lkml.org 
[lkml]   [2023]   [Feb]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 1/7] kvm: x86/mmu: Use KVM_MMU_ROOT_XXX for kvm_mmu_invalidate_gva()
On Thu, Feb 2, 2023 at 9:21 AM Sean Christopherson <seanjc@google.com> wrote:

>
> This is logically correct, but there's potential (weird) functional change here.
> If this is called with an invalid root, then KVM will invalidate the GVA in all
> roots prior to this patch, but in no roots after this patch.
>
> I _think_ it should be impossible get here with an invalid root. Can you try
> adding a prep patch to assert that the root is valid so that this patch can
> reasonably assert that there's no functional change?
>
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 508074e47bc0..fffd9b610196 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -792,6 +792,8 @@ void kvm_inject_emulated_page_fault(struct kvm_vcpu *vcpu,
> fault_mmu = fault->nested_page_fault ? vcpu->arch.mmu :
> vcpu->arch.walk_mmu;
>
> + WARN_ON_ONCE(!VALID_PAGE(fault_mmu->root.hpa));
> +

I've been updating the patches as per your suggestions.

And I suddenly realized that when fault->nested_page_fault=false
with nested EPT, fault_mmu->root.hpa is always unset.

fault_mmu->root.hpa is just meaningless when fault_mmu is not
vcpu->arch.mmu.

I will add it as one of the reasons for replacing the argument
with KVM_MMU_ROOT_XXX.

> /*
> * Invalidate the TLB entry for the faulting address, if it exists,
> * else the access will fault indefinitely (and to emulate hardware).
>

\
 
 \ /
  Last update: 2023-03-27 00:09    [W:0.751 / U:0.052 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site