Messages in this thread | | | Subject | Re: [PATCH] kvm: x86: do not leak guest xcr0 into host interrupt handlers | From | Paolo Bonzini <> | Date | Thu, 7 Apr 2016 11:08:18 +0200 |
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On 05/04/2016 17:56, David Matlack wrote: > On Tue, Apr 5, 2016 at 4:28 AM, Paolo Bonzini <pbonzini@redhat.com> wrote: >> > ... >> >> While running my acceptance tests, in one case I got one CPU whose xcr0 >> had leaked into the host. This showed up as a SIGILL in strncasecmp's >> AVX code, and a simple program confirmed it: >> >> $ cat xgetbv.c >> #include <stdio.h> >> int main(void) >> { >> unsigned xcr0_h, xcr0_l; >> asm("xgetbv" : "=d"(xcr0_h), "=a"(xcr0_l) : "c"(0)); >> printf("%08x:%08x\n", xcr0_h, xcr0_l); >> } >> $ gcc xgetbv.c -O2 >> $ for i in `seq 0 55`; do echo $i `taskset -c $i ./a.out`; done|grep -v 007 >> 19 00000000:00000003 >> >> I'm going to rerun the tests without this patch, as it seems the most >> likely culprit, and leave it out of the pull request if they pass. > > Agreed this is a very likely culprit. I think I see one way the > guest's xcr0 can leak into the host.
That's cancel_injection, right? If it's just about moving the load call below, I can do that. Hmm, I will even test that today. :)
Paolo
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