EL
KVM: arm64: Force HCR_EL2.xMO to 1 at all times in VHE mode
KVM: arm64: Fix uninitialized memcache pointer in user_mem_abort()
KVM: x86/mmu: Prevent installing hugepages when mem attributes are changing
KVM: SVM: Update dump_ghcb() to use the GHCB snapshot fields
KVM: RISC-V: reset smstateen CSRs
KVM: x86/mmu: Check and free obsolete roots in kvm_mmu_reload()
KVM: x86: Check that the high 32bits are clear in kvm_arch_vcpu_ioctl_run()
KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fix from Ingo Molnar:
"Fix a boot regression on very old x86 CPUs without CPUID support"
* tag 'x86-urgent-2025-05-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/microcode: Consolidate the loader enablement checking
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The GHCB_MSR_VMPL_REQ_LEVEL macro lacked parentheses around the bitmask
expression, causing the shift operation to bind too early. As a result,
when requesting VMPL1 (e.g., GHCB_MSR_VMPL_REQ_LEVEL(1)), incorrect
values such as 0x000000016 were generated instead of the intended
0x100000016 (the requested VMPL level is specified in GHCBData[39:32]).
Fix the precedence issue by grouping the masked value before applying
the shift.
[ bp: Massage commit message. ]
Fixes: 34ff65901735 ("x86/sev: Use kernel provided SVSM Calling Areas")
Signed-off-by: Seongman Lee <augustus92@kaist.ac.kr>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250511092329.12680-1-cloudlee1719@gmail.com
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc hotfixes from Andrew Morton:
"22 hotfixes. 13 are cc:stable and the remainder address post-6.14
issues or aren't considered necessary for -stable kernels.
About half are for MM. Five OCFS2 fixes and a few MAINTAINERS updates"
* tag 'mm-hotfixes-stable-2025-05-10-14-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (22 commits)
mm: fix folio_pte_batch() on XEN PV
nilfs2: fix deadlock warnings caused by lock dependency in init_nilfs()
mm/hugetlb: copy the CMA flag when demoting
mm, swap: fix false warning for large allocation with !THP_SWAP
selftests/mm: fix a build failure on powerpc
selftests/mm: fix build break when compiling pkey_util.c
mm: vmalloc: support more granular vrealloc() sizing
tools/testing/selftests: fix guard region test tmpfs assumption
ocfs2: stop quota recovery before disabling quotas
ocfs2: implement handshaking with ocfs2 recovery thread
ocfs2: switch osb->disable_recovery to enum
mailmap: map Uwe's BayLibre addresses to a single one
MAINTAINERS: add mm THP section
mm/userfaultfd: fix uninitialized output field for -EAGAIN race
selftests/mm: compaction_test: support platform with huge mount of memory
MAINTAINERS: add core mm section
ocfs2: fix panic in failed foilio allocation
mm/huge_memory: fix dereferencing invalid pmd migration entry
MAINTAINERS: add reverse mapping section
x86: disable image size check for test builds
...
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KVM x86 fixes for 6.15-rcN
- Forcibly leave SMM on SHUTDOWN interception on AMD CPUs to avoid causing
problems due to KVM stuffing INIT on SHUTDOWN (KVM needs to sanitize the
VMCB as its state is undefined after SHUTDOWN, emulating INIT is the
least awful choice).
- Track the valid sync/dirty fields in kvm_run as a u64 to ensure KVM
KVM doesn't goof a sanity check in the future.
- Free obsolete roots when (re)loading the MMU to fix a bug where
pre-faulting memory can get stuck due to always encountering a stale
root.
- When dumping GHCB state, use KVM's snapshot instead of the raw GHCB page
to print state, so that KVM doesn't print stale/wrong information.
- When changing memory attributes (e.g. shared <=> private), add potential
hugepage ranges to the mmu_invalidate_range_{start,end} set so that KVM
doesn't create a shared/private hugepage when the the corresponding
attributes will become mixed (the attributes are commited *after* KVM
finishes the invalidation).
