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2025-06-05RISC-V: Documentation: Add enough title underlines to CMODXPalmer Dabbelt
This reports as a warning in linux-next along the lines of Documentation/arch/riscv/cmodx.rst:14: WARNING: Title underline too short. CMODX in the Kernel Space --------------------- [docutils] Documentation/arch/riscv/cmodx.rst:43: WARNING: Title underline too short. CMODX in the User Space --------------------- [docutils] Documentation/arch/riscv/cmodx.rst:43: WARNING: Title underline too short. CMODX in the User Space --------------------- [docutils] Link: https://lore.kernel.org/all/20250603154544.1602a8b5@canb.auug.org.au/ Fixes: 0e07200b2af6 ("riscv: Documentation: add a description about dynamic ftrace") Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20250603172856.49925-1-palmer@dabbelt.com Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
2025-06-05Merge tag 'riscv-mw1-6.16-rc1' of ↵Palmer Dabbelt
ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/alexghiti/linux into for-next riscv patches for 6.16-rc1 * Implement atomic patching support for ftrace which finally allows to get rid of stop_machine(). * Support for kexec_file_load() syscall * Improve module loading time by changing the algorithm that counts the number of plt/got entries in a module. * Zicbop is now used in the kernel to prefetch instructions [Palmer: There's been two rounds of surgery on this one, so as a result it's a bit different than the PR.] * alex-pr: (734 commits) riscv: Improve Kconfig help for RISCV_ISA_V_PREEMPTIVE MAINTAINERS: Update Atish's email address riscv: hwprobe: export Zabha extension riscv: Make regs_irqs_disabled() more clear perf symbols: Ignore mapping symbols on riscv RISC-V: Kconfig: Fix help text of CMDLINE_EXTEND riscv: module: Optimize PLT/GOT entry counting riscv: Add support for PUD THP riscv: xchg: Prefetch the destination word for sc.w riscv: Add ARCH_HAS_PREFETCH[W] support with Zicbop riscv: Add support for Zicbop riscv: Introduce Zicbop instructions riscv/kexec_file: Fix comment in purgatory relocator riscv: kexec_file: Support loading Image binary file riscv: kexec_file: Split the loading of kernel and others riscv: Documentation: add a description about dynamic ftrace riscv: ftrace: support direct call using call_ops riscv: Implement HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS riscv: ftrace: support PREEMPT riscv: add a data fence for CMODX in the kernel mode ... Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
2025-06-05riscv: hwprobe: export Zabha extensionAlexandre Ghiti
Export Zabha through the hwprobe syscall. Reviewed-by: Clément Léger <cleger@rivosinc.com> Link: https://lore.kernel.org/r/20250421141413.394444-1-alexghiti@rivosinc.com Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
2025-06-05riscv: Documentation: add a description about dynamic ftraceAndy Chiu
Add a section in cmodx to describe how dynamic ftrace works on riscv, limitations, and assumptions. Signed-off-by: Andy Chiu <andybnac@gmail.com> Link: https://lore.kernel.org/r/20250407180838.42877-12-andybnac@gmail.com Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
2025-05-08riscv: hwprobe: Document SiFive xsfvfwmaccqqq vendor extensionCyan Yang
Document the support for matrix multiply accumulate instruction from SiFive using RISCV_HWPROBE_VENDOR_EXT_XSFVFWMACCQQQ. Signed-off-by: Cyan Yang <cyan.yang@sifive.com> Link: https://lore.kernel.org/r/20250418053239.4351-12-cyan.yang@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2025-05-08riscv: hwprobe: Document SiFive xsfvfnrclipxfqf vendor extensionCyan Yang
Document the support for SiFive vendor extensions for FP32-to-int8 Ranged Clip Instructions using RISCV_HWPROBE_VENDOR_EXT_XSFVFNRCLIPXFQF. Signed-off-by: Cyan Yang <cyan.yang@sifive.com> Link: https://lore.kernel.org/r/20250418053239.4351-8-cyan.yang@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2025-05-08riscv: hwprobe: Document SiFive xsfvqmaccdod and xsfvqmaccqoq vendor extensionsCyan Yang
Document the support for sifive vendor extensions using the key RISCV_HWPROBE_KEY_VENDOR_EXT_SIFIVE_0 and two vendor extensions for SiFive Int8 Matrix Multiplication Instructions using RISCV_HWPROBE_VENDOR_EXT_XSFVQMACCDOD and RISCV_HWPROBE_VENDOR_EXT_XSFVQMACCQOQ. Signed-off-by: Cyan Yang <cyan.yang@sifive.com> Link: https://lore.kernel.org/r/20250418053239.4351-4-cyan.yang@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2025-04-07Documentation: riscv: Fix typo MIMPLID -> MIMPIDNam Cao
The macro that is really defined is RISCV_HWPROBE_KEY_MIMPID, not RISCV_HWPROBE_KEY_MIMPLID (difference is the 'L'). Also, the riscv privileged specification names the register "mimpid", not "mimplid". Correct these typos. Signed-off-by: Nam Cao <namcao@linutronix.de> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Evan Green <evan@rivosinc.com> Link: https://lore.kernel.org/r/20240925142532.31808-1-namcao@linutronix.de Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
