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KVM: MMU: fast invalidate all mmio sptes

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This patch tries to introduce a very simple and scale way to invalidate
all mmio sptes - it need not walk any shadow pages and hold mmu-lock

KVM maintains a global mmio valid generation-number which is stored in
kvm->memslots.generation and every mmio spte stores the current global
generation-number into his available bits when it is created

When KVM need zap all mmio sptes, it just simply increase the global
generation-number. When guests do mmio access, KVM intercepts a MMIO #PF
then it walks the shadow page table and get the mmio spte. If the
generation-number on the spte does not equal the global generation-number,
it will go to the normal #PF handler to update the mmio spte

Since 19 bits are used to store generation-number on mmio spte, we zap all
mmio sptes when the number is round

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Xiao Guangrong
2013-06-07 16:51:26 +08:00
committed by Gleb Natapov
parent b37fbea6ce
commit f8f559422b
6 changed files with 61 additions and 14 deletions
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4
arch/x86/kvm/vmx.c
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@@ -5369,6 +5369,10 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
if (likely(ret == RET_MMIO_PF_EMULATE))
return x86_emulate_instruction(vcpu, gpa, 0, NULL, 0) ==
EMULATE_DONE;
if (unlikely(ret == RET_MMIO_PF_INVALID))
return kvm_mmu_page_fault(vcpu, gpa, 0, NULL, 0);
if (unlikely(ret == RET_MMIO_PF_RETRY))
return 1;