Re: Re-enabling xsave

[John Nemeth <jnemeth%cue.bc.ca@localhost>]

On Nov 7,  9:09pm, Manuel Bouyer wrote:
} On Tue, Nov 07, 2017 at 08:06:21PM +0000, coypu%sdf.org@localhost wrote:
} > 
} > Due to XSA-52 which was a vulnerability in Xen's implementation of fpu
} > switching on AMD CPU, they made it possible to disable support for
} > XSAVE. This resulted in SIGILL for anyone using XSAVE.
} > 
} > This was Xen ~4.1. They have since fixed this issue.
} > 
} > as a stopgap measure, netbsd/xen avoids using XSAVE since, which is a
} > shame.
} > 
} > OK for reverting this stopgap measure?
} 
} Not sure if such old Xen is not still in use around ...
} It there a way to make this conditional on the hypervisor version ?

     The version of the hypervisor is detected and stored in
xen_version.  However, I'm not sure of the probe, order whether
the xen version is detected first or cpu/fpu features are detected
first.