2025-03-19riscv: hwprobe: export Zaamo and Zalrsc extensionsClément Léger
Export the Zaamo and Zalrsc extensions to userspace using hwprobe. Signed-off-by: Clément Léger <cleger@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20240619153913.867263-4-cleger@rivosinc.com Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
2025-03-18RISC-V: hwprobe: Expose Zicbom extension and its block sizeYunhui Cui
Expose Zicbom through hwprobe and also provide a key to extract its respective block size. [ alex: Fix merge conflicts and hwprobe numbering ] Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Samuel Holland <samuel.holland@sifive.com> Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com> Link: https://lore.kernel.org/r/20250226063206.71216-3-cuiyunhui@bytedance.com Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
2025-03-18Merge patch series "riscv: Add bfloat16 instruction support"Alexandre Ghiti
Inochi Amaoto <inochiama@gmail.com> says: Add description for the BFloat16 precision Floating-Point ISA extension, (Zfbfmin, Zvfbfmin, Zvfbfwma). which was ratified in commit 4dc23d62 ("Added Chapter title to BF16") of the riscv-isa-manual. * patches from https://lore.kernel.org/r/20250213003849.147358-1-inochiama@gmail.com: riscv: hwprobe: export bfloat16 ISA extension riscv: add ISA extension parsing for bfloat16 ISA extension dt-bindings: riscv: add bfloat16 ISA extension description Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20250213003849.147358-1-inochiama@gmail.com
2025-03-18riscv: hwprobe: export bfloat16 ISA extensionInochi Amaoto
Export Zfbmin, Zvfbfmin, Zvfbfwma ISA extension through hwprobe. Signed-off-by: Inochi Amaoto <inochiama@gmail.com> Reviewed-by: Clément Léger <cleger@rivosinc.com> Link: https://lore.kernel.org/r/20250213003849.147358-4-inochiama@gmail.com Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
2025-03-18riscv: hwprobe: export Zicntr and Zihpm extensionsMiquel Sabaté Solà
Export Zicntr and Zihpm ISA extensions through the hwprobe syscall. [ alex: Fix hwprobe numbering ] Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com> Acked-by: Jesse Taube <jesse@rivosinc.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20240913051324.8176-1-mikisabate@gmail.com Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
2025-01-18riscv: hwprobe: Document thead vendor extensions and xtheadvector extensionCharlie Jenkins
Document support for thead vendor extensions using the key RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 and xtheadvector extension using the key RISCV_HWPROBE_VENDOR_EXT_XTHEADVECTOR. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> Reviewed-by: Evan Green <evan@rivosinc.com> Tested-by: Yangyu Chen <cyy@cyyself.name> Link: https://lore.kernel.org/r/20241113-xtheadvector-v11-11-236c22791ef9@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-10-24Merge patch series "riscv: Userspace pointer masking and tagged address ABI"Palmer Dabbelt
Samuel Holland <samuel.holland@sifive.com> says: RISC-V defines three extensions for pointer masking[1]: - Smmpm: configured in M-mode, affects M-mode - Smnpm: configured in M-mode, affects the next lower mode (S or U-mode) - Ssnpm: configured in S-mode, affects the next lower mode (VS, VU, or U-mode) This series adds support for configuring Smnpm or Ssnpm (depending on which privilege mode the kernel is running in) to allow pointer masking in userspace (VU or U-mode), extending the PR_SET_TAGGED_ADDR_CTRL API from arm64. Unlike arm64 TBI, userspace pointer masking is not enabled by default on RISC-V. Additionally, the tag width (referred to as PMLEN) is variable, so userspace needs to ask the kernel for a specific tag width, which is interpreted as a lower bound on the number of tag bits. This series also adds support for a tagged address ABI similar to arm64 and x86. Since accesses from the kernel to user memory use the kernel's pointer masking configuration, not the user's, the kernel must untag user pointers in software before dereferencing them. And since the tag width is variable, as with LAM on x86, it must be kept the same across all threads in a process so untagged_addr_remote() can work. [1]: https://github.com/riscv/riscv-j-extension/raw/d70011dde6c2/zjpm-spec.pdf * b4-shazam-merge: KVM: riscv: selftests: Add Smnpm and Ssnpm to get-reg-list test RISC-V: KVM: Allow Smnpm and Ssnpm extensions for guests riscv: hwprobe: Export the Supm ISA extension riscv: selftests: Add a pointer masking test riscv: Allow ptrace control of the tagged address ABI riscv: Add support for the tagged address ABI riscv: Add support for userspace pointer masking riscv: Add CSR definitions for pointer masking riscv: Add ISA extension parsing for pointer masking dt-bindings: riscv: Add pointer masking ISA extensions Link: https://lore.kernel.org/r/20241016202814.4061541-1-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-10-24riscv: hwprobe: Export the Supm ISA extensionSamuel Holland
