[PATCH v2 4/9] KVM: VMX: Truncate GPR value for DR and CR reads in !64-bit mode

Sean Christopherson
2021-04-22T02:21:45Z

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(-)

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));