On Fri, Jun 11, 2021 at 11:56:58PM +0000, David Matlack wrote:
> In order to use walk_shadow_page_lockless() in fast_page_fault() we need
> to also record the spteps.
>
> No functional change intended.
>
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
> arch/x86/kvm/mmu/mmu.c | 1 +
> arch/x86/kvm/mmu/mmu_internal.h | 3 +++
> arch/x86/kvm/mmu/tdp_mmu.c | 1 +
> 3 files changed, 5 insertions(+)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 8140c262f4d3..765f5b01768d 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -3538,6 +3538,7 @@ static bool walk_shadow_page_lockless(struct kvm_vcpu *vcpu, u64 addr,
> spte = mmu_spte_get_lockless(it.sptep);
> walk->last_level = it.level;
> walk->sptes[it.level] = spte;
> + walk->spteps[it.level] = it.sptep;
>
> if (!is_shadow_present_pte(spte))
> break;
> diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
> index 26da6ca30fbf..0fefbd5d6c95 100644
> --- a/arch/x86/kvm/mmu/mmu_internal.h
> +++ b/arch/x86/kvm/mmu/mmu_internal.h
> @@ -178,6 +178,9 @@ struct shadow_page_walk {
>
> /* The spte value at each level. */
> u64 sptes[PT64_ROOT_MAX_LEVEL + 1];
> +
> + /* The spte pointers at each level. */
> + u64 *spteps[PT64_ROOT_MAX_LEVEL + 1];
> };
>
> #endif /* __KVM_X86_MMU_INTERNAL_H */
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 36f4844a5f95..7279d17817a1 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -1529,6 +1529,7 @@ bool kvm_tdp_mmu_walk_lockless(struct kvm_vcpu *vcpu, u64 addr,
>
> walk->last_level = iter.level;
> walk->sptes[iter.level] = iter.old_spte;
> + walk->spteps[iter.level] = iter.sptep;
I think this should technically be:
walk->spteps[iter.level] = rcu_dereference(iter.sptep);
> }
>
> return walk_ok;
> --
> 2.32.0.272.g935e593368-goog
>