Supm is a virtual ISA extension defined in the RISC-V Pointer Masking specification, which indicates that pointer masking is available in U-mode. It can be provided by either Smnpm or Ssnpm, depending on which mode the kernel runs in. Userspace should not care about this distinction, so export Supm instead of either underlying extension. Hide the extension if the kernel was compiled without support for the pointer masking prctl() interface. Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20241016202814.4061541-9-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-10-24riscv: Add support for the tagged address ABISamuel Holland
When pointer masking is enabled for userspace, the kernel can accept tagged pointers as arguments to some system calls. Allow this by untagging the pointers in access_ok() and the uaccess routines. The uaccess routines must peform untagging in software because U-mode and S-mode have entirely separate pointer masking configurations. In fact, hardware may not even implement pointer masking for S-mode. Since the number of tag bits is variable, untagged_addr_remote() needs to know what PMLEN to use for the remote mm. Therefore, the pointer masking mode must be the same for all threads sharing an mm. Enforce this with a lock flag in the mm context, as x86 does for LAM. The flag gets reset in init_new_context() during fork(), as the new mm is no longer multithreaded. Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Tested-by: Charlie Jenkins <charlie@rivosinc.com> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20241016202814.4061541-6-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-10-24riscv: Add support for userspace pointer maskingSamuel Holland
RISC-V supports pointer masking with a variable number of tag bits (which is called "PMLEN" in the specification) and which is configured at the next higher privilege level. Wire up the PR_SET_TAGGED_ADDR_CTRL and PR_GET_TAGGED_ADDR_CTRL prctls so userspace can request a lower bound on the number of tag bits and determine the actual number of tag bits. As with arm64's PR_TAGGED_ADDR_ENABLE, the pointer masking configuration is thread-scoped, inherited on clone() and fork() and cleared on execve(). Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Tested-by: Charlie Jenkins <charlie@rivosinc.com> Signed-off-by: Samuel Holland <samuel.holland@sifive.com> Link: https://lore.kernel.org/r/20241016202814.4061541-5-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-10-18RISC-V: hwprobe: Document unaligned vector perf keyJesse Taube
Document key for reporting the speed of unaligned vector accesses. The descriptions are the same as the scalar equivalent values. Signed-off-by: Jesse Taube <jesse@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20241017-jesse_unaligned_vector-v10-6-5b33500160f8@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-09-17Merge tag 'docs-6.12' of git://git.lwn.net/linuxLinus Torvalds
Pull documentation update from Jonathan Corbet: "Another relatively mundane cycle for docs: - The beginning of an EEVDF scheduler document - More Chinese translations - A rethrashing of our bisection documentation ...plus the usual array of smaller fixes, and more than the usual number of typo fixes" * tag 'docs-6.12' of git://git.lwn.net/linux: (48 commits) Remove duplicate "and" in 'Linux NVMe docs. docs:filesystems: fix spelling and grammar mistakes docs:filesystem: fix mispelled words on autofs page docs:mm: fixed spelling and grammar mistakes on vmalloc kernel stack page Documentation: PCI: fix typo in pci.rst docs/zh_CN: add the translation of kbuild/gcc-plugins.rst docs/process: fix typos docs:mm: fix spelling mistakes in heterogeneous memory management page accel/qaic: Fix a typo docs/zh_CN: update the translation of security-bugs docs: block: Fix grammar and spelling mistakes in bfq-iosched.rst Documentation: Fix spelling mistakes Documentation/gpu: Fix typo in Documentation/gpu/komeda-kms.rst scripts: sphinx-pre-install: remove unnecessary double check for $cur_version Loongarch: KVM: Add KVM hypercalls documentation for LoongArch Documentation: Document the kernel flag bdev_allow_write_mounted docs: scheduler: completion: Update member of struct completion docs: kerneldoc-preamble.sty: Suppress extra spaces in CJK literal blocks docs: submitting-patches: Advertise b4 docs: update dev-tools/kcsan.rst url about KTSAN ...
