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* kvm-arm64/writable-midr:
: Writable implementation ID registers, courtesy of Sebastian Ott
:
: Introduce a new capability that allows userspace to set the
: ID registers that identify a CPU implementation: MIDR_EL1, REVIDR_EL1,
: and AIDR_EL1. Also plug a hole in KVM's trap configuration where
: SMIDR_EL1 was readable at EL1, despite the fact that KVM does not
: support SME.
KVM: arm64: Fix documentation for KVM_CAP_ARM_WRITABLE_IMP_ID_REGS
KVM: arm64: Copy MIDR_EL1 into hyp VM when it is writable
KVM: arm64: Copy guest CTR_EL0 into hyp VM
KVM: selftests: arm64: Test writes to MIDR,REVIDR,AIDR
KVM: arm64: Allow userspace to change the implementation ID registers
KVM: arm64: Load VPIDR_EL2 with the VM's MIDR_EL1 value
KVM: arm64: Maintain per-VM copy of implementation ID regs
KVM: arm64: Set HCR_EL2.TID1 unconditionally
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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* kvm-arm64/pv-cpuid:
: Paravirtualized implementation ID, courtesy of Shameer Kolothum
:
: Big-little has historically been a pain in the ass to virtualize. The
: implementation ID (MIDR, REVIDR, AIDR) of a vCPU can change at the whim
: of vCPU scheduling. This can be particularly annoying when the guest
: needs to know the underlying implementation to mitigate errata.
:
: "Hyperscalers" face a similar scheduling problem, where VMs may freely
: migrate between hosts in a pool of heterogenous hardware. And yes, our
: server-class friends are equally riddled with errata too.
:
: In absence of an architected solution to this wart on the ecosystem,
: introduce support for paravirtualizing the implementation exposed
: to a VM, allowing the VMM to describe the pool of implementations that a
: VM may be exposed to due to scheduling/migration.
:
: Userspace is expected to intercept and handle these hypercalls using the
: SMCCC filter UAPI, should it choose to do so.
smccc: kvm_guest: Fix kernel builds for 32 bit arm
KVM: selftests: Add test for KVM_REG_ARM_VENDOR_HYP_BMAP_2
smccc/kvm_guest: Enable errata based on implementation CPUs
arm64: Make _midr_in_range_list() an exported function
KVM: arm64: Introduce KVM_REG_ARM_VENDOR_HYP_BMAP_2
KVM: arm64: Specify hypercall ABI for retrieving target implementations
arm64: Modify _midr_range() functions to read MIDR/REVIDR internally
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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* kvm-arm64/nv-idregs:
: Changes to exposure of NV features, courtesy of Marc Zyngier
:
: Apply NV-specific feature restrictions at reset rather than at the point
: of KVM_RUN. This makes the true feature set visible to userspace, a
: necessary step towards save/restore support or NV VMs.
:
: Add an additional vCPU feature flag for selecting the E2H0 flavor of NV,
: such that the VHE-ness of the VM can be applied to the feature set.
KVM: arm64: selftests: Test that TGRAN*_2 fields are writable
KVM: arm64: Allow userspace to write ID_AA64MMFR0_EL1.TGRAN*_2
KVM: arm64: Advertise FEAT_ECV when possible
KVM: arm64: Make ID_AA64MMFR4_EL1.NV_frac writable
KVM: arm64: Allow userspace to limit NV support to nVHE
KVM: arm64: Move NV-specific capping to idreg sanitisation
KVM: arm64: Enforce NV limits on a per-idregs basis
KVM: arm64: Make ID_REG_LIMIT_FIELD_ENUM() more widely available
KVM: arm64: Consolidate idreg callbacks
KVM: arm64: Advertise NV2 in the boot messages
KVM: arm64: Mark HCR.EL2.{NV*,AT} RES0 when ID_AA64MMFR4_EL1.NV_frac is 0
KVM: arm64: Mark HCR.EL2.E2H RES0 when ID_AA64MMFR1_EL1.VH is zero
KVM: arm64: Hide ID_AA64MMFR2_EL1.NV from guest and userspace
arm64: cpufeature: Handle NV_frac as a synonym of NV2
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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KVM selftests changes for 6.15, part 2
- Fix a variety of flaws, bugs, and false failures/passes dirty_log_test, and
improve its coverage by collecting all dirty entries on each iteration.
