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From: Paolo Bonzini <pbonzini@redhat.com>
To: Bandan Das <bsd@redhat.com>, Nadav Amit <nadav.amit@gmail.com>
Cc: Avi Kivity <avi.kivity@gmail.com>,
	Jan Kiszka <jan.kiszka@siemens.com>,
	kvm list <kvm@vger.kernel.org>
Subject: Re: x86: Question regarding the reset value of LINT0
Date: Fri, 10 Apr 2015 11:12:17 +0200	[thread overview]
Message-ID: <552793F1.7090005@redhat.com> (raw)
In-Reply-To: <jpg7ftl2jsa.fsf@redhat.com>



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.

Paolo

  reply	other threads:[~2015-04-10  9:12 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-08 16:40 x86: Question regarding the reset value of LINT0 Nadav Amit
2015-04-08 16:44 ` Jan Kiszka
2015-04-08 16:59   ` Nadav Amit
2015-04-08 17:06     ` Jan Kiszka
2015-04-08 17:40       ` Nadav Amit
2015-04-08 17:51         ` Jan Kiszka
2015-04-08 21:49           ` Nadav Amit
2015-04-08 22:11             ` Bandan Das
2015-04-09 18:21               ` Nadav Amit
2015-04-09 18:28                 ` Avi Kivity
2015-04-09 18:49                   ` Nadav Amit
2015-04-09 19:17                     ` Bandan Das
2015-04-10  9:12                       ` Paolo Bonzini [this message]
2015-04-12 18:29                         ` Nadav Amit
2015-04-12 22:53                           ` [PATCH] KVM: x86: Support for disabling quirks Nadav Amit
2015-04-13 10:34                             ` Paolo Bonzini
2015-04-13 12:02                               ` Nadav Amit

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