[v2,4/9] KVM: VMX: Truncate GPR value for DR and CR reads in !64-bit mode
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Message ID 20210422022128.3464144-5-seanjc@google.com
State New
Headers show
Series
  • KVM: x86: Fixes for (benign?) truncation bugs
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Commit Message

Sean Christopherson April 22, 2021, 2:21 a.m. UTC
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: 6aa8b732ca01 ("[PATCH] kvm: userspace interface")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/vmx/vmx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Patch
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diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 6501d66167b8..7ef4c11d655b 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5132,12 +5132,12 @@  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);
 		}
@@ -5210,7 +5210,7 @@  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));