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[Xen-devel] xen pv and cpuid
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| Subject: | [Xen-devel] xen pv and cpuid |
| From: | Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> |
| Date: | Mon, 26 Oct 2009 10:44:51 -0700 (PDT) |
| Delivery-date: | Mon, 26 Oct 2009 10:46:30 -0700 |
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Silly x86 question
of the day:
Is it true in a PV
domain that there is no way (short of binary translation) to trap a
userland cpuid instruction into Xen?
I found the routine
pv_cpuid() in arch/x86/traps.c and assumed that userland cpuid's would find
their way into that code, but it appears to not be the case. After
adding some printks and reading the code more closely, I gather that PV OS's
somehow get their cpuid instructions replaced with an invalid op so that
kernel-land cpuid's do indeed get trapped? Then looking at the Intel SDM I
don't see any way to force cpuid at any privilege level to trap (except in an
HVM)?
(If this is all
correct, then I am sadly back to needing userland hypercalls
:-(
Thanks,
Dan
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