On Fri, Sep 23, 2022, Hou Wenlong wrote:
> The spte pointing to the children SP is dropped, so the
> whole gfn range covered by the children SP should be flushed.
> Although, Hyper-V may treat a 1-page flush the same if the
> address points to a huge page, it still would be better
> to use the correct size of huge page. Also introduce
> a helper function to do range-based flushing when a direct
> SP is dropped, which would help prevent future buggy use
> of kvm_flush_remote_tlbs_with_address() in such case.
Please wrap closer to ~75 chars.
> Fixes: c3134ce240eed ("KVM: Replace old tlb flush function with new one to flush a specified range.")
> Suggested-by: David Matlack <dmatlack@xxxxxxxxxx>
> Signed-off-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx>
> ---
> arch/x86/kvm/mmu/mmu.c | 9 ++++++++-
> arch/x86/kvm/mmu/mmu_internal.h | 10 ++++++++++
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index e418ef3ecfcb..ae9f84b0fc64 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -260,6 +260,13 @@ void kvm_flush_remote_tlbs_with_address(struct kvm *kvm,
> kvm_flush_remote_tlbs_with_range(kvm, &range);
> }
>
> +/* Flush all memory mapped by the given direct SP. */
> +static void kvm_flush_remote_tlbs_direct_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
> +{
> + WARN_ON_ONCE(!sp->role.direct);
> + kvm_flush_remote_tlbs_gfn(kvm, sp->gfn, sp->role.level + 1);
> +}
> +
> static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn,
> unsigned int access)
> {
> @@ -2341,7 +2348,7 @@ static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
> return;
>
> drop_parent_pte(child, sptep);
> - kvm_flush_remote_tlbs_with_address(vcpu->kvm, child->gfn, 1);
> + kvm_flush_remote_tlbs_direct_sp(vcpu->kvm, child);
As mentioned very belatedly[*], I would rather move this patch later in the series
and use kvm_flush_remote_tlbs_sptep() instead of introducing a one-off helper.
[*] https://lore.kernel.org/all/YzMoWghqNJdYBlaE@xxxxxxxxxx