2024-09-05Documentation: Fix spelling mistakesAmit Vadhavana
Correct spelling mistakes in the documentation to improve readability. Signed-off-by: Amit Vadhavana <av2082000@gmail.com> Reviewed-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20240817072724.6861-1-av2082000@gmail.com
2024-08-29Merge patch series "riscv: mm: Do not restrict mmap address based on hint"Palmer Dabbelt
Charlie Jenkins <charlie@rivosinc.com> says: There have been a couple of reports that using the hint address to restrict the address returned by mmap hint address has caused issues in applications. A different solution for restricting addresses returned by mmap is necessary to avoid breakages. [Palmer: This also just wasn't doing the right thing in the first place, as it didn't handle the sv39 cases we were trying to deal with.] * b4-shazam-merge: riscv: mm: Do not restrict mmap address based on hint riscv: selftests: Remove mmap hint address checks Revert "RISC-V: mm: Document mmap changes" Link: https://lore.kernel.org/r/20240826-riscv_mmap-v1-0-cd8962afe47f@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-08-29Revert "RISC-V: mm: Document mmap changes"Charlie Jenkins
This mmap behavior caused unintended breakages so the behavior has been changed. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20240826-riscv_mmap-v1-1-cd8962afe47f@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-08-14RISC-V: hwprobe: Add SCALAR to misaligned perf definesEvan Green
In preparation for misaligned vector performance hwprobe keys, rename the hwprobe key values associated with misaligned scalar accesses to include the term SCALAR. Leave the old defines in place to maintain source compatibility. This change is intended to be a functional no-op. Signed-off-by: Evan Green <evan@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20240809214444.3257596-3-evan@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-08-14RISC-V: hwprobe: Add MISALIGNED_PERF keyEvan Green
RISCV_HWPROBE_KEY_CPUPERF_0 was mistakenly flagged as a bitmask in hwprobe_key_is_bitmask(), when in reality it was an enum value. This causes problems when used in conjunction with RISCV_HWPROBE_WHICH_CPUS, since SLOW, FAST, and EMULATED have values whose bits overlap with each other. If the caller asked for the set of CPUs that was SLOW or EMULATED, the returned set would also include CPUs that were FAST. Introduce a new hwprobe key, RISCV_HWPROBE_KEY_MISALIGNED_PERF, which returns the same values in response to a direct query (with no flags), but is properly handled as an enumerated value. As a result, SLOW, FAST, and EMULATED are all correctly treated as distinct values under the new key when queried with the WHICH_CPUS flag. Leave the old key in place to avoid disturbing applications which may have already come to rely on the key, with or without its broken behavior with respect to the WHICH_CPUS flag. Fixes: e178bf146e4b ("RISC-V: hwprobe: Introduce which-cpus flag") Signed-off-by: Evan Green <evan@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Link: https://lore.kernel.org/r/20240809214444.3257596-2-evan@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-07-26RISC-V: Provide the frequency of time CSR via hwprobePalmer Dabbelt
The RISC-V architecture makes a real time counter CSR (via RDTIME instruction) available for applications in U-mode but there is no architected mechanism for an application to discover the frequency the counter is running at. Some applications (e.g., DPDK) use the time counter for basic performance analysis as well as fine grained time-keeping. Add support to the hwprobe system call to export the time CSR frequency to code running in U-mode. Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com> Reviewed-by: Evan Green <evan@rivosinc.com> Reviewed-by: Anup Patel <anup@brainfault.org> Acked-by: Punit Agrawal <punit.agrawal@bytedance.com> Link: https://lore.kernel.org/r/20240702033731.71955-2-cuiyunhui@bytedance.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-07-26riscv: Extend sv39 linear mapping max size to 128GStuart Menefy