- Fix a few minor bugs related to handling of stats FDs.
- Add infrastructure to make vCPU and VM stats FDs available to tests by
default (open the FDs during VM/vCPU creation).
- Relax an assertion on the number of HLT exits in the xAPIC IPI test when
running on a CPU that supports AMD's Idle HLT (which elides interception of
HLT if a virtual IRQ is pending and unmasked).
- Misc cleanups and fixes.
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into HEAD
KVM selftests changes for 6.15, part 1
- Misc cleanups and prep work.
- Annotate _no_printf() with "printf" so that pr_debug() statements are
checked by the compiler for default builds (and pr_info() when QUIET).
- Attempt to whack the last LLC references/misses mole in the Intel PMU
counters test by adding a data load and doing CLFLUSH{OPT} on the data
instead of the code being executed. The theory is that modern Intel CPUs
have learned new code prefetching tricks that bypass the PMU counters.
- Fix a flaw in the Intel PMU counters test where it asserts that an event is
counting correctly without actually knowing what the event counts on the
underlying hardware.
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KVM x86 misc changes for 6.15:
- Fix a bug in PIC emulation that caused KVM to emit a spurious KVM_REQ_EVENT.
- Add a helper to consolidate handling of mp_state transitions, and use it to
clear pv_unhalted whenever a vCPU is made RUNNABLE.
- Defer runtime CPUID updates until KVM emulates a CPUID instruction, to
coalesce updates when multiple pieces of vCPU state are changing, e.g. as
part of a nested transition.
- Fix a variety of nested emulation bugs, and add VMX support for synthesizing
nested VM-Exit on interception (instead of injecting #UD into L2).
- Drop "support" for PV Async #PF with proctected guests without SEND_ALWAYS,
as KVM can't get the current CPL.
- Misc cleanups
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The KVM RISC-V allows Zaamo/Zalrsc extensions for Guest/VM so add these
extensions to get-reg-list test.
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240619153913.867263-6-cleger@rivosinc.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
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Userspace can write to these fields for non-NV guests; add test that do
just that.
Signed-off-by: Sebastian Ott <sebott@redhat.com>
Link: https://lore.kernel.org/kvmarm/20250306184013.30008-1-sebott@redhat.com/
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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It is helpful to vary the number of the LCOFI interrupts generated
by the overflow test. Allow additional argument for overflow test
to accommodate that. It can be easily cross-validated with
/proc/interrupts output in the host.
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250303-kvm_pmu_improve-v2-4-41d177e45929@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
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The PMU test commandline option takes an argument to disable a
certain test. The initial assumption behind this was a common use case
is just to run all the test most of the time. However, running a single
test seems more useful instead. Especially, the overflow test has been
helpful to validate PMU virtualizaiton interrupt changes.
Switching the command line option to run a single test instead
of disabling a single test also allows to provide additional
test specific arguments to the test. The default without any options
remains unchanged which continues to run all the tests.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20250303-kvm_pmu_improve-v2-3-41d177e45929@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
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There is no need to start the counter in the overflow handler as we
intend to trigger precise number of LCOFI interrupts through these
tests. The overflow irq handler has already stopped the counter. As
a result, the stop call from the test function may return already
stopped error which is fine as well.
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20250303-kvm_pmu_improve-v2-2-41d177e45929@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>
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Print out the index of mismatching XSAVE bytes using unsigned decimal
format. Some versions of clang complain about trying to print an integer
as an unsigned char.
x86/sev_smoke_test.c:55:51: error: format specifies type 'unsigned char'
but the argument has type 'int' [-Werror,-Wformat]
Fixes: 8c53183dbaa2 ("selftests: kvm: add test for transferring FPU state into VMSA")
Link: https://lore.kernel.org/r/20250228233852.3855676-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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During the initial mprotect(RO) stage of mmu_stress_test, keep vCPUs
spinning until all vCPUs have hit -EFAULT, i.e. until all vCPUs have tried
to write to a read-only page. If a vCPU manages to complete an entire
iteration of the loop without hitting a read-only page, *and* the vCPU
observes mprotect_ro_done before starting a second iteration, then the
vCPU will prematurely fall through to GUEST_SYNC(3) (on x86 and arm64) and
get out of sequence.
