Commit d8971344 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: VMX: Truncate GPR value for DR and CR reads in !64-bit mode 



Drop bits 63:32 when storing a DR/CR to a GPR when the vCPU is not in
64-bit mode.  Per the SDM:

  The operand size for these instructions is always 32 bits in non-64-bit
  modes, regardless of the operand-size attribute.

CR8 technically isn't affected as CR8 isn't accessible outside of 64-bit
mode, but fix it up for consistency and to allow for future cleanup.

Fixes: 6aa8b732 ("[PATCH] kvm: userspace interface")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210422022128.3464144-5-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0884335a

arch/x86/kvm/vmx/vmx.c

+3 −3
Original line number Diff line number Diff line
@@ -5121,12 +5121,12 @@ static int handle_cr(struct kvm_vcpu *vcpu) 
		case 3:

			WARN_ON_ONCE(enable_unrestricted_guest);

			val = kvm_read_cr3(vcpu);

			kvm_register_write(vcpu, reg, val);

			kvm_register_writel(vcpu, reg, val);

			trace_kvm_cr_read(cr, val);

			return kvm_skip_emulated_instruction(vcpu);

		case 8:

			val = kvm_get_cr8(vcpu);

			kvm_register_write(vcpu, reg, val);

			kvm_register_writel(vcpu, reg, val);

			trace_kvm_cr_read(cr, val);

			return kvm_skip_emulated_instruction(vcpu);

		}
@@ -5199,7 +5199,7 @@ static int handle_dr(struct kvm_vcpu *vcpu) 
		unsigned long val;



		kvm_get_dr(vcpu, dr, &val);

		kvm_register_write(vcpu, reg, val);

		kvm_register_writel(vcpu, reg, val);

		err = 0;

	} else {

		err = kvm_set_dr(vcpu, dr, kvm_register_readl(vcpu, reg));