Re: [PATCH 5/7] KVM: MMU: document fast page fault in

From: Paolo Bonzini
Date: Wed Jun 19 2013 - 08:14:11 EST


Il 19/06/2013 11:09, Xiao Guangrong ha scritto:
> Document fast page fault to Documentation/virtual/kvm/mmu.txt
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
> ---
> Documentation/virtual/kvm/mmu.txt | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt
> index 4fb442b..b5ce7dd 100644
> --- a/Documentation/virtual/kvm/mmu.txt
> +++ b/Documentation/virtual/kvm/mmu.txt
> @@ -275,6 +275,9 @@ Handling a page fault is performed as follows:
> information is stored and cache the information to vcpu->arch.mmio_gva,
> vcpu->arch.access and vcpu->arch.mmio_gfn then call the emulator to emulate
> the instruction who will get the benefit from the cached mmio info
> + - If both P bit and R/W bit of error code are set, there has a chance to
> + fast fix the page fault, please see the description of "Fast page fault" in
> + Documentation/virtual/kvm/locking.txt

- If both P bit and R/W bit of error code are set, this could possibly
be handled as a "fast page fault" (fixed without taking the MMU lock). See
the description in Documentation/virtual/kvm/locking.txt.

Paolo

> - if needed, walk the guest page tables to determine the guest translation
> (gva->gpa or ngpa->gpa)
> - if permissions are insufficient, reflect the fault back to the guest
>

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