[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [Patch 2/4] Refining Xsave/Xrestore support
In my patch, if processor supports CR4.OSXSAVE, Xen will enable it and won't clear it as long as we are in ROOT mode. Shan Haitao 2010/10/28 Jan Beulich <JBeulich@xxxxxxxxxx>: >>>> On 28.10.10 at 04:57, Haitao Shan <maillists.shan@xxxxxxxxx> wrote: >> My approach is based an old PV-OPS kernel source. Kernel tries to set >> CR4.OSXSAVE and read it back to determine whether Xsave is actually >> available. > > Hmm, in our kernels we check the OSXSAVE feature bit instead, > expecting (just like for FXSAVE) the hypervisor to enable the bit > in CR4 when it supports the feature. > > I think a mechanism needs to be found in the hypervisor that > accommodates both current pv-ops and current forward port > kernels' behaviors. > > Jan > >> 2010/10/28 Jeremy Fitzhardinge <jeremy@xxxxxxxx>: >>> On 10/27/2010 12:04 AM, Haitao Shan wrote: >>>> Hi, Keir, >>>> >>>> This is patch #2, which adds PV guest Xsave support. >>> >>> How does a PV guest know whether Xsave support is available? Previous >>> versions of Xen left the xsave cpu feature flag set even though xsave >>> wasn't usable by the domain, so I had to forceably mask it from the >>> cpuid features within the domain. Given that a PV domain can't rely on >>> X86_FEATURE_XSAVE, how can it tell that the feature is actually usable? >>> >>> Thanks, >>> J >>> >> >> _______________________________________________ >> Xen-devel mailing list >> Xen-devel@xxxxxxxxxxxxxxxxxxx >> http://lists.xensource.com/xen-devel > > > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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