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Commit eea1cff9 authored by Andre Przywara's avatar Andre Przywara Committed by Avi Kivity
Browse files

KVM: x86: fix CR8 handling 



The handling of CR8 writes in KVM is currently somewhat cumbersome.
This patch makes it look like the other CR register handlers
and fixes a possible issue in VMX, where the RIP would be incremented
despite an injected #GP.

Signed-off-by: default avatarAndre Przywara <andre.przywara@amd.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent a63512a4

arch/x86/include/asm/kvm_host.h

+1 −1
Original line number Diff line number Diff line
@@ -661,7 +661,7 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason, 
int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);

int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3);

int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);

void kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8);

int kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8);

int kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val);

int kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val);

unsigned long kvm_get_cr8(struct kvm_vcpu *vcpu);

arch/x86/kvm/svm.c

+4 −3
Original line number Diff line number Diff line
@@ -2676,16 +2676,17 @@ static int cr0_write_interception(struct vcpu_svm *svm) 
static int cr8_write_interception(struct vcpu_svm *svm)

{

	struct kvm_run *kvm_run = svm->vcpu.run;

	int r;



	u8 cr8_prev = kvm_get_cr8(&svm->vcpu);

	/* instruction emulation calls kvm_set_cr8() */

	emulate_instruction(&svm->vcpu, 0, 0, 0);

	r = emulate_instruction(&svm->vcpu, 0, 0, 0);

	if (irqchip_in_kernel(svm->vcpu.kvm)) {

		clr_cr_intercept(svm, INTERCEPT_CR8_WRITE);

		return 1;

		return r == EMULATE_DONE;

	}

	if (cr8_prev <= kvm_get_cr8(&svm->vcpu))

		return 1;

		return r == EMULATE_DONE;

	kvm_run->exit_reason = KVM_EXIT_SET_TPR;

	return 0;

}

arch/x86/kvm/vmx.c

+2 −2
Original line number Diff line number Diff line
@@ -3185,8 +3185,8 @@ static int handle_cr(struct kvm_vcpu *vcpu) 
		case 8: {

				u8 cr8_prev = kvm_get_cr8(vcpu);

				u8 cr8 = kvm_register_read(vcpu, reg);

				kvm_set_cr8(vcpu, cr8);

				skip_emulated_instruction(vcpu);

				err = kvm_set_cr8(vcpu, cr8);

				complete_insn_gp(vcpu, err);

				if (irqchip_in_kernel(vcpu->kvm))

					return 1;

				if (cr8_prev <= cr8)

arch/x86/kvm/x86.c

+8 −10
Original line number Diff line number Diff line
@@ -662,7 +662,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) 
}

EXPORT_SYMBOL_GPL(kvm_set_cr3);



int __kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)

int kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)

{

	if (cr8 & CR8_RESERVED_BITS)

		return 1;
@@ -672,12 +672,6 @@ int __kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8) 
		vcpu->arch.cr8 = cr8;

	return 0;

}



void kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)

{

	if (__kvm_set_cr8(vcpu, cr8))

		kvm_inject_gp(vcpu, 0);

}

EXPORT_SYMBOL_GPL(kvm_set_cr8);



unsigned long kvm_get_cr8(struct kvm_vcpu *vcpu)
@@ -4104,7 +4098,7 @@ static int emulator_set_cr(int cr, unsigned long val, struct kvm_vcpu *vcpu) 
		res = kvm_set_cr4(vcpu, mk_cr_64(kvm_read_cr4(vcpu), val));

		break;

	case 8:

		res = __kvm_set_cr8(vcpu, val & 0xfUL);

		res = kvm_set_cr8(vcpu, val);

		break;

	default:

		vcpu_printf(vcpu, "%s: unexpected cr %u\n", __func__, cr);
@@ -5381,8 +5375,12 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) 
	}



	/* re-sync apic's tpr */

	if (!irqchip_in_kernel(vcpu->kvm))

		kvm_set_cr8(vcpu, kvm_run->cr8);

	if (!irqchip_in_kernel(vcpu->kvm)) {

		if (kvm_set_cr8(vcpu, kvm_run->cr8) != 0) {

			r = -EINVAL;

			goto out;

		}

	}



	if (vcpu->arch.pio.count || vcpu->mmio_needed) {

		if (vcpu->mmio_needed) {