This harmonizes all virtual addressing modes which can now all map (PGDIR_SIZE * PTRS_PER_PGD) / 4 of physical memory. The RISCV implementation of KASAN requires that the boundary between shallow mappings are aligned on an 8G boundary. In this case we need VMALLOC_START to be 8G aligned. So although we only need to move the start of the linear mapping down by 4GiB to allow 128GiB to be mapped, we actually move it down by 8GiB (creating a 4GiB hole between the linear mapping and KASAN shadow space) to maintain the alignment requirement. Signed-off-by: Stuart Menefy <stuart.menefy@codasip.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240630110550.1731929-1-stuart.menefy@codasip.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-07-20Merge tag 'riscv-for-linus-6.11-mw1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux Pull RISC-V updates from Palmer Dabbelt: - Support for various new ISA extensions: * The Zve32[xf] and Zve64[xfd] sub-extensios of the vector extension * Zimop and Zcmop for may-be-operations * The Zca, Zcf, Zcd and Zcb sub-extensions of the C extension * Zawrs - riscv,cpu-intc is now dtschema - A handful of performance improvements and cleanups to text patching - Support for memory hot{,un}plug - The highest user-allocatable virtual address is now visible in hwprobe * tag 'riscv-for-linus-6.11-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (58 commits) riscv: lib: relax assembly constraints in hweight riscv: set trap vector earlier KVM: riscv: selftests: Add Zawrs extension to get-reg-list test KVM: riscv: Support guest wrs.nto riscv: hwprobe: export Zawrs ISA extension riscv: Add Zawrs support for spinlocks dt-bindings: riscv: Add Zawrs ISA extension description riscv: Provide a definition for 'pause' riscv: hwprobe: export highest virtual userspace address riscv: Improve sbi_ecall() code generation by reordering arguments riscv: Add tracepoints for SBI calls and returns riscv: Optimize crc32 with Zbc extension riscv: Enable DAX VMEMMAP optimization riscv: mm: Add support for ZONE_DEVICE virtio-mem: Enable virtio-mem for RISC-V riscv: Enable memory hotplugging for RISC-V riscv: mm: Take memory hotplug read-lock during kernel page table dump riscv: mm: Add memory hotplugging support riscv: mm: Add pfn_to_kaddr() implementation riscv: mm: Refactor create_linear_mapping_range() for memory hot add ...
2024-07-12Merge patch series "riscv: Apply Zawrs when available"Palmer Dabbelt
Andrew Jones <ajones@ventanamicro.com> says: Zawrs provides two instructions (wrs.nto and wrs.sto), where both are meant to allow the hart to enter a low-power state while waiting on a store to a memory location. The instructions also both wait an implementation-defined "short" duration (unless the implementation terminates the stall for another reason). The difference is that while wrs.sto will terminate when the duration elapses, wrs.nto, depending on configuration, will either just keep waiting or an ILL exception will be raised. Linux will use wrs.nto, so if platforms have an implementation which falls in the "just keep waiting" category (which is not expected), then it should _not_ advertise Zawrs in the hardware description. Like wfi (and with the same {m,h}status bits to configure it), when wrs.nto is configured to raise exceptions it's expected that the higher privilege level will see the instruction was a wait instruction, do something, and then resume execution following the instruction. For example, KVM does configure exceptions for wfi (hstatus.VTW=1) and therefore also for wrs.nto. KVM does this for wfi since it's better to allow other tasks to be scheduled while a VCPU waits for an interrupt. For waits such as those where wrs.nto/sto would be used, which are typically locks, it is also a good idea for KVM to be involved, as it can attempt to schedule the lock holding VCPU. This series starts with Christoph's addition of the riscv smp_cond_load_relaxed function which applies wrs.sto when available. That patch has been reworked to use wrs.nto and to use the same approach as Arm for the wait loop, since we can't have arbitrary C code between the load-reserved and the wrs. Then, hwprobe support is added (since the instructions are also usable from usermode), and finally KVM is taught about wrs.nto, allowing guests to see and use the Zawrs extension. We still don't have test results from hardware, and it's not possible to prove that using Zawrs is a win when testing on QEMU, not even when oversubscribing VCPUs to guests. However, it is possible to use KVM