Replace the "do-while (!r)" loop around the associated _vcpu_run() with
a single invocation, as barring a KVM bug, the vCPU is guaranteed to hit
-EFAULT, and retrying on success is super confusion, hides KVM bugs, and
complicates this fix. The do-while loop was semi-unintentionally added
specifically to fudge around a KVM x86 bug, and said bug is unhittable
without modifying the test to force x86 down the !(x86||arm64) path.
On x86, if forced emulation is enabled, vcpu_arch_put_guest() may trigger
emulation of the store to memory. Due a (very, very) longstanding bug in
KVM x86's emulator, emulate writes to guest memory that fail during
__kvm_write_guest_page() unconditionally return KVM_EXIT_MMIO. While that
is desirable in the !memslot case, it's wrong in this case as the failure
happens due to __copy_to_user() hitting a read-only page, not an emulated
MMIO region.
But as above, x86 only uses vcpu_arch_put_guest() if the __x86_64__ guards
are clobbered to force x86 down the common path, and of course the
unexpected MMIO is a KVM bug, i.e. *should* cause a test failure.
Fixes: b6c304aec648 ("KVM: selftests: Verify KVM correctly handles mprotect(PROT_READ)")
Reported-by: Yan Zhao <yan.y.zhao@intel.com>
Closes: https://lore.kernel.org/all/20250208105318.16861-1-yan.y.zhao@intel.com
Debugged-by: Yan Zhao <yan.y.zhao@intel.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Tested-by: Yan Zhao <yan.y.zhao@intel.com>
Link: https://lore.kernel.org/r/20250228230804.3845860-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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If the CPU supports Idle HLT, which elides HLT VM-Exits if the vCPU has an
unmasked pending IRQ or NMI, relax the xAPIC IPI test's assertion on the
number of HLT exits to only require that the number of exits is less than
or equal to the number of HLT instructions that were executed. I.e. don't
fail the test if Idle HLT does what it's supposed to do.
Note, unfortunately there's no way to determine if *KVM* supports Idle HLT,
as this_cpu_has() checks raw CPU support, and kvm_cpu_has() checks what can
be exposed to L1, i.e. the latter would check if KVM supports nested Idle
HLT. But, since the assert is purely bonus coverage, checking for CPU
support is good enough.
Cc: Manali Shukla <Manali.Shukla@amd.com>
Tested-by: Manali Shukla <Manali.Shukla@amd.com>
Link: https://lore.kernel.org/r/20250226231809.3183093-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Add an L1 (guest) assert to the nested exceptions test to verify that KVM
doesn't put VMRUN in an STI shadow (AMD CPUs bleed the shadow into the
guest's int_state if a #VMEXIT occurs before VMRUN fully completes).
Add a similar assert to the VMX side as well, because why not.
Reviewed-by: Jim Mattson <jmattson@google.com>
Link: https://lore.kernel.org/r/20250224165442.2338294-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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There is a spelling mistake in a PER_PAGE_DEBUG debug message. Fix it.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20250227220819.656780-1-colin.i.king@gmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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One difference here with other pseudo-firmware bitmap registers
is that the default/reset value for the supported hypercall
function-ids is 0 at present. Hence, modify the test accordingly.
Reviewed-by: Sebastian Ott <sebott@redhat.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/r/20250221140229.12588-7-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Assert that MIDR_EL1, REVIDR_EL1, AIDR_EL1 are writable from userspace,
that the changed values are visible to guests, and that they are
preserved across a vCPU reset.
