Re: [PATCH 01/14] KVM: x86/mmu: Expand collapsible SPTE zap for TDP MMU to ZONE_DEVICE pages

Paolo Bonzini
2021-02-18T16:06:19Z

On 13/02/21 01:50, Sean Christopherson wrote:
> Zap SPTEs that are backed by ZONE_DEVICE pages when zappings SPTEs to
> rebuild them as huge pages in the TDP MMU. ZONE_DEVICE huge pages are
> managed differently than "regular" pages and are not compound pages.
>
> Cc: Ben Gardon <bgardon@google.com>
> Fixes: 14881998566d ("kvm: x86/mmu: Support disabling dirty logging for the tdp MMU")
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/mmu/tdp_mmu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 71e100a5670f..3cc332ed099d 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -1348,7 +1348,8 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
>
> pfn = spte_to_pfn(iter.old_spte);
> if (kvm_is_reserved_pfn(pfn) ||
> - !PageTransCompoundMap(pfn_to_page(pfn)))
> + (!PageTransCompoundMap(pfn_to_page(pfn)) &&
> + !kvm_is_zone_device_pfn(pfn)))
> continue;
>
> tdp_mmu_set_spte(kvm, &iter, 0);
>

I added a note to the commit message that a similar check is found in
kvm_mmu_zap_collapsible_spte.

Paolo