| Message ID | 20230317113538.10878-1-andy.chiu@sifive.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | riscv: Add vector ISA support | expand |
Andy Chiu <andy.chiu@sifive.com> writes: > This patchset is implemented based on vector 1.0 spec to add vector support > in riscv Linux kernel. There are some assumptions for this implementations. > > 1. We assume all harts has the same ISA in the system. > 2. We disable vector in both kernel andy user space [1] by default. Only > enable an user's vector after an illegal instruction trap where it > actually starts executing vector (the first-use trap [2]). > 3. We detect "riscv,isa" to determine whether vector is support or not. > > We defined a new structure __riscv_v_ext_state in struct thread_struct to > save/restore the vector related registers. It is used for both kernel space > and user space. > - In kernel space, the datap pointer in __riscv_v_ext_state will be > allocated to save vector registers. > - In user space, > - In signal handler of user space, the structure is placed > right after __riscv_ctx_hdr, which is embedded in fp reserved > aera. This is required to avoid ABI break [2]. And datap points > to the end of __riscv_v_ext_state. > - In ptrace, the data will be put in ubuf in which we use > riscv_vr_get()/riscv_vr_set() to get or set the > __riscv_v_ext_state data structure from/to it, datap pointer > would be zeroed and vector registers will be copied to the > address right after the __riscv_v_ext_state structure in ubuf. > > This patchset is rebased to v6.3-rc1 and it is tested by running several > vector programs simultaneously. It delivers signals correctly in a test > where we can see a valid ucontext_t in a signal handler, and a correct V > context returing back from it. And the ptrace interface is tested by > PTRACE_{GET,SET}REGSET. Lastly, KVM is tested by running above tests in > a guest using the same kernel image. All tests are done on an rv64gcv > virt QEMU. > > Note: please apply the patch at [4] due to a regression introduced by > commit 596ff4a09b89 ("cpumask: re-introduce constant-sized cpumask > optimizations") before testing the series. > > Specail thanks to Conor and Vineet for kindly giving help on- and off-list. > > Source tree: > https://github.com/sifive/riscv-linux/tree/riscv/for-next/vector-v15 > > Links: > - [1] https://lore.kernel.org/all/20220921214439.1491510-17-stillson@rivosinc.com/ > - [2] https://lore.kernel.org/all/73c0124c-4794-6e40-460c-b26df407f322@rivosinc.com/T/#u > - [3] https://lore.kernel.org/all/20230128082847.3055316-1-apatel@ventanamicro.com/ > - [4] https://lore.kernel.org/all/CAHk-=wiAxtKyxs6BPEzirrXw1kXJ-7ZyGpgOrbzhmC=ud-6jBA@mail.gmail.com/ > --- > Changelog V15 > - Rebase to risc-v -next (v6.3-rc1) > - Make V depend on FD in Kconfig according to the spec and shut off v > properly. > - Fix a syntax error for clang build. But mark RISCV_ISA_V GAS only due > to https://reviews.llvm.org/D123515 > - Use scratch reg in inline asm instead of t4. > - Refine code. > - Cleanup per-patch changelogs. Andy, I think the series is in a good shape! Thanks for the hard work! To summarize; AFAIU the outstanding issues are: * sparse, patch 13 * Anup's KVM comments, patch 18 * Nathan's suggestion, patch 19 Anything else? If not, it would be amazing for a quick v16 turnaround, addressing the points above. Hopefully the next version can land in the upcoming release. Björn
