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| author | Dong Yang <dayss1224@gmail.com> | 2025-11-03 14:28:25 +0800 |
|---|---|---|
| committer | Anup Patel <anup@brainfault.org> | 2025-11-24 09:55:36 +0530 |
| commit | df60cb2e67029e07e23c4fdf9e027aaf1f63cc1a (patch) | |
| tree | 3ba4f1cc77c15e59d6a7d0117745a0c5ec2a9a41 | |
| parent | a2483d5d1ee9b399d8137691cb0d8dc99cfe7684 (diff) | |
KVM: riscv: Support enabling dirty log gradually in small chunks
There is already support of enabling dirty log gradually in small chunks
for x86 in commit 3c9bd4006bfc ("KVM: x86: enable dirty log gradually in
small chunks") and c862626 ("KVM: arm64: Support enabling dirty log
gradually in small chunks"). This adds support for riscv.
x86 and arm64 writes protect both huge pages and normal pages now, so
riscv protect also protects both huge pages and normal pages.
On a nested virtualization setup (RISC-V KVM running inside a QEMU VM
on an [Intel® Core™ i5-12500H] host), I did some tests with a 2G Linux
VM using different backing page sizes. The time taken for
memory_global_dirty_log_start in the L2 QEMU is listed below:
Page Size Before After Optimization
4K 4490.23ms 31.94ms
2M 48.97ms 45.46ms
1G 28.40ms 30.93ms
Signed-off-by: Quan Zhou <zhouquan@iscas.ac.cn>
Signed-off-by: Dong Yang <dayss1224@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251103062825.9084-1-dayss1224@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 2 | ||||
| -rw-r--r-- | arch/riscv/include/asm/kvm_host.h | 3 | ||||
| -rw-r--r-- | arch/riscv/kvm/mmu.c | 5 |
3 files changed, 8 insertions, 2 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 57061fa29e6a..3b621c3ae67c 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -8028,7 +8028,7 @@ will be initialized to 1 when created. This also improves performance because dirty logging can be enabled gradually in small chunks on the first call to KVM_CLEAR_DIRTY_LOG. KVM_DIRTY_LOG_INITIALLY_SET depends on KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE (it is also only available on -x86 and arm64 for now). +x86, arm64 and riscv for now). KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 was previously available under the name KVM_CAP_MANUAL_DIRTY_LOG_PROTECT, but the implementation had bugs that make diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h index 4d794573e3db..e30548a4ab60 100644 --- a/arch/riscv/include/asm/kvm_host.h +++ b/arch/riscv/include/asm/kvm_host.h @@ -59,6 +59,9 @@ BIT(IRQ_VS_TIMER) | \ BIT(IRQ_VS_EXT)) +#define KVM_DIRTY_LOG_MANUAL_CAPS (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | \ + KVM_DIRTY_LOG_INITIALLY_SET) + struct kvm_vm_stat { struct kvm_vm_stat_generic generic; }; diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c index 58f5f3536ffd..4ab06697bfc0 100644 --- a/arch/riscv/kvm/mmu.c +++ b/arch/riscv/kvm/mmu.c @@ -161,8 +161,11 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, * allocated dirty_bitmap[], dirty pages will be tracked while * the memory slot is write protected. */ - if (change != KVM_MR_DELETE && new->flags & KVM_MEM_LOG_DIRTY_PAGES) + if (change != KVM_MR_DELETE && new->flags & KVM_MEM_LOG_DIRTY_PAGES) { + if (kvm_dirty_log_manual_protect_and_init_set(kvm)) + return; mmu_wp_memory_region(kvm, new->id); + } } int kvm_arch_prepare_memory_region(struct kvm *kvm, |