[PW_SID:1123039] RISC-V: KVM: Optimize hfence request handling for SMP guests by linux-riscv-bot · Pull Request #2235 · linux-riscv/linux

linux-riscv-bot · 2026-07-07T12:50:44Z

PR for series 1123039 applied to workflow__riscv__fixes

Name: RISC-V: KVM: Optimize hfence request handling for SMP guests
URL: https://patchwork.kernel.org/project/linux-riscv/list/?series=1123039
Version: 1

Currently, the check for `data` and `data->type` is performed inside the loop iterating over each VCPU. Since these values are invariant during the loop, this check is redundant and adds unnecessary overhead. Move the validation to the beginning of the function, returning early if the hfence data or its type is invalid. This avoids repeated checks and reduces CPU cycles, which is particularly beneficial for SMP guests with a large number of VCPUs. Signed-off-by: Wang Yechao <wang.yechao255@zte.com.cn> Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>

When handling hfence requests in make_xfence_request(), the current code uses a single 'actual_req' variable and a single vcpu_mask. If any VCPU fails to enqueue the hfence data (because its queue is full), the request falls back to 'fallback_req' for all VCPUs, even if other VCPUs still have available queue space. This can cause unnecessary fallback for healthy VCPUs, and more seriously, those healthy VCPUs will not process their already-enqueued hfence requests because no 'req' is set for them. As a result, their queues will quickly become full as well, degrading performance for SMP guests. Fix this by maintaining two separate bitmaps: one for VCPUs that successfully enqueued the hfence data (req_vcpu_mask) and another for those that failed (fallback_req_vcpu_mask). Then send the appropriate requests to each group. This ensures that fallback is only applied to VCPUs that actually need it, preserving the efficiency of the normal path for others. Fixes: 13acfec ("RISC-V: KVM: Add remote HFENCE functions based on VCPU requests") Signed-off-by: Wang Yechao <wang.yechao255@zte.com.cn> Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>

linux-riscv-bot · 2026-07-07T12:56:53Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
build-rv32-defconfig
Desc: Builds riscv32 defconfig
Duration: 143.29 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:16:08Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
build-rv64-clang-allmodconfig
Desc: Builds riscv64 allmodconfig with Clang, and checks for errors and added warnings
Duration: 1153.34 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:40:18Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
build-rv64-gcc-allmodconfig
Desc: Builds riscv64 allmodconfig with GCC, and checks for errors and added warnings
Duration: 1447.96 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:40:46Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
build-rv64-nommu-k210-defconfig
Desc: Builds riscv64 defconfig with NOMMU for K210
Duration: 25.99 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:41:15Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
build-rv64-nommu-k210-virt
Desc: Builds riscv64 defconfig with NOMMU for the virt platform
Duration: 27.18 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:41:17Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
checkpatch
Desc: Runs checkpatch.pl on the patch
Duration: 0.74 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:42:43Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
dtb-warn-rv64
Desc: Checks for Device Tree warnings/errors
Duration: 84.46 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:42:45Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
header-inline
Desc: Detects static functions without inline keyword in header files
Duration: 0.23 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:42:48Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
kdoc
Desc: Detects for kdoc errors
Duration: 0.80 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:42:50Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
module-param
Desc: Detect module_param changes
Duration: 0.25 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:42:52Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
verify-fixes
Desc: Verifies that the Fixes: tags exist
Duration: 0.22 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:42:54Z

Patch 1: "[1/2] RISC-V: KVM: Move hfence type check out of loop"
verify-signedoff
Desc: Verifies that Signed-off-by: tags are correct
Duration: 0.30 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T13:45:33Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
build-rv32-defconfig
Desc: Builds riscv32 defconfig
Duration: 144.18 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:04:54Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
build-rv64-clang-allmodconfig
Desc: Builds riscv64 allmodconfig with Clang, and checks for errors and added warnings
Duration: 1159.01 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:29:10Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
build-rv64-gcc-allmodconfig
Desc: Builds riscv64 allmodconfig with GCC, and checks for errors and added warnings
Duration: 1453.99 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:29:38Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
build-rv64-nommu-k210-defconfig
Desc: Builds riscv64 defconfig with NOMMU for K210
Duration: 26.25 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:30:07Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
build-rv64-nommu-k210-virt
Desc: Builds riscv64 defconfig with NOMMU for the virt platform
Duration: 27.93 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:30:10Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
checkpatch
Desc: Runs checkpatch.pl on the patch
Duration: 1.03 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:31:37Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
dtb-warn-rv64
Desc: Checks for Device Tree warnings/errors
Duration: 84.92 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:31:39Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
header-inline
Desc: Detects static functions without inline keyword in header files
Duration: 0.25 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:31:41Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
kdoc
Desc: Detects for kdoc errors
Duration: 0.87 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:31:43Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
module-param
Desc: Detect module_param changes
Duration: 0.26 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:31:45Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
verify-fixes
Desc: Verifies that the Fixes: tags exist
Duration: 0.29 seconds
Result: PASS

linux-riscv-bot · 2026-07-07T14:31:47Z

Patch 2: "[2/2] RISC-V: KVM: Separate req and fallback_req masks in make_xfence_request"
verify-signedoff
Desc: Verifies that Signed-off-by: tags are correct
Duration: 0.32 seconds
Result: PASS

yechao-w added 2 commits July 7, 2026 12:50

linux-riscv-bot closed this Jul 7, 2026

linux-riscv-bot deleted the pw1123039 branch July 7, 2026 15:49

Uh oh!

Conversation

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

linux-riscv-bot commented Jul 7, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants