On Thu, Sep 08, 2022 at 01:43:54AM +0800, David Matlack wrote:
> On Wed, Aug 24, 2022 at 05:29:18PM +0800, 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.
> >
> > 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 | 10 +++++++++-
> > 1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index e418ef3ecfcb..a3578abd8bbc 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -260,6 +260,14 @@ 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_with_address(kvm, sp->gfn,
> > + KVM_PAGES_PER_HPAGE(sp->role.level + 1));
>
> nit: I think it would make sense to introduce
> kvm_flush_remote_tlbs_gfn() in this patch since you are going to
> eventually use it here anyway.
>
OK, I'll do it in the next version. Thanks!
> > +}
> > +
> > static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn,
> > unsigned int access)
> > {
> > @@ -2341,7 +2349,7 @@ 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);
> > }
> > }
> >
> > --
> > 2.31.1
> >
