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Commit aa4d57de authored by Sean Christopherson's avatar Sean Christopherson Committed by Greg Kroah-Hartman
Browse files

KVM: SVM: Truncate GPR value for DR and CR accesses in !64-bit mode 



commit 0884335a2e653b8a045083aa1d57ce74269ac81d upstream.

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>
[sudip: manual backport to old file]
Signed-off-by: default avatarSudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9d20683f

arch/x86/kvm/svm.c

+4 −4
Original line number Diff line number Diff line
@@ -2927,7 +2927,7 @@ static int cr_interception(struct vcpu_svm *svm) 
	err = 0;

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

		cr -= 16;

		val = kvm_register_read(&svm->vcpu, reg);

		val = kvm_register_readl(&svm->vcpu, reg);

		switch (cr) {

		case 0:

			if (!check_selective_cr0_intercepted(svm, val))
@@ -2972,7 +2972,7 @@ static int cr_interception(struct vcpu_svm *svm) 
			kvm_queue_exception(&svm->vcpu, UD_VECTOR);

			return 1;

		}

		kvm_register_write(&svm->vcpu, reg, val);

		kvm_register_writel(&svm->vcpu, reg, val);

	}

	kvm_complete_insn_gp(&svm->vcpu, err);
@@ -3004,13 +3004,13 @@ static int dr_interception(struct vcpu_svm *svm) 
	if (dr >= 16) { /* mov to DRn */

		if (!kvm_require_dr(&svm->vcpu, dr - 16))

			return 1;

		val = kvm_register_read(&svm->vcpu, reg);

		val = kvm_register_readl(&svm->vcpu, reg);

		kvm_set_dr(&svm->vcpu, dr - 16, val);

	} else {

		if (!kvm_require_dr(&svm->vcpu, dr))

			return 1;

		kvm_get_dr(&svm->vcpu, dr, &val);

		kvm_register_write(&svm->vcpu, reg, val);

		kvm_register_writel(&svm->vcpu, reg, val);

	}



	skip_emulated_instruction(&svm->vcpu);