Signed-off-by: Sebastian Ott <sebott@redhat.com>
Link: https://lore.kernel.org/r/20250225005401.679536-6-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
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Add a rudimentary test for validating KVM's handling of L1 hypervisor
intercepts during instruction emulation on behalf of L2. To minimize
complexity and avoid overlap with other tests, only validate KVM's
handling of instructions that L1 wants to intercept, i.e. that generate a
nested VM-Exit. Full testing of emulation on behalf of L2 is better
achieved by running existing (forced) emulation tests in a VM, (although
on VMX, getting L0 to emulate on #UD requires modifying either L1 KVM to
not intercept #UD, or modifying L0 KVM to prioritize L0's exception
intercepts over L1's intercepts, as is done by KVM for SVM).
Since emulation should never be successful, i.e. L2 always exits to L1,
dynamically generate the L2 code stream instead of adding a helper for
each instruction. Doing so requires hand coding instruction opcodes, but
makes it significantly easier for the test to compute the expected "next
RIP" and instruction length.
Link: https://lore.kernel.org/r/20250201015518.689704-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Now that the binary stats cache infrastructure is largely scope agnostic,
add support for vCPU-scoped stats. Like VM stats, open and cache the
stats FD when the vCPU is created so that it's guaranteed to be valid when
vcpu_get_stats() is invoked.
Account for the extra per-vCPU file descriptor in kvm_set_files_rlimit(),
so that tests that create large VMs don't run afoul of resource limits.
To sanity check that the infrastructure actually works, and to get a bit
of bonus coverage, add an assert in x86's xapic_ipi_test to verify that
the number of HLTs executed by the test matches the number of HLT exits
observed by KVM.
Tested-by: Manali Shukla <Manali.Shukla@amd.com>
Link: https://lore.kernel.org/r/20250111005049.1247555-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Move the max vCPUs test's RLIMIT_NOFILE adjustments to common code, and
use the new helper to adjust the resource limit for non-barebones VMs by
default. x86's recalc_apic_map_test creates 512 vCPUs, and a future
change will open the binary stats fd for all vCPUs, which will put the
recalc APIC test above some distros' default limit of 1024.
Link: https://lore.kernel.org/r/20250111005049.1247555-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Get and cache a VM's binary stats FD when the VM is opened, as opposed to
waiting until the stats are first used. Opening the stats FD outside of
__vm_get_stat() will allow converting it to a scope-agnostic helper.
Note, this doesn't interfere with kvm_binary_stats_test's testcase that
verifies a stats FD can be used after its own VM's FD is closed, as the
cached FD is also closed during kvm_vm_free().
Link: https://lore.kernel.org/r/20250111005049.1247555-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Add a struct and helpers to manage the binary stats cache, which is
currently used only for VM-scoped stats. This will allow expanding the
selftests infrastructure to provide support for vCPU-scoped binary stats,
which, except for the ioctl to get the stats FD are identical to VM-scoped
stats.
Defer converting __vm_get_stat() to a scope-agnostic helper to a future
patch, as getting the stats FD from KVM needs to be moved elsewhere
before it can be made completely scope-agnostic.
Link: https://lore.kernel.org/r/20250111005049.1247555-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Turn vm_get_stat() into a macro that generates a string for the stat name,
as opposed to taking a string. This will allow hardening stat usage in
the future to generate errors on unknown stats at compile time.
No functional change intended.
Link: https://lore.kernel.org/r/20250111005049.1247555-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Fail the test if it attempts to read a stat that doesn't exist, e.g. due
to a typo (hooray, strings), or because the test tried to get a stat for
the wrong scope. As is, there's no indiciation of failure and @data is
left untouched, e.g. holds '0' or random stack data in most cases.
Fixes: 8448ec5993be ("KVM: selftests: Add NX huge pages test")
Link: https://lore.kernel.org/r/20250111005049.1247555-4-seanjc@google.com
[sean: fixup spelling mistake, courtesy of Colin Ian King]
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Close/free a VM's binary stats cache when the VM is released, not when the
VM is fully freed. When a VM is re-created, e.g. for state save/restore
tests, the stats FD and descriptor points at the old, defunct VM. The FD
is still valid, in that the underlying stats file won't be freed until the
FD is closed, but reading stats will always pull information from the old
VM.
