Move to/from Control Registers chapter of Intel SDM says. "Reserved bits
in CR0 remain clear after any load of those registers; attempts to set
them have no impact". Control Register chapter says "Bits 63:32 of CR0 are
reserved and must be written with zeros. Writing a nonzero value to any
of the upper 32 bits results in a general-protection exception, #GP(0)."
This patch tries to implement this twisted logic.
Signed-off-by: Gleb Natapov <g...@redhat.com>
Reported-by: Lorenzo Martignoni <martig...@gmail.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 47c6e23..1df691d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -430,12 +430,16 @@ void kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
{
cr0 |= X86_CR0_ET;
- if (cr0 & CR0_RESERVED_BITS) {
+#ifdef CONFIG_X86_64
+ if (cr0 & 0xffffffff00000000lu) {
printk(KERN_DEBUG "set_cr0: 0x%lx #GP, reserved bits 0x%lx\n",
cr0, kvm_read_cr0(vcpu));
kvm_inject_gp(vcpu, 0);
return;
}
+#endif
+
+ cr0 &= ~CR0_RESERVED_BITS;
if ((cr0 & X86_CR0_NW) && !(cr0 & X86_CR0_CD)) {
printk(KERN_DEBUG "set_cr0: #GP, CD == 0 && NW == 1\n");
--
Gleb.
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