KVM: extend in-kernel mmio to handle >8 byte transactions

Needed for coalesced mmio using sse.
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/x86.c

@@ -3596,20 +3596,43 @@ static void kvm_init_msr_list(void)
 static int vcpu_mmio_write(struct kvm_vcpu *vcpu, gpa_t addr, int len,
 			   const void *v)
 {
-	if (vcpu->arch.apic &&
-	    !kvm_iodevice_write(&vcpu->arch.apic->dev, addr, len, v))
-		return 0;
+	int handled = 0;
+	int n;
+
+	do {
+		n = min(len, 8);
+		if (!(vcpu->arch.apic &&
+		      !kvm_iodevice_write(&vcpu->arch.apic->dev, addr, n, v))
+		    && kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, n, v))
+			break;
+		handled += n;
+		addr += n;
+		len -= n;
+		v += n;
+	} while (len);
 
-	return kvm_io_bus_write(vcpu->kvm, KVM_MMIO_BUS, addr, len, v);
+	return handled;
 }
 
 static int vcpu_mmio_read(struct kvm_vcpu *vcpu, gpa_t addr, int len, void *v)
 {
-	if (vcpu->arch.apic &&
-	    !kvm_iodevice_read(&vcpu->arch.apic->dev, addr, len, v))
-		return 0;
+	int handled = 0;
+	int n;
+
+	do {
+		n = min(len, 8);
+		if (!(vcpu->arch.apic &&
+		      !kvm_iodevice_read(&vcpu->arch.apic->dev, addr, n, v))
+		    && kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, n, v))
+			break;
+		trace_kvm_mmio(KVM_TRACE_MMIO_READ, n, addr, *(u64 *)v);
+		handled += n;
+		addr += n;
+		len -= n;
+		v += n;
+	} while (len);
 
-	return kvm_io_bus_read(vcpu->kvm, KVM_MMIO_BUS, addr, len, v);
+	return handled;
 }
 
 static void kvm_set_segment(struct kvm_vcpu *vcpu,
@@ -3769,6 +3792,7 @@ static int emulator_read_emulated(unsigned long addr,
 				  struct kvm_vcpu *vcpu)
 {
 	gpa_t                 gpa;
+	int handled;
 
 	if (vcpu->mmio_read_completed) {
 		memcpy(val, vcpu->mmio_data, bytes);
@@ -3795,10 +3819,14 @@ static int emulator_read_emulated(unsigned long addr,
 	/*
 	 * Is this MMIO handled locally?
 	 */
-	if (!vcpu_mmio_read(vcpu, gpa, bytes, val)) {
-		trace_kvm_mmio(KVM_TRACE_MMIO_READ, bytes, gpa, *(u64 *)val);
+	handled = vcpu_mmio_read(vcpu, gpa, bytes, val);
+
+	if (handled == bytes)
 		return X86EMUL_CONTINUE;
-	}
+
+	gpa += handled;
+	bytes -= handled;
+	val += handled;
 
 	trace_kvm_mmio(KVM_TRACE_MMIO_READ_UNSATISFIED, bytes, gpa, 0);
 
@@ -3830,6 +3858,7 @@ static int emulator_write_emulated_onepage(unsigned long addr,
 					   struct kvm_vcpu *vcpu)
 {
 	gpa_t                 gpa;
+	int handled;
 
 	gpa = kvm_mmu_gva_to_gpa_write(vcpu, addr, exception);
 
@@ -3848,9 +3877,14 @@ static int emulator_write_emulated_onepage(unsigned long addr,
 	/*
 	 * Is this MMIO handled locally?
 	 */
-	if (!vcpu_mmio_write(vcpu, gpa, bytes, val))
+	handled = vcpu_mmio_write(vcpu, gpa, bytes, val);
+	if (handled == bytes)
 		return X86EMUL_CONTINUE;
 
+	gpa += handled;
+	bytes -= handled;
+	val += handled;
+
 	vcpu->mmio_needed = 1;
 	vcpu->run->exit_reason = KVM_EXIT_MMIO;
 	vcpu->run->mmio.phys_addr = vcpu->mmio_phys_addr = gpa;