Note, this is a benign bug in the current code base as none of the tests
that recreate VMs use binary stats.
Fixes: 83f6e109f562 ("KVM: selftests: Cache binary stats metadata for duration of test")
Link: https://lore.kernel.org/r/20250111005049.1247555-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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When allocating and freeing a VM's cached binary stats info, check for a
NULL descriptor, not a '0' file descriptor, as '0' is a legal FD. E.g. in
the unlikely scenario the kernel installs the stats FD at entry '0',
selftests would reallocate on the next __vm_get_stat() and/or fail to free
the stats in kvm_vm_free().
Fixes: 83f6e109f562 ("KVM: selftests: Cache binary stats metadata for duration of test")
Link: https://lore.kernel.org/r/20250111005049.1247555-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Now that dirty_log_test doesn't require running multiple iterations to
verify dirty pages, and actually runs the requested number of iterations,
drop the requirement that the test run at least "3" (which was really "2"
at the time the test was written) iterations.
Link: https://lore.kernel.org/r/20250111003004.1235645-21-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Actually run all requested iterations, instead of iterations-1 (the count
starts at '1' due to the need to avoid '0' as an in-memory value for a
dirty page).
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-20-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Set the per-iteration variables at the start of each iteration instead of
setting them before the loop, and at the end of each iteration. To ensure
the vCPU doesn't race ahead before the first iteration, simply have the
vCPU worker want for sem_vcpu_cont, which conveniently avoids the need to
special case posting sem_vcpu_cont from the loop.
Link: https://lore.kernel.org/r/20250111003004.1235645-19-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Now that each iteration collects all dirty entries and ensures the guest
*completes* at least one write, tighten the exemptions for the last dirty
page of the previous iteration. Specifically, the only legal value (other
than the current iteration) is N-1.
Unlike the last page for the current iteration, the in-progress write from
the previous iteration is guaranteed to have completed, otherwise the test
would have hung.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-18-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Ensure the vCPU fully completes at least one write in each dirty_log_test
iteration, as failure to dirty any pages complicates verification and
forces the test to be overly conservative about possible values. E.g.
verification needs to allow the last dirty page from a previous iteration
to have *any* value, because the vCPU could get stuck for multiple
iterations, which is unlikely but can happen in heavily overloaded and/or
nested virtualization setups.
Somewhat arbitrarily set the minimum to 0x100/256; high enough to be
interesting, but not so high as to lead to pointlessly long runtimes.
Opportunistically report the number of writes per iteration for debug
purposes, and so that a human can sanity check the test. Due to each
write targeting a random page, the number of dirty pages will likely be
lower than the number of total writes, but it shouldn't be absurdly lower
(which would suggest the pRNG is broken)
Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-17-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Add a sanity check that a completely garbage value wasn't written to
the last dirty page in the ring, e.g. that it doesn't contain the *next*
iteration's value.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-16-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Collect all dirty entries during each iteration of dirty_log_test by
doing a final collection after the vCPU has been stopped. To deal with
KVM's destructive approach to getting the dirty bitmaps, use a second
bitmap for the post-stop collection.
Collecting all entries that were dirtied during an iteration simplifies
the verification logic *and* improves test coverage.
- If a page is written during iteration X, but not seen as dirty until
X+1, the test can get a false pass if the page is also written during
X+1.
- If a dirty page used a stale value from a previous iteration, the test
would grant a false pass.
- If a missed dirty log occurs in the last iteration, the test would fail
to detect the issue.
E.g. modifying mark_page_dirty_in_slot() to dirty an unwritten gfn:
if (memslot && kvm_slot_dirty_track_enabled(memslot)) {
unsigned long rel_gfn = gfn - memslot->base_gfn;
u32 slot = (memslot->as_id << 16) | memslot->id;
if (!vcpu->extra_dirty &&
gfn_to_memslot(kvm, gfn + 1) == memslot) {
vcpu->extra_dirty = true;
mark_page_dirty_in_slot(kvm, memslot, gfn + 1);
}
if (kvm->dirty_ring_size && vcpu)
kvm_dirty_ring_push(vcpu, slot, rel_gfn);
else if (memslot->dirty_bitmap)
set_bit_le(rel_gfn, memslot->dirty_bitmap);
}
isn't detected with the current approach, even with an interval of 1ms
(when running nested in a VM; bare metal would be even *less* likely to
detect the bug due to the vCPU being able to dirty more memory). Whereas
collecting all dirty entries consistently detects failures with an
interval of 700ms or more (the longer interval means a higher probability
of an actual write to the prematurely-dirtied page).
