Re: x86: Question regarding the reset value of LINT0

[Nadav Amit <nadav.amit@gmail.com>]

Paolo Bonzini <pbonzini@redhat.com> wrote:

> 
> 
> On 09/04/2015 21:17, Bandan Das wrote:
>>> Excluding (1) all of the other issues are related to the VM BIOS. Perhaps
>>> KVM should somehow realize which VM BIOS runs? (yes, it sounds just as bad.)
>> 
>> How about renaming the toggle Avi mentioned above to something more generic
>> (KVM_DISABLE_LEGACY_QUIRKS ?) and grouping all the issues together ? Modern userspace
>> will always enable it and get the new correct behavior. When more cases are discovered,
>> KVM can just add them to the list.
> 
> It can be a VM capability (KVM_FIRMWARE_QUIRKS?) that is enabled via
> KVM_ENABLE_CAP.
> 
> The first argument in struct kvm_enable_cap can be used to add more
> quirks in the future.  For now, an argument of zero could be used to:
> 
> 1) set up LINT0 correctly
> 
> 2) set up CD and NW correctly in svm_set_cr0
> 
> AFAIK the MTRR issue in SeaBIOS was not fixed.  For that, QEMU could
> write to MSR_MTRRcap with KVM_SET_MSR.
> 
> Setting the "accessed" bit in vmx_set_segment is IMHO harmless, and we
> might as well do it even if !enable_unrestricted_guest.

Ok. I’ll send an updated version (as well as updated version of the
init/reset issues) in the next few days.

Nadav