On Wed, Jul 27, 2022 at 06:59:20AM +0800, David Matlack wrote:
> On Fri, Jun 24, 2022 at 11:36:56AM +0800, Hou Wenlong wrote:
> > Commit c3134ce240eed
> > ("KVM: Replace old tlb flush function with new one to flush a specified range.")
> > replaces old tlb flush function with kvm_flush_remote_tlbs_with_address()
> > to do tlb flushing. However, the gfn range of tlb flushing is wrong in
> > some cases. E.g., when a spte is dropped, the start gfn of tlb flushing
> > should be the gfn of spte not the base gfn of SP which contains the spte.
> > So this patchset would fix them and do some cleanups.
>
> One thing that would help prevent future buggy use of
> kvm_flush_remote_tlbs_with_address(), and clean up this series, would be to
> introduce some helper functions for common operations. In fact, even if
> there is only one caller, I still think it would be useful to have helper
> functions because it makes it clear the author's intent.
>
> For example, I think the following helpers would be useful in this series:
>
> /* Flush the given page (huge or not) of guest memory. */
> static void kvm_flush_remote_tlbs_gfn(struct kvm *kvm, gfn_t gfn, int level)
> {
> u64 pages = KVM_PAGES_PER_HPAGE(level);
>
> kvm_flush_remote_tlbs_with_address(kvm, gfn, pages);
> }
>
> /* Flush the range of guest memory mapped by the given SPTE. */
> static void kvm_flush_remote_tlbs_sptep(struct kvm *kvm, u64 *sptep)
> {
> struct kvm_mmu_page *sp = sptep_to_sp(sptep);
> gfn_t gfn = kvm_mmu_page_get_gfn(sp, spte_index(sptep));
>
> kvm_flush_remote_tlbs_gfn(kvm, gfn, sp->role.level);
> }
>
> /* 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);
> }
>
Thanks for your good suggestions, I'll add those helpers in the next version.
> >
> > Hou Wenlong (5):
> > KVM: x86/mmu: Fix wrong gfn range of tlb flushing in
> > validate_direct_spte()
> > KVM: x86/mmu: Fix wrong gfn range of tlb flushing in
> > kvm_set_pte_rmapp()
> > KVM: x86/mmu: Reduce gfn range of tlb flushing in
> > tdp_mmu_map_handle_target_level()
> > KVM: x86/mmu: Fix wrong start gfn of tlb flushing with range
> > KVM: x86/mmu: Use 1 as the size of gfn range for tlb flushing in
> > FNAME(invlpg)()
> >
> > arch/x86/kvm/mmu/mmu.c | 15 +++++++++------
> > arch/x86/kvm/mmu/paging_tmpl.h | 2 +-
> > arch/x86/kvm/mmu/tdp_mmu.c | 4 ++--
> > 3 files changed, 12 insertions(+), 9 deletions(-)
> >
> > --
> > 2.31.1
> >
