[PATCH v7 07/14] KVM: Use gfn instead of hva for mmu_notifier_retry

Chao Peng
2022-07-06T08:25:19Z

Currently in mmu_notifier validate path, hva range is recorded and then
checked in the mmu_notifier_retry_hva() from page fault path. However
for the to be introduced private memory, a page fault may not have a hva
associated, checking gfn(gpa) makes more sense. For existing non private
memory case, gfn is expected to continue to work.

The patch also fixes a potential bug in kvm_zap_gfn_range() which has
already been using gfn when calling kvm_inc/dec_notifier_count() in
current code.

Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
arch/x86/kvm/mmu/mmu.c | 2 +-
include/linux/kvm_host.h | 18 ++++++++----------
virt/kvm/kvm_main.c | 6 +++---
3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index f7fa4c31b7c5..0d882fad4bc1 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4182,7 +4182,7 @@ static bool is_page_fault_stale(struct kvm_vcpu *vcpu,
return true;

return fault->slot &&
- mmu_notifier_retry_hva(vcpu->kvm, mmu_seq, fault->hva);
+ mmu_notifier_retry_gfn(vcpu->kvm, mmu_seq, fault->gfn);
}

static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0bdb6044e316..e9153b54e2a4 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -767,8 +767,8 @@ struct kvm {
struct mmu_notifier mmu_notifier;
unsigned long mmu_notifier_seq;
long mmu_notifier_count;
- unsigned long mmu_notifier_range_start;
- unsigned long mmu_notifier_range_end;
+ gfn_t mmu_notifier_range_start;
+ gfn_t mmu_notifier_range_end;
#endif
struct list_head devices;
u64 manual_dirty_log_protect;
@@ -1362,10 +1362,8 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc);
void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
#endif

-void kvm_inc_notifier_count(struct kvm *kvm, unsigned long start,
- unsigned long end);
-void kvm_dec_notifier_count(struct kvm *kvm, unsigned long start,
- unsigned long end);
+void kvm_inc_notifier_count(struct kvm *kvm, gfn_t start, gfn_t end);
+void kvm_dec_notifier_count(struct kvm *kvm, gfn_t start, gfn_t end);

long kvm_arch_dev_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg);
@@ -1923,9 +1921,9 @@ static inline int mmu_notifier_retry(struct kvm *kvm, unsigned long mmu_seq)
return 0;
}

-static inline int mmu_notifier_retry_hva(struct kvm *kvm,
+static inline int mmu_notifier_retry_gfn(struct kvm *kvm,
unsigned long mmu_seq,
- unsigned long hva)
+ gfn_t gfn)
{
lockdep_assert_held(&kvm->mmu_lock);
/*
@@ -1935,8 +1933,8 @@ static inline int mmu_notifier_retry_hva(struct kvm *kvm,
* positives, due to shortcuts when handing concurrent invalidations.
*/
if (unlikely(kvm->mmu_notifier_count) &&
- hva >= kvm->mmu_notifier_range_start &&
- hva < kvm->mmu_notifier_range_end)
+ gfn >= kvm->mmu_notifier_range_start &&
+ gfn < kvm->mmu_notifier_range_end)
return 1;
if (kvm->mmu_notifier_seq != mmu_seq)
return 1;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index da263c370d00..4d7f0e72366f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -536,8 +536,7 @@ static void kvm_mmu_notifier_invalidate_range(struct mmu_notifier *mn,

typedef bool (*hva_handler_t)(struct kvm *kvm, struct kvm_gfn_range *range);

-typedef void (*on_lock_fn_t)(struct kvm *kvm, unsigned long start,
- unsigned long end);
+typedef void (*on_lock_fn_t)(struct kvm *kvm, gfn_t start, gfn_t end);

typedef void (*on_unlock_fn_t)(struct kvm *kvm);

@@ -624,7 +623,8 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
locked = true;
KVM_MMU_LOCK(kvm);
if (!IS_KVM_NULL_FN(range->on_lock))
- range->on_lock(kvm, range->start, range->end);
+ range->on_lock(kvm, gfn_range.start,
+ gfn_range.end);
if (IS_KVM_NULL_FN(range->handler))
break;
}
--
2.25.1