Commit ab344828 authored Jan 21, 2010 by Gleb Natapov Committed by Marcelo Tosatti Mar 01, 2010

KVM: x86: fix checking of cr0 validity

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 <gleb@redhat.com>
Reported-by: Lorenzo Martignoni <martignlo@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

parent f0f4b930

arch/x86/kvm/x86.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -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 & 0xffffffff00000000UL) {
		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");

Admin message