- Rework the SRSO mitigation to enable BP_SPEC_REDUCE only when KVM has at
least one active VM. Effectively BP_SPEC_REDUCE when KVM is loaded led
to very measurable performance regressions for non-KVM workloads.
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Make the architecture-optimized CRC code do its CPU feature checks in
subsys_initcalls instead of arch_initcalls. This makes it consistent
with arch/*/lib/crypto/ and ensures that it runs after initcalls that
possibly could be a prerequisite for kernel-mode FPU, such as x86's
xfd_update_static_branch() and loongarch's init_euen_mask().
Note: as far as I can tell, x86's xfd_update_static_branch() isn't
*actually* needed for kernel-mode FPU. loongarch's init_euen_mask() is
needed to enable save/restore of the vector registers, but loongarch
doesn't yet have any CRC or crypto code that uses vector registers
anyway. Regardless, let's be consistent with arch/*/lib/crypto/ and
robust against any potential future dependency on an arch_initcall.
Link: https://lore.kernel.org/r/20250510035959.87995-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux
Pull rust fixes from Miguel Ojeda:
- Make CFI_AUTO_DEFAULT depend on !RUST or Rust >= 1.88.0
- Clean Rust (and Clippy) lints for the upcoming Rust 1.87.0 and 1.88.0
releases
- Clean objtool warning for the upcoming Rust 1.87.0 release by adding
one more noreturn function
* tag 'rust-fixes-6.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
x86/Kconfig: make CFI_AUTO_DEFAULT depend on !RUST or Rust >= 1.88
rust: clean Rust 1.88.0's `clippy::uninlined_format_args` lint
rust: clean Rust 1.88.0's warning about `clippy::disallowed_macros` configuration
rust: clean Rust 1.88.0's `unnecessary_transmutes` lint
rust: allow Rust 1.87.0's `clippy::ptr_eq` lint
objtool/rust: add one more `noreturn` Rust function for Rust 1.87.0
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FineIBT-paranoid was using the retpoline bytes for the paranoid check,
disabling retpolines, because all parts that have IBT also have eIBRS
and thus don't need no stinking retpolines.
Except... ITS needs the retpolines for indirect calls must not be in
the first half of a cacheline :-/
So what was the paranoid call sequence:
<fineibt_paranoid_start>:
0: 41 ba 78 56 34 12 mov $0x12345678, %r10d
6: 45 3b 53 f7 cmp -0x9(%r11), %r10d
a: 4d 8d 5b <f0> lea -0x10(%r11), %r11
e: 75 fd jne d <fineibt_paranoid_start+0xd>
10: 41 ff d3 call *%r11
13: 90 nop
Now becomes:
<fineibt_paranoid_start>:
0: 41 ba 78 56 34 12 mov $0x12345678, %r10d
6: 45 3b 53 f7 cmp -0x9(%r11), %r10d
a: 4d 8d 5b f0 lea -0x10(%r11), %r11
e: 2e e8 XX XX XX XX cs call __x86_indirect_paranoid_thunk_r11
Where the paranoid_thunk looks like:
1d: <ea> (bad)
__x86_indirect_paranoid_thunk_r11:
1e: 75 fd jne 1d
__x86_indirect_its_thunk_r11:
20: 41 ff eb jmp *%r11
23: cc int3
[ dhansen: remove initialization to false ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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ITS mitigation moves the unsafe indirect branches to a safe thunk. This
could degrade the prediction accuracy as the source address of indirect
branches becomes same for different execution paths.
To improve the predictions, and hence the performance, assign a separate
thunk for each indirect callsite. This is also a defense-in-depth measure
to avoid indirect branches aliasing with each other.
As an example, 5000 dynamic thunks would utilize around 16 bits of the
address space, thereby gaining entropy. For a BTB that uses
32 bits for indexing, dynamic thunks could provide better prediction
accuracy over fixed thunks.
