Re: [PATCH] KVM: VMX: Preserve host CR4.MCE value while in guest mode.

[Paolo Bonzini <pbonzini@redhat.com>]

On 17/04/2015 10:55, Greg KH wrote:
> On Thu, Apr 16, 2015 at 11:58:05AM -0700, Ben Serebrin wrote:
>> > The host's decision to enable machine check exceptions should remain
>> > in force during non-root mode.  KVM was writing 0 to cr4 on VCPU reset
>> > and passed a slightly-modified 0 to the vmcs.guest_cr4 value.
>> > 
>> > Tested: Built.
>> > On earlier version, tested by injecting machine check
>> > while a guest is spinning.
>> > 
>> > Before the change, if guest CR4.MCE==0, then the machine check is
>> > escalated to Catastrophic Error (CATERR) and the machine dies.
>> > If guest CR4.MCE==1, then the machine check causes VMEXIT and is
>> > handled normally by host Linux. After the change, injecting a machine
>> > check causes normal Linux machine check handling.
>> > 
>> > Signed-off-by: Ben Serebrin <serebrin@google.com>
>> > ---
>> >  arch/x86/kvm/vmx.c | 12 ++++++++++--
>> >  1 file changed, 10 insertions(+), 2 deletions(-)
> <formletter>
> 
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
> for how to do this properly.

I'll fix it up when applying to the KVM tree.

Paolo