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SubjectRe: [RESEND PATCH v5 10/11] KVM: arm64: Invalidate the table entries upon a range
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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);
>

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