Have ITS thunks be variable sized and use EXECMEM_MODULE_TEXT such that
they are both more flexible (got to extend them later) and live in 2M TLBs,
just like kernel code, avoiding undue TLB pressure.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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cfi_rewrite_callers() updates the fineIBT hash matching at the caller side,
but except for paranoid-mode it relies on apply_retpoline() and friends for
any ENDBR relocation. This could temporarily cause an indirect branch to
land on a poisoned ENDBR.
For instance, with para-virtualization enabled, a simple wrmsrl() could
have an indirect branch pointing to native_write_msr() who's ENDBR has been
relocated due to fineIBT:
<wrmsrl>:
push %rbp
mov %rsp,%rbp
mov %esi,%eax
mov %rsi,%rdx
shr $0x20,%rdx
mov %edi,%edi
mov %rax,%rsi
call *0x21e65d0(%rip) # <pv_ops+0xb8>
^^^^^^^^^^^^^^^^^^^^^^^
Such an indirect call during the alternative patching could #CP if the
caller is not *yet* adjusted for the new target ENDBR. To prevent a false
#CP, keep CET-IBT disabled until all callers are patched.
Patching during the module load does not need to be guarded by IBT-disable
because the module code is not executed until the patching is complete.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Early kernel memory is RWX, only at the end of early boot (before SMP)
do we mark things ROX. Have execmem_cache mirror this behaviour for
early users.
This avoids having to remember what code is execmem and what is not --
we can poke everything with impunity ;-) Also performance for not
having to do endless text_poke_mm switches.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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The software mitigation for BHI is to execute BHB clear sequence at syscall
entry, and possibly after a cBPF program. ITS mitigation thunks RETs in the
lower half of the cacheline. This causes the RETs in the BHB clear sequence
to be thunked as well, adding unnecessary branches to the BHB clear
sequence.
Since the sequence is in hot path, align the RET instructions in the
sequence to avoid thunking.
This is how disassembly clear_bhb_loop() looks like after this change:
0x44 <+4>: mov $0x5,%ecx
0x49 <+9>: call 0xffffffff81001d9b <clear_bhb_loop+91>
0x4e <+14>: jmp 0xffffffff81001de5 <clear_bhb_loop+165>
0x53 <+19>: int3
...
0x9b <+91>: call 0xffffffff81001dce <clear_bhb_loop+142>
0xa0 <+96>: ret
0xa1 <+97>: int3
...
0xce <+142>: mov $0x5,%eax
0xd3 <+147>: jmp 0xffffffff81001dd6 <clear_bhb_loop+150>
0xd5 <+149>: nop
0xd6 <+150>: sub $0x1,%eax
0xd9 <+153>: jne 0xffffffff81001dd3 <clear_bhb_loop+147>
0xdb <+155>: sub $0x1,%ecx
0xde <+158>: jne 0xffffffff81001d9b <clear_bhb_loop+91>
0xe0 <+160>: ret
0xe1 <+161>: int3
0xe2 <+162>: int3
0xe3 <+163>: int3
0xe4 <+164>: int3
0xe5 <+165>: lfence
0xe8 <+168>: pop %rbp
0xe9 <+169>: ret
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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When retpoline mitigation is enabled for spectre-v2, enabling
call-depth-tracking and RSB stuffing also mitigates ITS. Add cmdline option
indirect_target_selection=stuff to allow enabling RSB stuffing mitigation.
When retpoline mitigation is not enabled, =stuff option is ignored, and
default mitigation for ITS is deployed.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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Ice Lake generation CPUs are not affected by guest/host isolation part of
ITS. If a user is only concerned about KVM guests, they can now choose a
new cmdline option "vmexit" that will not deploy the ITS mitigation when
CPU is not affected by guest/host isolation. This saves the performance
overhead of ITS mitigation on Ice Lake gen CPUs.
When "vmexit" option selected, if the CPU is affected by ITS guest/host
isolation, the default ITS mitigation is deployed.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
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