selftests to force a scenario where we can prove Zawrs does its job and does it well. [4] is a test which does this and, on my machine, without Zawrs it takes 16 seconds to complete and with Zawrs it takes 0.25 seconds. This series is also available here [1]. In order to use QEMU for testing a build with [2] is needed. In order to enable guests to use Zawrs with KVM using kvmtool, the branch at [3] may be used. [1] https://github.com/jones-drew/linux/commits/riscv/zawrs-v3/ [2] https://lore.kernel.org/all/20240312152901.512001-2-ajones@ventanamicro.com/ [3] https://github.com/jones-drew/kvmtool/commits/riscv/zawrs/ [4] https://github.com/jones-drew/linux/commit/cb2beccebcece10881db842ed69bdd5715cfab5d Link: https://lore.kernel.org/r/20240426100820.14762-8-ajones@ventanamicro.com * b4-shazam-merge: KVM: riscv: selftests: Add Zawrs extension to get-reg-list test KVM: riscv: Support guest wrs.nto riscv: hwprobe: export Zawrs ISA extension riscv: Add Zawrs support for spinlocks dt-bindings: riscv: Add Zawrs ISA extension description riscv: Provide a definition for 'pause' Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-07-12riscv: hwprobe: export Zawrs ISA extensionAndrew Jones
Export Zawrs ISA extension through hwprobe. [Palmer: there's a gap in the numbers here as there will be a merge conflict when this is picked up. To avoid confusion I just set the hwprobe ID to match what it would be post-merge.] Signed-off-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Clément Léger <cleger@rivosinc.com> Link: https://lore.kernel.org/r/20240426100820.14762-12-ajones@ventanamicro.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-07-11riscv: hwprobe: export highest virtual userspace addressClément Léger
Some userspace applications (OpenJDK for instance) uses the free MSBs in pointers to insert additional information for their own logic and need to get this information from somewhere. Currently they rely on parsing /proc/cpuinfo "mmu=svxx" string to obtain the current value of virtual address usable bits [1]. Since this reflect the raw supported MMU mode, it might differ from the logical one used internally which is why arch_get_mmap_end() is used. Exporting the highest mmapable address through hwprobe will allow a more stable interface to be used. For that purpose, add a new hwprobe key named RISCV_HWPROBE_KEY_HIGHEST_VIRT_ADDRESS which will export the highest userspace virtual address. Link: https://github.com/openjdk/jdk/blob/master/src/hotspot/os_cpu/linux_riscv/vm_version_linux_riscv.cpp#L171 [1] Signed-off-by: Clément Léger <cleger@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20240410144558.1104006-1-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-07-01documentation: Fix riscv cmodx exampleCharlie Jenkins
ON/OFF in the keys was swapped between the first and second argument of the prctl. The prctl key is always PR_RISCV_SET_ICACHE_FLUSH_CTX, and the second argument can be PR_RISCV_CTX_SW_FENCEI_ON or PR_RISCV_CTX_SW_FENCEI_OFF. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> Fixes: 6a08e4709c58 ("documentation: Document PR_RISCV_SET_ICACHE_FLUSH_CTX prctl") Link: https://lore.kernel.org/r/20240628-fix_cmodx_example-v1-1-e6c6523bc163@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-06-26riscv: hwprobe: export Zcmop ISA extensionClément Léger
Export Zcmop ISA extension through hwprobe. Signed-off-by: Clément Léger <cleger@rivosinc.com> Reviewed-by: Evan Green <evan@rivosinc.com> Link: https://lore.kernel.org/r/20240619113529.676940-15-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-06-26riscv: hwprobe: export Zca, Zcf, Zcd and Zcb ISA extensionsClément Léger
Export Zca, Zcf, Zcd and Zcb ISA extension through hwprobe. Signed-off-by: Clément Léger <cleger@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20240619113529.676940-10-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-06-26riscv: hwprobe: export Zimop ISA extensionClément Léger
Export Zimop ISA extension through hwprobe. Signed-off-by: Clément Léger <cleger@rivosinc.com> Reviewed-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20240619113529.676940-4-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-05-30riscv: hwprobe: add zve Vector subextensions into hwprobe interfaceAndy Chiu