This patchset is implemented based on vector 1.0 spec to add vector support in riscv Linux kernel. There are some assumptions for this implementations. 1. We assume all harts has the same ISA in the system. 2. We disable vector in both kernel andy user space [1] by default. Only enable an user's vector after an illegal instruction trap where it actually starts executing vector (the first-use trap [2]). 3. We detect "riscv,isa" to determine whether vector is support or not. We defined a new structure __riscv_v_ext_state in struct thread_struct to save/restore the vector related registers. It is used for both kernel space and user space. - In kernel space, the datap pointer in __riscv_v_ext_state will be allocated to save vector registers. - In user space, - In signal handler of user space, the structure is placed right after __riscv_ctx_hdr, which is embedded in fp reserved aera. This is required to avoid ABI break [2]. And datap points to the end of __riscv_v_ext_state. - In ptrace, the data will be put in ubuf in which we use riscv_vr_get()/riscv_vr_set() to get or set the __riscv_v_ext_state data structure from/to it, datap pointer would be zeroed and vector registers will be copied to the address right after the __riscv_v_ext_state structure in ubuf. This patchset is rebased to v6.3-rc1 and it is tested by running several vector programs simultaneously. It delivers signals correctly in a test where we can see a valid ucontext_t in a signal handler, and a correct V context returing back from it. And the ptrace interface is tested by PTRACE_{GET,SET}REGSET. Lastly, KVM is tested by running above tests in a guest using the same kernel image. All tests are done on an rv64gcv virt QEMU. Note: please apply the patch at [4] due to a regression introduced by commit 596ff4a09b89 ("cpumask: re-introduce constant-sized cpumask optimizations") before testing the series. Specail thanks to Conor and Vineet for kindly giving help on- and off-list. Source tree: https://github.com/sifive/riscv-linux/tree/riscv/for-next/vector-v15 Links: - [1] https://lore.kernel.org/all/20220921214439.1491510-17-stillson@rivosinc.com/ - [2] https://lore.kernel.org/all/73c0124c-4794-6e40-460c-b26df407f322@rivosinc.com/T/#u - [3] https://lore.kernel.org/all/20230128082847.3055316-1-apatel@ventanamicro.com/ - [4] https://lore.kernel.org/all/CAHk-=wiAxtKyxs6BPEzirrXw1kXJ-7ZyGpgOrbzhmC=ud-6jBA@mail.gmail.com/ --- Changelog V15 - Rebase to risc-v -next (v6.3-rc1) - Make V depend on FD in Kconfig according to the spec and shut off v properly. - Fix a syntax error for clang build. But mark RISCV_ISA_V GAS only due to https://reviews.llvm.org/D123515 - Use scratch reg in inline asm instead of t4. - Refine code. - Cleanup per-patch changelogs. Changelog V14 - Rebase to risc-v -next (v6.2-rc7) - Use TOOLCHAIN_HAS_V to detect if we can enable Vector. And refine KBUILD_CFLAGS to remove v from default compile option. - Drop illegal instruction handling patch in kvm and leave it to a independent series[3]. The series has merged into 6.3-rc1 - Move KVM_RISCV_ISA_EXT_V to the end of enum to prevent potential ABI breaks. - Use PT_SIZE_ON_STACK instead of PT_SIZE to fit alignment. Also, remove panic log from v13 (15/19) because it is no longer relevant. - Rewrite insn_is_vector for better structuring (change if-else chain to a switch) - Fix compilation error in the middle of the series - Validate size of the alternative signal frame if V is enabled whenever: - The user call sigaltstack to update altstack - A signal is being delivered - Rename __riscv_v_state to __riscv_v_ext_state. - Add riscv_v_ prefix and rename rvv appropriately - Organize riscv_v_vsize setup code into vector.c - Address the issue mentioned by Heiko on !FPU case - Honor orignal authors that got changed accidentally in v13 4,5,6 Changelog V13 - Rebase to latest risc-v next (v6.2-rc1) - vineetg: Re-organize the series to comply with bisect-ability - andy.chiu: Improve task switch with inline assembly - Re-structure the signal frame to avoid user ABI break. - Implemnt first-use trap and drop prctl for per-task V state enablement. Also, redirect this trap from hs to vs for kvm setup. - Do not expose V context in ptrace/sigframe until the task start using V. But still reserve V context for size ofsigframe reported by auxv. - Drop the kernel mode vector and leave it to another (future) series. Changelog V12 (Chris) - rebases to some point after v5.18-rc6 - add prctl to control per-process V state Chnagelog V10 - Rebase to v5.18-rc6 - Merge several patches - Refine codes - Fix bugs - Add kvm vector support Changelog V9 - Rebase