| Message ID | 4c4c0943f431e760a51ec0d45e3979c38820749f.1663929851.git.houwenlong.hwl@antgroup.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86/mmu: Fix wrong usages of range-based tlb flushing | expand |
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@google.com> > Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com> > --- > 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@google.com
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); } } diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index 582def531d4d..6651c154f2e0 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -163,8 +163,18 @@ void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn); bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, struct kvm_memory_slot *slot, u64 gfn, int min_level); + void kvm_flush_remote_tlbs_with_address(struct kvm *kvm, u64 start_gfn, u64 pages); + +/* Flush the given page (huge or not) of guest memory. */ +static inline 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); +} + unsigned int pte_list_count(struct kvm_rmap_head *rmap_head); extern int nx_huge_pages;
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@google.com> Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com> --- arch/x86/kvm/mmu/mmu.c | 9 ++++++++- arch/x86/kvm/mmu/mmu_internal.h | 10 ++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-)