Link: https://lore.kernel.org/r/20250111003004.1235645-15-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Print out the last dirty pages from the current and previous iteration on
verification failures. In many cases, bugs (especially test bugs) occur
on the edges, i.e. on or near the last pages, and being able to correlate
failures with the last pages can aid in debug.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-14-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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When verifying pages in dirty_log_test, immediately continue on all "pass"
scenarios to make the logic consistent in how it handles pass vs. fail.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-13-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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When running dirty_log_test using the dirty ring, post to sem_vcpu_stop
only when the main thread has explicitly requested that the vCPU stop.
Synchronizing the vCPU and main thread whenever the dirty ring happens to
be full is unnecessary, as KVM's ABI is to actively prevent the vCPU from
running until the ring is no longer full. I.e. attempting to run the vCPU
will simply result in KVM_EXIT_DIRTY_RING_FULL without ever entering the
guest. And if KVM doesn't exit, e.g. let's the vCPU dirty more pages,
then that's a KVM bug worth finding.
Posting to sem_vcpu_stop on ring full also makes it difficult to get the
test logic right, e.g. it's easy to let the vCPU keep running when it
shouldn't, as a ring full can essentially happen at any given time.
Opportunistically rework the handling of dirty_ring_vcpu_ring_full to
leave it set for the remainder of the iteration in order to simplify the
surrounding logic.
Link: https://lore.kernel.org/r/20250111003004.1235645-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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In the dirty_log_test guest code, exit to userspace only when the vCPU is
explicitly told to stop. Periodically exiting just to check if a flag has
been set is unnecessary, weirdly complex, and wastes time handling exits
that could be used to dirty memory.
Opportunistically convert 'i' to a uint64_t to guard against the unlikely
scenario that guest_num_pages exceeds the storage of an int.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Now that the vCPU doesn't dirty every page on the first iteration for
architectures that support the dirty ring, honor vcpu_stop in the dirty
ring's vCPU worker, i.e. stop when the main thread says "stop". This will
allow plumbing vcpu_stop into the guest so that the vCPU doesn't need to
periodically exit to userspace just to see if it should stop.
Add a comment explaining that marking all pages as dirty is problematic
for the dirty ring, as it results in the guest getting stuck on "ring
full". This could be addressed by adding a GUEST_SYNC() in that initial
loop, but it's not clear how that would interact with s390's behavior.
Link: https://lore.kernel.org/r/20250111003004.1235645-10-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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s390 specific workaround causes the dirty-log mode of the test to dirty
all guest memory on the first iteration, which is very slow when the test
is run in a nested VM.
Limit this workaround to s390x.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Continue collecting entries from the dirty ring for the entire time the
vCPU is running. Collecting exactly once all but guarantees the vCPU will
encounter a "ring full" event and stop. While testing ring full is
interesting, stopping and doing nothing is not, especially for larger
intervals as the test effectively does nothing for a much longer time.
To balance continuous collection with letting the guest make forward
progress, chunk the interval waiting into 1ms loops (which also makes
the math dead simple).
To maintain coverage for "ring full", collect entries on subsequent
iterations if and only if the ring has been filled at least once. I.e.
let the ring fill up (if the interval allows), but after that contiuously
empty it so that the vCPU can keep running.
Opportunistically drop unnecessary zero-initialization of "count".
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Cache the page's value during verification in a local variable, re-reading
from the pointer is ugly and error prone, e.g. allows for bugs like
checking the pointer itself instead of the value.
No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Track and print the number of dirty and clear pages for each iteration.
This provides parity between all log modes, and will allow collecting the
dirty ring multiple times per iteration without spamming the console.