to v5.15 - Merge several patches - Refine codes - Fix a kernel panic issue Changelog V8 - Rebase to v5.14 - Refine struct __riscv_v_ext_state with struct __riscv_ctx_hdr - Refine has_vector into a static key - Defined __reserved space in struct sigcontext for vector and future extensions Changelog V7 - Add support for kernel mode vector - Add vector extension XOR implementation - Optimize task switch codes of vector - Allocate space for vector registers in start_thread() - Fix an illegal instruction exception when accessing vlenb - Optimize vector registers initialization - Initialize vector registers with proper vsetvli then it can work normally - Refine ptrace porting due to generic API changed - Code clean up Changelog V6 - Replace vle.v/vse.v instructions with vle8.v/vse8.v based on 0.9 spec - Add comments based on mailinglist feedback - Fix rv32 build error Changelog V5 - Using regset_size() correctly in generic ptrace - Fix the ptrace porting - Fix compile warning Changelog V4 - Support dynamic vlen - Fix bugs: lazy save/resotre, not saving vtype - Update VS bit offset based on latest vector spec - Add new vector csr based on latest vector spec - Code refine and removed unused macros Changelog V3 - Rebase linux-5.6-rc3 and tested with qemu - Seperate patches with Anup's advice - Give out a ABI puzzle with unlimited vlen Changelog V2 - Fixup typo "vecotr, fstate_save->vstate_save". - Fixup wrong saved registers' length in vector.S. - Seperate unrelated patches from this one. Andy Chiu (3): riscv: Allocate user's vector context in the first-use trap riscv: signal: check fp-reserved words unconditionally riscv: signal: validate altstack to reflect Vector Greentime Hu (9): riscv: Add new csr defines related to vector extension riscv: Clear vector regfile on bootup riscv: Introduce Vector enable/disable helpers riscv: Introduce riscv_v_vsize to record size of Vector context riscv: Introduce struct/helpers to save/restore per-task Vector state riscv: Add task switch support for vector riscv: Add ptrace vector support riscv: signal: Add sigcontext save/restore for vector riscv: prevent stack corruption by reserving task_pt_regs(p) early Guo Ren (4): riscv: Rename __switch_to_aux() -> fpu riscv: Extending cpufeature.c to detect V-extension riscv: Disable Vector Instructions for kernel itself riscv: Enable Vector code to be built Vincent Chen (3): riscv: signal: Report signal frame size to userspace via auxv riscv: kvm: Add V extension to KVM ISA riscv: KVM: Add vector lazy save/restore support arch/riscv/Kconfig | 20 ++ arch/riscv/Makefile | 6 +- arch/riscv/include/asm/csr.h | 18 +- arch/riscv/include/asm/elf.h | 9 + arch/riscv/include/asm/hwcap.h | 1 + arch/riscv/include/asm/insn.h | 29 +++ arch/riscv/include/asm/kvm_host.h | 2 + arch/riscv/include/asm/kvm_vcpu_vector.h | 77 ++++++++ arch/riscv/include/asm/processor.h | 3 + arch/riscv/include/asm/switch_to.h | 9 +- arch/riscv/include/asm/thread_info.h | 3 + arch/riscv/include/asm/vector.h | 179 ++++++++++++++++++ arch/riscv/include/uapi/asm/auxvec.h | 1 + arch/riscv/include/uapi/asm/hwcap.h | 1 + arch/riscv/include/uapi/asm/kvm.h | 8 + arch/riscv/include/uapi/asm/ptrace.h | 39 ++++ arch/riscv/include/uapi/asm/sigcontext.h | 16 +- arch/riscv/kernel/Makefile | 1 + arch/riscv/kernel/cpufeature.c | 13 ++ arch/riscv/kernel/entry.S | 6 +- arch/riscv/kernel/head.S | 41 ++++- arch/riscv/kernel/process.c | 18 ++ arch/riscv/kernel/ptrace.c | 70 +++++++ arch/riscv/kernel/setup.c | 3 + arch/riscv/kernel/signal.c | 221 ++++++++++++++++++++--- arch/riscv/kernel/traps.c | 14 +- arch/riscv/kernel/vector.c | 111 ++++++++++++ arch/riscv/kvm/Makefile | 1 + arch/riscv/kvm/vcpu.c | 31 ++++ arch/riscv/kvm/vcpu_vector.c | 177 ++++++++++++++++++ include/uapi/linux/elf.h | 1 + 31 files changed, 1081 insertions(+), 48 deletions(-) create mode 100644 arch/riscv/include/asm/kvm_vcpu_vector.h create mode 100644 arch/riscv/include/asm/vector.h create mode 100644 arch/riscv/kernel/vector.c create mode 100644 arch/riscv/kvm/vcpu_vector.c