Re: [PATCH] KVM: Don't allow lmsw to clear cr0.pe

[Andy Walls <awalls@md.metrocast.net>]

On Wed, 2010-05-12 at 00:28 +0300, Avi Kivity wrote:
> The current lmsw implementation allows the guest to clear cr0.pe, contrary
> to the manual, which breaks EMM386.EXE.
> 
> Fix by ORing the old cr0.pe with lmsw's operand.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  arch/x86/kvm/x86.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index cd8a606..a40170c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -462,7 +462,7 @@ EXPORT_SYMBOL_GPL(kvm_set_cr0);
>  
>  void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw)
>  {
> -	kvm_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~0x0ful) | (msw & 0x0f));
> +	kvm_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~0x0eul) | (msw & 0x0f));
>  }
>  EXPORT_SYMBOL_GPL(kvm_lmsw);
>  

Cool.  I will build a kernel and test tomorrow.

Regards,
Andy