Opportunistically drop the "Dirtied N pages" print, which is redundant
and wrong. For the dirty ring testcase, the vCPU isn't guaranteed to
complete a loop. And when the vCPU does complete a loot, there are no
guarantees that it has *dirtied* that many pages; because the writes are
to random address, the vCPU may have written the same page over and over,
i.e. only dirtied one page.
While the number of writes performed by the vCPU is also interesting,
e.g. the pr_info() could be tweaked to use different verbiage, pages_count
doesn't correctly track the number of writes either (because loops aren't
guaranteed to a complete). Delete the print for now, as a future patch
will precisely track the number of writes, at which point the verification
phase can report the number of writes performed by each iteration.
Link: https://lore.kernel.org/r/20250111003004.1235645-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Drop an srandom() initialization that was leftover from the conversion to
use selftests' guest_random_xxx() APIs.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Drop the signal/kick from dirty_log_test's dirty ring handling, as kicking
the vCPU adds marginal value, at the cost of adding significant complexity
to the test.
Asynchronously interrupting the vCPU isn't novel; unless the kernel is
fully tickless, the vCPU will be interrupted by IRQs for any decently
large interval.
And exiting to userspace mode in the middle of a sequence isn't novel
either, as the vCPU will do so every time the ring becomes full.
Link: https://lore.kernel.org/r/20250111003004.1235645-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Sync the new iteration to the guest prior to restarting the vCPU, otherwise
it's possible for the vCPU to dirty memory for the next iteration using the
current iteration's value.
Note, because the guest can be interrupted between the vCPU's load of the
iteration and its write to memory, it's still possible for the guest to
store the previous iteration to memory as the previous iteration may be
cached in a CPU register (which the test accounts for).
Note #2, the test's current approach of collecting dirty entries *before*
stopping the vCPU also results dirty memory having the previous iteration.
E.g. if page is dirtied in the previous iteration, but not the current
iteration, the verification phase will observe the previous iteration's
value in memory. That wart will be remedied in the near future, at which
point synchronizing the iteration before restarting the vCPU will guarantee
the only way for verification to observe stale iterations is due to the
CPU register caching case, or due to a dirty entry being collected before
the store retires.
Link: https://lore.kernel.org/r/20250111003004.1235645-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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If dirty_log_test is run nested, it is possible for entries in the emulated
PML log to appear before the actual memory write is committed to the RAM,
due to the way KVM retries memory writes as a response to a MMU fault.
In addition to that in some very rare cases retry can happen more than
once, which will lead to the test failure because once the write is
finally committed it may have a very outdated iteration value.
Detect and avoid this case.
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20250111003004.1235645-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Use KVM_ASM_SAFE_FEP, not simply KVM_ASM_SAFE, for kvm_asm_safe_fep(), as
the non-FEP version doesn't force emulation (stating the obvious). Note,
there are currently no users of kvm_asm_safe_fep().
Fixes: ab3b6a7de8df ("KVM: selftests: Add a forced emulation variation of KVM_ASM_SAFE()")
Link: https://lore.kernel.org/r/20250130163135.270770-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Add testcases to x86's Hyper-V CPUID test to verify that KVM advertises
support for features that require an in-kernel local APIC appropriately,
i.e. that KVM hides support from the vCPU-scoped ioctl if the VM doesn't
have an in-kernel local APIC.
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20250118003454.2619573-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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Allocate, get, and free the CPUID array in the Hyper-V CPUID test in the
test's core helper, instead of copy+pasting code at each call site. In
addition to deduplicating a small amount of code, restricting visibility
of the array to a single invocation of the core test prevents "leaking" an
array across test cases. Passing in @vcpu to the helper will also allow
pivoting on VM-scoped information without needing to pass more booleans,
e.g. to conditionally assert on features that require an in-kernel APIC.
To avoid use-after-free bugs due to overzealous and careless developers,
opportunstically add a comment to explain that the system-scoped helper
caches the Hyper-V CPUID entries, i.e. that the caller is not responsible
for freeing the memory.
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20250118003454.2619573-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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