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KVM: x86/mmu: Skip remote TLB flush when zapping all of TDP MMU

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Don't flush the TLBs when zapping all TDP MMU pages, as the only time KVM
uses the slow version of "zap everything" is when the VM is being
destroyed or the owning mm has exited.  In either case, KVM_RUN is
unreachable for the VM, i.e. the guest TLB entries cannot be consumed.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-15-seanjc@google.com>
Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-02-26 00:15:32 +00:00 committed by Paolo Bonzini
parent c10743a182
commit 77c8cd6b85
1 changed files with 6 additions and 5 deletions
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11
arch/x86/kvm/mmu/tdp_mmu.c
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@ -860,14 +860,15 @@ bool __kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, gfn_t start,
void kvm_tdp_mmu_zap_all(struct kvm *kvm)
{
bool flush = false;
int i;
/*
* A TLB flush is unnecessary, KVM zaps everything if and only the VM
* is being destroyed or the userspace VMM has exited. In both cases,
* KVM_RUN is unreachable, i.e. no vCPUs will ever service the request.
*/
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, 0, -1ull, flush);
if (flush)
kvm_flush_remote_tlbs(kvm);
(void)kvm_tdp_mmu_zap_gfn_range(kvm, i, 0, -1ull, false);
}
static struct kvm_mmu_page *next_invalidated_root(struct kvm *kvm,