Re: [Xen-devel] [PATCH, fixed] linux/x86: use sysenter/syscall for 32-bit apps on 64-bit Xen

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>However, in case (2) the i386 guest kernel unconditionally goes for
>>sysenter, and the hypervisor will accept this because CPUID has advertised
>>SEP. *But* AMD CPUs do not support sysenter except in legacy mode! The
>>correct thing to do is to use syscall. The hypervisor 32-on-64 compat code
>>would accept CALLBACKTYPE_syscall, but the Linux i386 code here doesn't
>>appear to make use of it. So I would imagine that the i386 kernel running on
>>AMD hardware would cause all user processes to crash when they SYSENTER.
>
>I intentionally avoided adding syscall stuff to the 32-bit kernel, since that 
>isn't
>there in the native kernel either (as it's not really usable on native). 
>Therefore
>I'd suggest clearing SEP for pv32-on-64 guests in emulate_forced_invalid_op()

... on AMD CPUs I meant to say.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel