Add support for trapping MMIO writes to local apic registers and emulating them.

The default behavior is still to present the local apic to the guest in the
x2apic mode.

1 files changed, 71 insertions, 0 deletions

diff --git a/sys/amd64/vmm/vmm_lapic.c b/sys/amd64/vmm/vmm_lapic.c
index 13550b4..0d797e6 100644
--- a/sys/amd64/vmm/vmm_lapic.c
+++ b/sys/amd64/vmm/vmm_lapic.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 #include "vmm_ipi.h"
 #include "vmm_lapic.h"
 #include "vlapic.h"
+#include "vmm_instruction_emul.h"
 
 static int
 lapic_write(struct vlapic *vlapic, u_int offset, uint64_t val)
@@ -174,3 +175,73 @@ lapic_wrmsr(struct vm *vm, int cpu, u_int msr, uint64_t val)
 
 	return (handled);
 }
+
+int
+lapic_mmio(struct vm *vm, int cpu, u_int offset, int read,
+	   uint64_t rip, uint64_t cr3)
+{
+	int handled, error;
+	uint64_t val;
+	struct vie vie;
+	struct vlapic *vlapic;
+
+	const int UNHANDLED = 0;
+
+	vlapic = vm_lapic(vm, cpu);
+
+	vmm_fetch_instruction(vm, rip, cr3, &vie);
+
+	if (vmm_decode_instruction(&vie) != 0)
+		return (UNHANDLED);
+
+	/* Only 32-bit accesses to local apic */
+	if (vie.op_size != VIE_OP_SIZE_32BIT)
+		return (UNHANDLED);
+
+	/*
+	 * XXX
+	 * The operand register in which we store the result of the
+	 * read must be a GPR that we can modify even if the vcpu
+	 * is "running". All the GPRs qualify except for %rsp.
+	 *
+	 * This is a limitation of the vm_set_register() API
+	 * and can be fixed if necessary.
+	 */
+	if (vie.operand_register == VM_REG_GUEST_RSP)
+		return (UNHANDLED);
+
+	if (read) {
+		if ((vie.opcode_flags & VIE_F_TO_REG) == 0)
+			return (UNHANDLED);
+
+		if (vie.operand_register >= VM_REG_LAST)
+			return (UNHANDLED);
+
+		handled = lapic_read(vlapic, offset, &val);
+		if (handled) {
+			error = vm_set_register(vm, cpu, vie.operand_register,
+						val);
+			if (error)
+				panic("lapic_mmio: error %d setting gpr %d",
+				      error, vie.operand_register);
+		}
+	} else {
+		if ((vie.opcode_flags & VIE_F_FROM_REG) &&
+		    (vie.operand_register < VM_REG_LAST)) {
+			error = vm_get_register(vm, cpu, vie.operand_register,
+						&val);
+			if (error) {
+				panic("lapic_mmio: error %d getting gpr %d",
+				      error, vie.operand_register);
+			}
+		} else if (vie.opcode_flags & VIE_F_FROM_IMM) {
+			val = vie.immediate;
+		} else {
+			return (UNHANDLED);
+		}
+
+		handled = lapic_write(vlapic, offset, val);
+	}
+
+	return (handled);
+}