Commit 0884335a authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: SVM: Truncate GPR value for DR and CR accesses in !64-bit mode 



Drop bits 63:32 on loads/stores to/from DRs and CRs when the vCPU is not
in 64-bit mode.  The APM states bits 63:32 are dropped for both DRs and
CRs:

  In 64-bit mode, the operand size is fixed at 64 bits without the need
  for a REX prefix. In non-64-bit mode, the operand size is fixed at 32
  bits and the upper 32 bits of the destination are forced to 0.

Fixes: 7ff76d58 ("KVM: SVM: enhance MOV CR intercept handler")
Fixes: cae3797a ("KVM: SVM: enhance mov DR intercept handler")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210422022128.3464144-4-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 886bbcc7

arch/x86/kvm/svm/svm.c

+4 −4
Original line number Diff line number Diff line
@@ -2451,7 +2451,7 @@ static int cr_interception(struct kvm_vcpu *vcpu) 
	err = 0;

	if (cr >= 16) { /* mov to cr */

		cr -= 16;

		val = kvm_register_read(vcpu, reg);

		val = kvm_register_readl(vcpu, reg);

		trace_kvm_cr_write(cr, val);

		switch (cr) {

		case 0:
@@ -2497,7 +2497,7 @@ static int cr_interception(struct kvm_vcpu *vcpu) 
			kvm_queue_exception(vcpu, UD_VECTOR);

			return 1;

		}

		kvm_register_write(vcpu, reg, val);

		kvm_register_writel(vcpu, reg, val);

		trace_kvm_cr_read(cr, val);

	}

	return kvm_complete_insn_gp(vcpu, err);
@@ -2563,11 +2563,11 @@ static int dr_interception(struct kvm_vcpu *vcpu) 
	dr = svm->vmcb->control.exit_code - SVM_EXIT_READ_DR0;

	if (dr >= 16) { /* mov to DRn  */

		dr -= 16;

		val = kvm_register_read(vcpu, reg);

		val = kvm_register_readl(vcpu, reg);

		err = kvm_set_dr(vcpu, dr, val);

	} else {

		kvm_get_dr(vcpu, dr, &val);

		kvm_register_write(vcpu, reg, val);

		kvm_register_writel(vcpu, reg, val);

	}



	return kvm_complete_insn_gp(vcpu, err);