The following Vector subextensions for "embedded" platforms are added into RISCV_HWPROBE_KEY_IMA_EXT_0: - ZVE32X - ZVE32F - ZVE64X - ZVE64F - ZVE64D Extensions ending with an X indicates that the platform doesn't have a vector FPU. Extensions ending with F/D mean that whether single (F) or double (D) precision vector operation is supported. The number 32 or 64 follows from ZVE tells the maximum element length. Signed-off-by: Andy Chiu <andy.chiu@sifive.com> Reviewed-by: Clément Léger <cleger@rivosinc.com> Link: https://lore.kernel.org/r/20240510-zve-detection-v5-6-0711bdd26c12@sifive.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-05-30Documentation: RISC-V: uabi: Only scalar misaligned loads are supportedPalmer Dabbelt
We're stuck supporting scalar misaligned loads in userspace because they were part of the ISA at the time we froze the uABI. That wasn't the case for vector misaligned accesses, so depending on them unconditionally is a userspace bug. All extant vector hardware traps on these misaligned accesses. Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Link: https://lore.kernel.org/r/20240524185600.5919-1-palmer@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-04-30Merge patch series "riscv: Create and document PR_RISCV_SET_ICACHE_FLUSH_CTX ↵Palmer Dabbelt
prctl" Charlie Jenkins <charlie@rivosinc.com> says: Improve the performance of icache flushing by creating a new prctl flag PR_RISCV_SET_ICACHE_FLUSH_CTX. The interface is left generic to allow for future expansions such as with the proposed J extension [1]. Documentation is also provided to explain the use case. Patch sent to add PR_RISCV_SET_ICACHE_FLUSH_CTX to man-pages [2]. [1] https://github.com/riscv/riscv-j-extension [2] https://lore.kernel.org/linux-man/20240124-fencei_prctl-v1-1-0bddafcef331@rivosinc.com * b4-shazam-merge: cpumask: Add assign cpu documentation: Document PR_RISCV_SET_ICACHE_FLUSH_CTX prctl riscv: Include riscv_set_icache_flush_ctx prctl riscv: Remove unnecessary irqflags processor.h include Link: https://lore.kernel.org/r/20240312-fencei-v13-0-4b6bdc2bbf32@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-04-28riscv: hwprobe: export Zihintpause ISA extensionClément Léger
Export the Zihintpause ISA extension through hwprobe which allows using "pause" instructions. Some userspace applications (OpenJDK for instance) uses this to handle some locking back-off. Signed-off-by: Clément Léger <cleger@rivosinc.com> Reviewed-by: Atish Patra <atishp@rivosinc.com> Link: https://lore.kernel.org/r/20240221083108.1235311-1-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-04-18documentation: Document PR_RISCV_SET_ICACHE_FLUSH_CTX prctlCharlie Jenkins
Provide documentation that explains how to properly do CMODX in riscv. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> Reviewed-by: Atish Patra <atishp@rivosinc.com> Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com> Link: https://lore.kernel.org/r/20240312-fencei-v13-3-4b6bdc2bbf32@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-03-14docs: riscv: Define behavior of mmapCharlie Jenkins
Define mmap on riscv to not provide an address that uses more bits than the hint address, if provided. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> Link: https://lore.kernel.org/r/20240130-use_mmap_hint_address-v3-3-8a655cfa8bcb@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-17Merge tag 'docs-6.8-2' of git://git.lwn.net/linuxLinus Torvalds
Pull documentation fixes from Jonathan Corbet: "A handful of late-arriving documentation fixes" * tag 'docs-6.8-2' of git://git.lwn.net/linux: docs, kprobes: Add loongarch as supported architecture docs, kprobes: Update email address of Masami Hiramatsu docs: admin-guide: hw_random: update rng-tools website Documentation/core-api: fix spelling mistake in workqueue docs: kernel_feat.py: fix potential command injection Documentation: constrain alabaster package to older versions
2024-01-11docs: kernel_feat.py: fix potential command injectionVegard Nossum
The kernel-feat directive passes its argument straight to the shell. This is unfortunate and unnecessary. Let's always use paths relative to $srctree/Documentation/ and use subprocess.check_call() instead of subprocess.Popen(shell=True). This also makes the code shorter. This is analogous to commit 3231dd586277 ("docs: kernel_abi.py: fix command injection") where we did exactly the same thing for kernel_abi.py, somehow I completely missed this one. Link: https://fosstodon.org/@jani/111676532203641247 Reported-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Cc: stable@vger.kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20240110174758.3680506-1-vegard.nossum@oracle.com
