Re: [RFC PATCH 4/6] KVM: arm64: Optimize TLBIs in the dirty logging path
From: Oliver Upton <hidden>
Date: 2023-01-24 22:54:22
Also in:
kvm, kvmarm, lkml
Hi Raghavendra, I find the commit title rather ambiguous. May I suggest: KVM: arm64: Use range-based TLBIs for write protection On Mon, Jan 09, 2023 at 09:53:45PM +0000, Raghavendra Rao Ananta wrote:
Currently the dirty-logging paths, including kvm_arch_flush_remote_tlbs_memslot() and kvm_mmu_wp_memory_region() ivalidates the entire VM's TLB entries using kvm_flush_remote_tlbs(). As the range of IPAs is provided by these functions, this is highly inefficient on the systems which support FEAT_TLBIRANGE. Hence, use kvm_flush_remote_tlbs_range() to flush the TLBs instead.
This commit message gives a rather mechanical description of the commit. Instead of describing the change, could you describe _why_ this is an improvement over the VM-wide invalidation? -- Thanks, Oliver
quoted hunk ↗ jump to hunk
Signed-off-by: Raghavendra Rao Ananta <redacted> --- arch/arm64/kvm/arm.c | 7 ++++++- arch/arm64/kvm/mmu.c | 2 +- 2 files changed, 7 insertions(+), 2 deletions(-)diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 00da570ed72bd..179520888c697 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c@@ -1433,7 +1433,12 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot) void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm, const struct kvm_memory_slot *memslot) { - kvm_flush_remote_tlbs(kvm); + phys_addr_t start, end; + + start = memslot->base_gfn << PAGE_SHIFT; + end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT; + + kvm_flush_remote_tlbs_range(kvm, start, end); } static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 70f76bc909c5d..e34b81f5922ce 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c@@ -976,7 +976,7 @@ static void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot) write_lock(&kvm->mmu_lock); stage2_wp_range(&kvm->arch.mmu, start, end); write_unlock(&kvm->mmu_lock); - kvm_flush_remote_tlbs(kvm); + kvm_flush_remote_tlbs_range(kvm, start, end); } /**-- 2.39.0.314.g84b9a713c41-goog
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