Re: [PATCH 2/3] kvm: svm: reset cr0 properly on vcpu reset

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On 17.03.2010, at 22:42, Eduardo Habkost wrote:

> On Wed, Mar 17, 2010 at 07:17:32PM +0100, Alexander Graf wrote:
>> Eduardo Habkost wrote:
>>> svm_vcpu_reset() was not properly resetting the contents of the guest-visible
>>> cr0 register, causing the following issue:
>>> https://bugzilla.redhat.com/show_bug.cgi?id=525699
>>> 
>>> Without resetting cr0 properly, the vcpu was running the SIPI bootstrap routine
>>> with paging enabled, making the vcpu get a pagefault exception while trying to
>>> run it.
>>> 
>>> Instead of setting vmcb->save.cr0 directly, the new code just resets
>>> kvm->arch.cr0 and calls kvm_set_cr0(). The bits that were set/cleared on
>>> vmcb->save.cr0 (PG, WP, !CD, !NW) will be set properly by svm_set_cr0().
>>> 
>>> kvm_set_cr0() is used instead of calling svm_set_cr0() directly to make sure
>>> kvm_mmu_reset_context() is called to reset the mmu to nonpaging mode.
>>> 
>>> Signed-off-by: Eduardo Habkost <ehabkost@xxxxxxxxxx>
>>> 
>> 
>> Should this go into -stable?
> 
> I think so. The patch is from October, was -stable branched before that?

If I read the diff log correctly 2.6.32 kvm development was branched off end of July 2009. The important question is if this patch fixes a regression introduced by some speedup magic.


Alex--
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