2024-01-09Merge patch series "riscv: hwprobe: add Zicond, Zacas and Ztso support"Palmer Dabbelt
Clément Léger <cleger@rivosinc.com> says: This series add support for a few more extensions that are present in the RVA22U64/RVA23U64 (either mandatory or optional) and that are useful for userspace: - Zicond - Zacas - Ztso Series currently based on riscv/for-next. * b4-shazam-lts: riscv: hwprobe: export Zicond extension riscv: hwprobe: export Zacas ISA extension riscv: add ISA extension parsing for Zacas dt-bindings: riscv: add Zacas ISA extension description riscv: hwprobe: export Ztso ISA extension riscv: add ISA extension parsing for Ztso Link: https://lore.kernel.org/r/20231220155723.684081-1-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-09riscv: hwprobe: export Zicond extensionClément Léger
Export the zicond extension to userspace using hwprobe. Signed-off-by: Clément Léger <cleger@rivosinc.com> Link: https://lore.kernel.org/r/20231220155723.684081-7-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-09riscv: hwprobe: export Zacas ISA extensionClément Léger
Export Zacas ISA extension through hwprobe. Signed-off-by: Clément Léger <cleger@rivosinc.com> Link: https://lore.kernel.org/r/20231220155723.684081-6-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-09riscv: hwprobe: export Ztso ISA extensionClément Léger
Export the Ztso extension to userspace. Signed-off-by: Clément Léger <cleger@rivosinc.com> Link: https://lore.kernel.org/r/20231220155723.684081-3-cleger@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-09Merge patch series "RISC-V: hwprobe: Introduce which-cpus"Palmer Dabbelt
Andrew Jones <ajones@ventanamicro.com> says: This series introduces a flag for the hwprobe syscall which effectively reverses its behavior from getting the values of keys for a set of cpus to getting the cpus for a set of key-value pairs. * b4-shazam-merge: RISC-V: selftests: Add which-cpus hwprobe test RISC-V: hwprobe: Introduce which-cpus flag RISC-V: Move the hwprobe syscall to its own file RISC-V: hwprobe: Clarify cpus size parameter Link: https://lore.kernel.org/r/20231122164700.127954-6-ajones@ventanamicro.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-03RISC-V: hwprobe: Introduce which-cpus flagAndrew Jones
Introduce the first flag for the hwprobe syscall. The flag basically reverses its behavior, i.e. instead of populating the values of keys for a given set of cpus, the set of cpus after the call is the result of finding a set which supports the values of the keys. In order to do this, we implement a pair compare function which takes the type of value (a single value vs. a bitmask of booleans) into consideration. We also implement vdso support for the new flag. Signed-off-by: Andrew Jones <ajones@ventanamicro.com> Reviewed-by: Evan Green <evan@rivosinc.com> Link: https://lore.kernel.org/r/20231122164700.127954-9-ajones@ventanamicro.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2024-01-03RISC-V: hwprobe: Clarify cpus size parameterAndrew Jones
The "count" parameter associated with the 'cpus' parameter of the hwprobe syscall is the size in bytes of 'cpus'. Naming it 'cpu_count' may mislead users (it did me) to think it's the number of CPUs that are or can be represented by 'cpus' instead. This is particularly easy (IMO) to get wrong since 'cpus' is documented to be defined by CPU_SET(3) and CPU_SET(3) also documents a CPU_COUNT() (the number of CPUs in set) macro. CPU_SET(3) refers to the size of cpu sets with 'setsize'. Adopt 'cpusetsize' for the hwprobe parameter and specifically state it is in bytes in Documentation/riscv/hwprobe.rst to clarify. Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com> Reviewed-by: Conor Dooley <conor.dooley@microchip.com> Signed-off-by: Andrew Jones <ajones@ventanamicro.com> Link: https://lore.kernel.org/r/20231122164700.127954-7-ajones@ventanamicro.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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