[PATCH 0/2] kvm: disable virtualization on kdump

Chris Lalancette clalance at redhat.com
Thu Oct 30 03:35:59 EDT 2008

Eric W. Biederman wrote:
>>>> svm can writeback into memory at odd times if we don't do this, and the cost
>> is
>>>> small - clear a bit in EFER.  There's no reason to be lazy.
>>> Especially if we can clear that bit unconditionally (when
>>> EFER is present) I'm all for it.
>> That is the case.
> Cool.  I forget if we have to test for EFER on 32bit, or if we can just wrmsr
> and be done with it.  Regardless that sounds easy to do on the kexec path.

I'm pretty sure you have to test for it first; pre-64 bit x86 hardware doesn't
have the EFER register, so you'll fault on access.  On the other hand pre-64 bit
x86 hardware doesn't usually (ever?) have VT extensions either.

Chris Lalancette

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