| Message ID | 20230621175002.2832640-11-rananta@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: Add support for FEAT_TLBIRANGE | expand |
On 6/22/23 03:50, Raghavendra Rao Ananta wrote: > Currently, during the operations such as a hugepage collapse, > KVM would flush the entire VM's context using 'vmalls12e1is' > TLBI operation. Specifically, if the VM is faulting on many > hugepages (say after dirty-logging), it creates a performance > penalty for the guest whose pages have already been faulted > earlier as they would have to refill their TLBs again. > > Instead, leverage kvm_tlb_flush_vmid_range() for table entries. > If the system supports it, only the required range will be > flushed. Else, it'll fallback to the previous mechanism. > > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> > --- > arch/arm64/kvm/hyp/pgtable.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > Reviewed-by: Gavin Shan <gshan@redhat.com> > diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c > index df8ac14d9d3d4..50ef7623c54db 100644 > --- a/arch/arm64/kvm/hyp/pgtable.c > +++ b/arch/arm64/kvm/hyp/pgtable.c > @@ -766,7 +766,8 @@ static bool stage2_try_break_pte(const struct kvm_pgtable_visit_ctx *ctx, > * value (if any). > */ > if (kvm_pte_table(ctx->old, ctx->level)) > - kvm_call_hyp(__kvm_tlb_flush_vmid, mmu); > + kvm_tlb_flush_vmid_range(mmu, ctx->addr, > + kvm_granule_size(ctx->level)); > else if (kvm_pte_valid(ctx->old)) > kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, ctx->addr, ctx->level); >
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c index df8ac14d9d3d4..50ef7623c54db 100644 --- a/arch/arm64/kvm/hyp/pgtable.c +++ b/arch/arm64/kvm/hyp/pgtable.c @@ -766,7 +766,8 @@ static bool stage2_try_break_pte(const struct kvm_pgtable_visit_ctx *ctx, * value (if any). */ if (kvm_pte_table(ctx->old, ctx->level)) - kvm_call_hyp(__kvm_tlb_flush_vmid, mmu); + kvm_tlb_flush_vmid_range(mmu, ctx->addr, + kvm_granule_size(ctx->level)); else if (kvm_pte_valid(ctx->old)) kvm_call_hyp(__kvm_tlb_flush_vmid_ipa, mmu, ctx->addr, ctx->level);
Currently, during the operations such as a hugepage collapse, KVM would flush the entire VM's context using 'vmalls12e1is' TLBI operation. Specifically, if the VM is faulting on many hugepages (say after dirty-logging), it creates a performance penalty for the guest whose pages have already been faulted earlier as they would have to refill their TLBs again. Instead, leverage kvm_tlb_flush_vmid_range() for table entries. If the system supports it, only the required range will be flushed. Else, it'll fallback to the previous mechanism. Signed-off-by: Raghavendra Rao Ananta <rananta@google.com> --- arch/arm64/kvm/hyp/pgtable.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)