KVM: handle exit due to INVD in VMX

Currently the exit is unhandled, so guest halts with error if it tries
to execute INVD instruction. Call into emulator when INVD instruction
is executed by a guest instead. This instruction is not needed by ordinary
guests, but firmware (like OpenBIOS) use it and fail.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/include/asm/vmx.h

@@ -239,6 +239,7 @@ enum vmcs_field {
 #define EXIT_REASON_TASK_SWITCH         9
 #define EXIT_REASON_CPUID               10
 #define EXIT_REASON_HLT                 12
+#define EXIT_REASON_INVD                13
 #define EXIT_REASON_INVLPG              14
 #define EXIT_REASON_RDPMC               15
 #define EXIT_REASON_RDTSC               16

arch/x86/kvm/vmx.c

@@ -3349,6 +3349,11 @@ static int handle_vmx_insn(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+static int handle_invd(struct kvm_vcpu *vcpu)
+{
+	return emulate_instruction(vcpu, 0, 0, 0) == EMULATE_DONE;
+}
+
 static int handle_invlpg(struct kvm_vcpu *vcpu)
 {
 	unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
@@ -3649,6 +3654,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[EXIT_REASON_MSR_WRITE]               = handle_wrmsr,
 	[EXIT_REASON_PENDING_INTERRUPT]       = handle_interrupt_window,
 	[EXIT_REASON_HLT]                     = handle_halt,
+	[EXIT_REASON_INVD]		      = handle_invd,
 	[EXIT_REASON_INVLPG]		      = handle_invlpg,
 	[EXIT_REASON_VMCALL]                  = handle_vmcall,
 	[EXIT_REASON_VMCLEAR]	              = handle_vmx_insn,