[PATCH 2/4] KVM: x86: Add 'fault_is_private' x86 op

[Isaku Yamahata]

This callback is used by the KVM MMU to check whether a KVM page fault was
for a private GPA or not.

Originally-by: Michael Roth <michael.roth@xxxxxxx>
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
 arch/x86/include/asm/kvm-x86-ops.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  1 +
 arch/x86/kvm/mmu.h                 | 19 +++++++++++++++++++
 arch/x86/kvm/mmu/mmu_internal.h    |  2 +-
 arch/x86/kvm/x86.c                 |  8 ++++++++
 5 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index e1f57905c8fe..dc5f18ac0bd5 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -99,6 +99,7 @@ KVM_X86_OP_OPTIONAL_RET0(set_tss_addr)
 KVM_X86_OP_OPTIONAL_RET0(set_identity_map_addr)
 KVM_X86_OP_OPTIONAL_RET0(get_mt_mask)
 KVM_X86_OP(load_mmu_pgd)
+KVM_X86_OP(fault_is_private)
 KVM_X86_OP_OPTIONAL(link_private_spt)
 KVM_X86_OP_OPTIONAL(free_private_spt)
 KVM_X86_OP_OPTIONAL(split_private_spt)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 59196a80c3c8..0382d236fbf4 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1730,6 +1730,7 @@ struct kvm_x86_ops {
 
 	void (*load_mmu_pgd)(struct kvm_vcpu *vcpu, hpa_t root_hpa,
 			     int root_level);
+	bool (*fault_is_private)(struct kvm *kvm, gpa_t gpa, u64 error_code);
 
 	int (*link_private_spt)(struct kvm *kvm, gfn_t gfn, enum pg_level level,
 				void *private_spt);
diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 4aaef2132b97..1f21680b9b97 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -289,6 +289,25 @@ static inline gpa_t kvm_translate_gpa(struct kvm_vcpu *vcpu,
 	return translate_nested_gpa(vcpu, gpa, access, exception);
 }
 
+static inline bool kvm_mmu_fault_is_private_default(struct kvm *kvm, gpa_t gpa, u64 err)
+{
+	struct kvm_memory_slot *slot;
+	gfn_t gfn = gpa_to_gfn(gpa);
+
+	slot = gfn_to_memslot(kvm, gfn);
+	if (!slot)
+		return false;
+
+	if (!kvm_slot_can_be_private(slot))
+		return false;
+
+	/*
+	 * Handling below is for UPM self-tests and guests that treat userspace
+	 * as the authority on whether a fault should be private or not.
+	 */
+	return kvm_mem_is_private(kvm, gfn);
+}
+
 static inline gfn_t kvm_gfn_shared_mask(const struct kvm *kvm)
 {
 #ifdef CONFIG_KVM_MMU_PRIVATE
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index bb5709f1cb57..6b54b069d1ed 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -445,7 +445,7 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 		.max_level = vcpu->kvm->arch.tdp_max_page_level,
 		.req_level = PG_LEVEL_4K,
 		.goal_level = PG_LEVEL_4K,
-		.is_private = kvm_is_private_gpa(vcpu->kvm, cr2_or_gpa),
+		.is_private = static_call(kvm_x86_fault_is_private)(vcpu->kvm, cr2_or_gpa, err),
 	};
 	int r;
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fd14368c6bc8..0311ab450330 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9419,6 +9419,14 @@ static inline void kvm_ops_update(struct kvm_x86_init_ops *ops)
 #undef __KVM_X86_OP
 
 	kvm_pmu_ops_update(ops->pmu_ops);
+
+	/*
+	 * TODO: Once all backend fills this option, remove this and the default
+	 * function.
+	 */
+	if (!ops->runtime_ops->fault_is_private)
+		static_call_update(kvm_x86_fault_is_private,
+				   kvm_mmu_fault_is_private_default);
 }
 
 static int kvm_x86_check_processor_compatibility(void)
-- 
2.25.1




-- 
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>