[PATCH v2 8/9] KVM: vmx: handle_cr ignores 32/64-bit mode

Nadav Amit
2014-06-18T14:19:25Z

On 32-bit mode only bits [31:0] of the CR should be used for setting the CR
value. Otherwise, the host may incorrectly assume the value is invalid if bits
[63:32] are not zero. Moreover, the CR is currently being read twice when CR8
is used. Last, nested mov-cr exiting is modified to handle the CR value
correctly as well.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
---
arch/x86/kvm/vmx.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c0f53a0..cbfbb8b 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5039,7 +5039,7 @@ static int handle_cr(struct kvm_vcpu *vcpu)
reg = (exit_qualification >> 8) & 15;
switch ((exit_qualification >> 4) & 3) {
case 0: /* mov to cr */
- val = kvm_register_read(vcpu, reg);
+ val = kvm_register_readl(vcpu, reg);
trace_kvm_cr_write(cr, val);
switch (cr) {
case 0:
@@ -5056,7 +5056,7 @@ static int handle_cr(struct kvm_vcpu *vcpu)
return 1;
case 8: {
u8 cr8_prev = kvm_get_cr8(vcpu);
- u8 cr8 = kvm_register_read(vcpu, reg);
+ u8 cr8 = (u8)val;
err = kvm_set_cr8(vcpu, cr8);
kvm_complete_insn_gp(vcpu, err);
if (irqchip_in_kernel(vcpu->kvm))
@@ -6751,7 +6751,7 @@ static bool nested_vmx_exit_handled_cr(struct kvm_vcpu *vcpu,
unsigned long exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
int cr = exit_qualification & 15;
int reg = (exit_qualification >> 8) & 15;
- unsigned long val = kvm_register_read(vcpu, reg);
+ unsigned long val = kvm_register_readl(vcpu, reg);

switch ((exit_qualification >> 4) & 3) {
case 0: /* mov to cr */
--
1.9.1