kvm: Add simple NMI enable/disable support

This patch adds simple NMI I/O port emulation.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

include/kvm/kvm.h

@@ -17,6 +17,8 @@ struct kvm {
 	uint64_t		ram_size;
 	void			*ram_start;
 
+	bool			nmi_disabled;
+
 	uint16_t		boot_selector;
 	uint16_t		boot_ip;
 	uint16_t		boot_sp;
@@ -33,7 +35,7 @@ void kvm__enable_singlestep(struct kvm *self);
 bool kvm__load_kernel(struct kvm *kvm, const char *kernel_filename, const char *kernel_cmdline);
 void kvm__reset_vcpu(struct kvm *self);
 void kvm__run(struct kvm *self);
-void kvm__emulate_io(struct kvm *self, uint16_t port, void *data, int direction, int size, uint32_t count);
+bool kvm__emulate_io(struct kvm *self, uint16_t port, void *data, int direction, int size, uint32_t count);
 
 /*
  * Debugging

ioport.c

@@ -1,27 +1,77 @@
 #include "kvm/kvm.h"
 
+#include <limits.h>
 #include <stdio.h>
 
-static void kvm__emulate_io_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
-{
-	fprintf(stderr, "IO error: OUT port=%x, size=%d, count=%" PRIu32 "\n", port, size, count);
+struct ioport_operations {
+	bool (*io_in)(struct kvm *self, uint16_t port, void *data, int size, uint32_t count);
+	bool (*io_out)(struct kvm *self, uint16_t port, void *data, int size, uint32_t count);
+};
 
-	kvm__show_registers(self);
-	kvm__show_code(self);
+static uint8_t ioport_to_uint8(void *data)
+{
+	uint8_t *p = data;
+
+	return *p;
 }
 
-static void kvm__emulate_io_in(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
+static bool cmos_ram_rtc_io_out(struct kvm *self, uint16_t port, void *data, int size, uint32_t count)
 {
-	fprintf(stderr, "IO error: IN port=%x, size=%d, count=%" PRIu32 "\n", port, size, count);
+	uint8_t value;
 
-	kvm__show_registers(self);
-	kvm__show_code(self);
+	value	= ioport_to_uint8(data);
+
+	self->nmi_disabled	= value & (1UL << 7);
+
+	return true;
 }
 
-void kvm__emulate_io(struct kvm *self, uint16_t port, void *data, int direction, int size, uint32_t count)
+static struct ioport_operations cmos_ram_rtc_ops = {
+	.io_out		= cmos_ram_rtc_io_out,
+};
+
+static struct ioport_operations *ioport_ops[USHRT_MAX] = {
+	[0x70]		= &cmos_ram_rtc_ops,
+};
+
+static const char *to_direction(int direction)
 {
 	if (direction == KVM_EXIT_IO_IN)
-		kvm__emulate_io_in(self, port, data, size, count);
+		return "IN";
 	else
-		kvm__emulate_io_out(self, port, data, size, count);
+		return "OUT";
+}
+
+static void ioport_error(uint16_t port, void *data, int direction, int size, uint32_t count)
+{
+	fprintf(stderr, "IO error: %s port=%x, size=%d, count=%" PRIu32 "\n", to_direction(direction), port, size, count);
+}
+
+bool kvm__emulate_io(struct kvm *self, uint16_t port, void *data, int direction, int size, uint32_t count)
+{
+	struct ioport_operations *ops = ioport_ops[port];
+	bool ret;
+
+	if (!ops)
+		goto error;
+
+	if (direction == KVM_EXIT_IO_IN) {
+		if (!ops->io_in)
+			goto error;
+
+		ret = ops->io_in(self, port, data, size, count);
+		if (!ret)
+			goto error;
+	} else {
+		if (!ops->io_out)
+			goto error;
+
+		ret = ops->io_out(self, port, data, size, count);
+		if (!ret)
+			goto error;
+	}
+	return true;
+error:
+	ioport_error(port, data, direction, size, count);
+	return false;
 }

kvm.c

@@ -473,7 +473,8 @@ void kvm__show_registers(struct kvm *self)
 	print_segment("gs ", &sregs.gs);
 	print_segment("tr ", &sregs.tr);
 	print_segment("ldt", &sregs.ldt);
-	printf(" [ efer: %016lx  apic base: %016lx ]\n", (uint64_t) sregs.efer, (uint64_t) sregs.apic_base);
+	printf(" [ efer: %016lx  apic base: %016lx  nmi: %s ]\n", (uint64_t) sregs.efer, (uint64_t) sregs.apic_base,
+		(self->nmi_disabled ? "disabled" : "enabled"));
 	printf("Interrupt bitmap:\n");
 	printf(" ");
 	for (i = 0; i < (KVM_NR_INTERRUPTS + 63) / 64; i++)

main.c

@@ -66,14 +66,20 @@ int main(int argc, char *argv[])
 			kvm__show_registers(kvm);
 			kvm__show_code(kvm);
 			break;
-		case KVM_EXIT_IO:
-			kvm__emulate_io(kvm,
+		case KVM_EXIT_IO: {
+			bool ret;
+
+			ret = kvm__emulate_io(kvm,
 					kvm->kvm_run->io.port,
 					(uint8_t *)kvm->kvm_run + kvm->kvm_run->io.data_offset,
 					kvm->kvm_run->io.direction,
 					kvm->kvm_run->io.size,
 					kvm->kvm_run->io.count);
+
+			if (!ret)
+				goto exit_kvm;
 			break;
+		}
 		default:
 			goto exit_kvm;
 		}