@@ -2824,11 +2824,19 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep)
static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn,
const struct kvm_memory_slot *slot)
{
- struct page *page = pfn_to_page(pfn);
unsigned long hva;
+ struct page *page;
pte_t *pte;
int level;
+ /*
+ * Note, @slot must be non-NULL, i.e. the caller is responsible for
+ * ensuring @pfn isn't garbage and is backed by a memslot.
+ */
+ page = kvm_pfn_to_refcounted_page(pfn);
+ if (!page)
+ return PG_LEVEL_4K;
+
if (!PageCompound(page) && !kvm_is_zone_device_page(page))
return PG_LEVEL_4K;
@@ -2880,7 +2888,7 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
if (unlikely(fault->max_level == PG_LEVEL_4K))
return;
- if (is_error_noslot_pfn(fault->pfn) || !kvm_pfn_to_refcounted_page(fault->pfn))
+ if (is_error_noslot_pfn(fault->pfn))
return;
if (kvm_slot_dirty_track_enabled(slot))
@@ -5950,7 +5958,7 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
* the guest, and the guest page table is using 4K page size
* mapping if the indirect sp has level = 1.
*/
- if (sp->role.direct && kvm_pfn_to_refcounted_page(pfn) &&
+ if (sp->role.direct &&
sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn,
pfn, PG_LEVEL_NUM)) {
pte_list_remove(kvm, rmap_head, sptep);
@@ -1737,8 +1737,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
continue;
pfn = spte_to_pfn(iter.old_spte);
- if (!kvm_pfn_to_refcounted_page(pfn) ||
- iter.level >= kvm_mmu_max_mapping_level(kvm, slot, iter.gfn,
+ if (iter.level >= kvm_mmu_max_mapping_level(kvm, slot, iter.gfn,
pfn, PG_LEVEL_NUM))
continue;
Move the check that restricts mapping huge pages into the guest to pfns that are backed by refcounted 'struct page' memory into the helper that actually "requires" a 'struct page', host_pfn_mapping_level(). In addition to deduplicating code, moving the check to the helper eliminates the subtle requirement that the caller check that the incoming pfn is backed by a refcounted struct page, and as an added bonus avoids an extra pfn_to_page() lookup. Note, the is_error_noslot_pfn() check in kvm_mmu_hugepage_adjust() needs to stay where it is, as it guards against dereferencing a NULL memslot in the kvm_slot_dirty_track_enabled() that follows. No functional change intended. Signed-off-by: Sean Christopherson <seanjc@google.com> --- arch/x86/kvm/mmu/mmu.c | 14 +++++++++++--- arch/x86/kvm/mmu/tdp_mmu.c | 3 +-- 2 files changed, 12 insertions(+), 5 deletions(-)