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@xxxxxxxxxx>
> ---
> 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);
>
This patch works for me. The old programs I have that use the DOS/4GW
extender (http://www.tenberry.com/) runtime no longer hanging the MS-DOS
6.22 guest when EMM386.EXE is loaded and the "set_cr0: #GP..." message
is no longer filling the logs.
:)
Now I have a different problem. dmesg is filling with
"skip_emulated_instruction: NOP" messages. As I investigate further, I
unfortunately found that RHEL 5 has a somewhat dated kvm package:
ftp://ftp.redhat.com/redhat/linux/enterprise/5Client/en/os/SRPMS/kvm-83-164.el5.src.rpm
that looks to be based on a KVM snapshot from around May of last year.
It appears to missing some recent patches in regard to
skip_emulated_instruction(). :(
Oh well. I'll try qemu without KVM hardware acceleration.
Thanks for the fast response on the LMSW patch.
Regards,
Andy
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