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Re: [Xen-devel] [PATCH, fixed] linux/x86: use sysenter/syscall for 32-bi
| To: | "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] [PATCH, fixed] linux/x86: use sysenter/syscall for 32-bit apps on 64-bit Xen |
| From: | "Jan Beulich" <jbeulich@xxxxxxxxxx> |
| Date: | Wed, 24 Oct 2007 15:15:41 +0100 |
| Cc: | xen-devel@xxxxxxxxxxxxxxxxxxx, Andi Kleen <ak@xxxxxxx> |
| Delivery-date: | Wed, 24 Oct 2007 07:14:40 -0700 |
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>>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 |
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