KVM: PPC: Handle magic page in kvmppc_ld/st

We use kvmppc_ld and kvmppc_st to emulate load/store instructions that may as
well access the magic page. Special case it out so that we can properly access
it.

Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/include/asm/kvm_book3s.h

@@ -286,6 +286,13 @@ static inline bool is_kvmppc_resume_guest(int r)
 	return (r == RESUME_GUEST || r == RESUME_GUEST_NV);
 }
 
+static inline bool is_kvmppc_hv_enabled(struct kvm *kvm);
+static inline bool kvmppc_supports_magic_page(struct kvm_vcpu *vcpu)
+{
+	/* Only PR KVM supports the magic page */
+	return !is_kvmppc_hv_enabled(vcpu->kvm);
+}
+
 /* Magic register values loaded into r3 and r4 before the 'sc' assembly
  * instruction for the OSI hypercalls */
 #define OSI_SC_MAGIC_R3			0x113724FA

arch/powerpc/include/asm/kvm_booke.h

@@ -103,4 +103,14 @@ static inline ulong kvmppc_get_fault_dar(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.fault_dear;
 }
+
+static inline bool kvmppc_supports_magic_page(struct kvm_vcpu *vcpu)
+{
+	/* Magic page is only supported on e500v2 */
+#ifdef CONFIG_KVM_E500V2
+	return true;
+#else
+	return false;
+#endif
+}
 #endif /* __ASM_KVM_BOOKE_H__ */

arch/powerpc/kvm/powerpc.c

@@ -312,6 +312,7 @@ EXPORT_SYMBOL_GPL(kvmppc_emulate_mmio);
 int kvmppc_st(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr,
 	      bool data)
 {
+	ulong mp_pa = vcpu->arch.magic_page_pa & KVM_PAM & PAGE_MASK;
 	struct kvmppc_pte pte;
 	int r;
 
@@ -327,6 +328,16 @@ int kvmppc_st(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr,
 	if (!pte.may_write)
 		return -EPERM;
 
+	/* Magic page override */
+	if (kvmppc_supports_magic_page(vcpu) && mp_pa &&
+	    ((pte.raddr & KVM_PAM & PAGE_MASK) == mp_pa) &&
+	    !(kvmppc_get_msr(vcpu) & MSR_PR)) {
+		void *magic = vcpu->arch.shared;
+		magic += pte.eaddr & 0xfff;
+		memcpy(magic, ptr, size);
+		return EMULATE_DONE;
+	}
+
 	if (kvm_write_guest(vcpu->kvm, pte.raddr, ptr, size))
 		return EMULATE_DO_MMIO;
 
@@ -337,6 +348,7 @@ EXPORT_SYMBOL_GPL(kvmppc_st);
 int kvmppc_ld(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr,
 		      bool data)
 {
+	ulong mp_pa = vcpu->arch.magic_page_pa & KVM_PAM & PAGE_MASK;
 	struct kvmppc_pte pte;
 	int rc;
 
@@ -355,6 +367,16 @@ int kvmppc_ld(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr,
 	if (!data && !pte.may_execute)
 		return -ENOEXEC;
 
+	/* Magic page override */
+	if (kvmppc_supports_magic_page(vcpu) && mp_pa &&
+	    ((pte.raddr & KVM_PAM & PAGE_MASK) == mp_pa) &&
+	    !(kvmppc_get_msr(vcpu) & MSR_PR)) {
+		void *magic = vcpu->arch.shared;
+		magic += pte.eaddr & 0xfff;
+		memcpy(ptr, magic, size);
+		return EMULATE_DONE;
+	}
+
 	if (kvm_read_guest(vcpu->kvm, pte.raddr, ptr, size))
 		return EMULATE_DO_MMIO;