The memslot for the faulting gfn is used throughout the page fault
handling code, so capture it in kvm_page_fault as soon as we know the
gfn and use it in the page fault handling code that has direct access
to the kvm_page_fault struct.
This, in combination with the subsequent patch, improves "Populate
memory time" in dirty_log_perf_test by 5% when using the legacy MMU.
There is no discerable improvement to the performance of the TDP MMU.
No functional change intended.
Suggested-by: Ben Gardon <bgardon@xxxxxxxxxx>
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
arch/x86/kvm/mmu.h | 3 +++
arch/x86/kvm/mmu/mmu.c | 27 +++++++++------------------
arch/x86/kvm/mmu/paging_tmpl.h | 2 ++
arch/x86/kvm/mmu/tdp_mmu.c | 10 +++++-----
4 files changed, 19 insertions(+), 23 deletions(-)
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 2c726b255fa8..8d13333f0345 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -158,6 +158,9 @@ struct kvm_page_fault {
/* Shifted addr, or result of guest page table walk if addr is a gva. */
gfn_t gfn;
+ /* The memslot containing gfn. May be NULL. */
+ struct kvm_memory_slot *slot;
+
/* Outputs of kvm_faultin_pfn. */
kvm_pfn_t pfn;
hva_t hva;
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 3352312ab1c9..fb2c95e8df00 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2890,7 +2890,7 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm,
void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
{
- struct kvm_memory_slot *slot;
+ struct kvm_memory_slot *slot = fault->slot;
kvm_pfn_t mask;
fault->huge_page_disallowed = fault->exec && fault->nx_huge_page_workaround_enabled;
@@ -2901,8 +2901,7 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
if (is_error_noslot_pfn(fault->pfn) || kvm_is_reserved_pfn(fault->pfn))
return;
- slot = gfn_to_memslot_dirty_bitmap(vcpu, fault->gfn, true);
- if (!slot)
+ if (kvm_slot_dirty_track_enabled(slot))
return;
/*
@@ -3076,13 +3075,9 @@ static bool page_fault_can_be_fast(struct kvm_page_fault *fault)
* someone else modified the SPTE from its original value.
*/
static bool
-fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
u64 *sptep, u64 old_spte, u64 new_spte)
{
- gfn_t gfn;
-
- WARN_ON(!sp->role.direct);
-
/*
* Theoretically we could also set dirty bit (and flush TLB) here in
* order to eliminate unnecessary PML logging. See comments in
@@ -3098,14 +3093,8 @@ fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
if (cmpxchg64(sptep, old_spte, new_spte) != old_spte)
return false;
- if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) {
- /*
- * The gfn of direct spte is stable since it is
- * calculated by sp->gfn.
- */
- gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
- kvm_vcpu_mark_page_dirty(vcpu, gfn);
- }
+ if (is_writable_pte(new_spte) && !is_writable_pte(old_spte))
+ mark_page_dirty_in_slot(vcpu->kvm, fault->slot, fault->gfn);
return true;
}
@@ -3233,7 +3222,7 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
* since the gfn is not stable for indirect shadow page. See
* Documentation/virt/kvm/locking.rst to get more detail.
*/
- if (fast_pf_fix_direct_spte(vcpu, sp, sptep, spte, new_spte)) {
+ if (fast_pf_fix_direct_spte(vcpu, fault, sptep, spte, new_spte)) {
ret = RET_PF_FIXED;
break;
}
@@ -3823,7 +3812,7 @@ static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
static bool kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault, int *r)
{
- struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, fault->gfn);
+ struct kvm_memory_slot *slot = fault->slot;
bool async;
/*
@@ -3888,6 +3877,8 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
int r;
fault->gfn = fault->addr >> PAGE_SHIFT;
+ fault->slot = kvm_vcpu_gfn_to_memslot(vcpu, fault->gfn);
+
if (page_fault_handle_page_track(vcpu, fault))
return RET_PF_EMULATE;
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index f70afecbf3a2..50ade6450ace 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -847,6 +847,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
}
fault->gfn = walker.gfn;
+ fault->slot = kvm_vcpu_gfn_to_memslot(vcpu, fault->gfn);
+
if (page_fault_handle_page_track(vcpu, fault)) {
shadow_page_table_clear_flood(vcpu, fault->addr);
return RET_PF_EMULATE;
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 47ec9f968406..6f733a68d750 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -533,6 +533,7 @@ static inline bool tdp_mmu_set_spte_atomic_no_dirty_log(struct kvm *kvm,
* TDP page fault.
*
* @vcpu: The vcpu instance that took the TDP page fault.
+ * @fault: The kvm_page_fault being resolved by this SPTE.
* @iter: a tdp_iter instance currently on the SPTE that should be set
* @new_spte: The value the SPTE should be set to
*
@@ -540,6 +541,7 @@ static inline bool tdp_mmu_set_spte_atomic_no_dirty_log(struct kvm *kvm,
* this function will have no side-effects.
*/
static inline bool tdp_mmu_map_set_spte_atomic(struct kvm_vcpu *vcpu,
+ struct kvm_page_fault *fault,
struct tdp_iter *iter,
u64 new_spte)
{
@@ -553,12 +555,10 @@ static inline bool tdp_mmu_map_set_spte_atomic(struct kvm_vcpu *vcpu,
* handle_changed_spte_dirty_log() to leverage vcpu->last_used_slot.
*/
if (is_writable_pte(new_spte)) {
- struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, iter->gfn);
-
- if (slot && kvm_slot_dirty_track_enabled(slot)) {
+ if (fault->slot && kvm_slot_dirty_track_enabled(fault->slot)) {
/* Enforced by kvm_mmu_hugepage_adjust. */
WARN_ON_ONCE(iter->level > PG_LEVEL_4K);
- mark_page_dirty_in_slot(kvm, slot, iter->gfn);
+ mark_page_dirty_in_slot(kvm, fault->slot, iter->gfn);
}
}
@@ -934,7 +934,7 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
if (new_spte == iter->old_spte)
ret = RET_PF_SPURIOUS;
- else if (!tdp_mmu_map_set_spte_atomic(vcpu, iter, new_spte))
+ else if (!tdp_mmu_map_set_spte_atomic(vcpu, fault, iter, new_spte))
return RET_PF_RETRY;
/*
--
2.33.0.rc1.237.g0d66db33f3-goog
