[RFC PATCH v4 15/16] KVM: x86/mmu: Make kvm fault handler aware of large page of private memslot

[isaku.yamahata@xxxxxxxxx]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

struct kvm_page_fault.req_level is the page level which takes care of the
faulted-in page size.  For now its calculation is only for the conventional
kvm memslot by host_pfn_mapping_level() that traverses page table.

However, host_pfn_mapping_level() cannot be used for private kvm memslot
because pages of private kvm memlost aren't mapped into user virtual
address space.  Instead page order is given when getting pfn.  Remember it
in struct kvm_page_fault and use it.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
 arch/x86/kvm/mmu/mmu.c          | 29 +++++++++++++++--------------
 arch/x86/kvm/mmu/mmu_internal.h | 12 +++++++++++-
 arch/x86/kvm/mmu/tdp_mmu.c      |  2 +-
 3 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 949ef2fa8264..bb828eb2b1e3 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3190,10 +3190,10 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn,
 
 static int __kvm_mmu_max_mapping_level(struct kvm *kvm,
 				       const struct kvm_memory_slot *slot,
-				       gfn_t gfn, int max_level, bool is_private)
+				       gfn_t gfn, int max_level, int host_level,
+				       bool is_private)
 {
 	struct kvm_lpage_info *linfo;
-	int host_level;
 
 	max_level = min(max_level, max_huge_page_level);
 	for ( ; max_level > PG_LEVEL_4K; max_level--) {
@@ -3202,24 +3202,23 @@ static int __kvm_mmu_max_mapping_level(struct kvm *kvm,
 			break;
 	}
 
-	if (is_private)
-		return max_level;
-
 	if (max_level == PG_LEVEL_4K)
 		return PG_LEVEL_4K;
 
-	host_level = host_pfn_mapping_level(kvm, gfn, slot);
+	if (!is_private) {
+		WARN_ON_ONCE(host_level != PG_LEVEL_NONE);
+		host_level = host_pfn_mapping_level(kvm, gfn, slot);
+	}
+	WARN_ON_ONCE(host_level == PG_LEVEL_NONE);
 	return min(host_level, max_level);
 }
 
 int kvm_mmu_max_mapping_level(struct kvm *kvm,
 			      const struct kvm_memory_slot *slot, gfn_t gfn,
-			      int max_level)
+			      int max_level, bool faultin_private)
 {
-	bool is_private = kvm_slot_can_be_private(slot) &&
-			  kvm_mem_is_private(kvm, gfn);
-
-	return __kvm_mmu_max_mapping_level(kvm, slot, gfn, max_level, is_private);
+	return __kvm_mmu_max_mapping_level(kvm, slot, gfn, max_level,
+					   PG_LEVEL_NONE, faultin_private);
 }
 
 void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
@@ -3244,7 +3243,8 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
 	 */
 	fault->req_level = __kvm_mmu_max_mapping_level(vcpu->kvm, slot,
 						       fault->gfn, fault->max_level,
-						       fault->is_private);
+						       fault->host_level,
+						       kvm_is_faultin_private(fault));
 	if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed)
 		return;
 
@@ -4391,6 +4391,7 @@ static int kvm_faultin_pfn_private(struct kvm_vcpu *vcpu,
 		return r;
 	}
 
+	fault->host_level = max_level;
 	fault->max_level = min(max_level, fault->max_level);
 	fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY);
 	return RET_PF_CONTINUE;
@@ -4440,7 +4441,7 @@ static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
 			return kvm_do_memory_fault_exit(vcpu, fault);
 	}
 
-	if (fault->is_private && kvm_slot_can_be_private(slot))
+	if (kvm_is_faultin_private(fault))
 		return kvm_faultin_pfn_private(vcpu, fault);
 
 	if (fault->is_private && !kvm_slot_can_be_private(fault->slot))
@@ -6922,7 +6923,7 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
 		 */
 		if (sp->role.direct &&
 		    sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn,
-							       PG_LEVEL_NUM)) {
+							       PG_LEVEL_NUM, false)) {
 			kvm_zap_one_rmap_spte(kvm, rmap_head, sptep);
 
 			if (kvm_available_flush_remote_tlbs_range())
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index bc3d38762ace..556c6ceec15f 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -359,6 +359,9 @@ struct kvm_page_fault {
 	 * is changing its own translation in the guest page tables.
 	 */
 	bool write_fault_to_shadow_pgtable;
+
+	/* valid only for private memslot && private gfn */
+	enum pg_level host_level;
 };
 
 int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
@@ -455,7 +458,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 
 int kvm_mmu_max_mapping_level(struct kvm *kvm,
 			      const struct kvm_memory_slot *slot, gfn_t gfn,
-			      int max_level);
+			      int max_level, bool faultin_private);
 void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
 void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level);
 
@@ -473,4 +476,11 @@ static inline bool kvm_hugepage_test_mixed(struct kvm_memory_slot *slot, gfn_t g
 }
 #endif
 
+static inline bool kvm_is_faultin_private(const struct kvm_page_fault *fault)
+{
+	if (IS_ENABLED(CONFIG_KVM_GENERIC_PRIVATE_MEM))
+		return fault->is_private && kvm_slot_can_be_private(fault->slot);
+	return false;
+}
+
 #endif /* __KVM_X86_MMU_INTERNAL_H */
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 612fcaac600d..6f22e38e3973 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -2176,7 +2176,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
 			continue;
 
 		max_mapping_level = kvm_mmu_max_mapping_level(kvm, slot,
-							      iter.gfn, PG_LEVEL_NUM);
+							      iter.gfn, PG_LEVEL_NUM, false);
 		if (max_mapping_level < iter.level)
 			continue;
 
-- 
2.25.1