KVM: SVM: Support string IO operations for an SEV-ES guest

For an SEV-ES guest, string-based port IO is performed to a shared
(un-encrypted) page so that both the hypervisor and guest can read or
write to it and each see the contents.

For string-based port IO operations, invoke SEV-ES specific routines that
can complete the operation using common KVM port IO support.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <9d61daf0ffda496703717218f415cdc8fd487100.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 54 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fd4c47b7c71c..536399fdbc4b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10783,6 +10783,10 @@ int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu)
 
 unsigned long kvm_get_linear_rip(struct kvm_vcpu *vcpu)
 {
+	/* Can't read the RIP when guest state is protected, just return 0 */
+	if (vcpu->arch.guest_state_protected)
+		return 0;
+
 	if (is_64_bit_mode(vcpu))
 		return kvm_rip_read(vcpu);
 	return (u32)(get_segment_base(vcpu, VCPU_SREG_CS) +
@@ -11415,6 +11419,56 @@ int kvm_sev_es_mmio_read(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned int bytes,
 }
 EXPORT_SYMBOL_GPL(kvm_sev_es_mmio_read);
 
+static int complete_sev_es_emulated_ins(struct kvm_vcpu *vcpu)
+{
+	memcpy(vcpu->arch.guest_ins_data, vcpu->arch.pio_data,
+	       vcpu->arch.pio.count * vcpu->arch.pio.size);
+	vcpu->arch.pio.count = 0;
+
+	return 1;
+}
+
+static int kvm_sev_es_outs(struct kvm_vcpu *vcpu, unsigned int size,
+			   unsigned int port, void *data,  unsigned int count)
+{
+	int ret;
+
+	ret = emulator_pio_out_emulated(vcpu->arch.emulate_ctxt, size, port,
+					data, count);
+	if (ret)
+		return ret;
+
+	vcpu->arch.pio.count = 0;
+
+	return 0;
+}
+
+static int kvm_sev_es_ins(struct kvm_vcpu *vcpu, unsigned int size,
+			  unsigned int port, void *data, unsigned int count)
+{
+	int ret;
+
+	ret = emulator_pio_in_emulated(vcpu->arch.emulate_ctxt, size, port,
+				       data, count);
+	if (ret) {
+		vcpu->arch.pio.count = 0;
+	} else {
+		vcpu->arch.guest_ins_data = data;
+		vcpu->arch.complete_userspace_io = complete_sev_es_emulated_ins;
+	}
+
+	return 0;
+}
+
+int kvm_sev_es_string_io(struct kvm_vcpu *vcpu, unsigned int size,
+			 unsigned int port, void *data,  unsigned int count,
+			 int in)
+{
+	return in ? kvm_sev_es_ins(vcpu, size, port, data, count)
+		  : kvm_sev_es_outs(vcpu, size, port, data, count);
+}
+EXPORT_SYMBOL_GPL(kvm_sev_es_string_io);
+
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);