Messages in this thread | | | Date | Thu, 17 Sep 2015 16:32:53 +0100 | From | Andrew Cooper <> | Subject | Re: [Xen-devel] [PATCH 0/3] x86/paravirt: Fix baremetal paravirt MSR ops |
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On 17/09/15 16:27, Borislav Petkov wrote: > On Thu, Sep 17, 2015 at 01:39:26PM +0200, Paolo Bonzini wrote: >> That's not a big deal, that's what *_safe is for. The problem is that >> there are definitely some cases where the *_safe version is not being used. > I mean to do feature checks which assure you that those MSRs are > there so you don't need the safe variants. And that is not always > easy/possible. >
There are plenty of non-architectural MSRs in use which don't have feature bits.
Xen used to have problems booting when using the masking MSRs when booting virtualised. Nowadays it uses a cpu vendor check and _safe() probe to detect support.
~Andrew
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