Messages in this thread | | | Date | Thu, 7 Apr 2016 15:03:39 -0400 (EDT) | From | Paolo Bonzini <> | Subject | Re: [PATCH] kvm: x86: do not leak guest xcr0 into host interrupt handlers |
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----- Original Message ----- > >>> 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. :) > > Yes that's what I was thinking, move kvm_load_guest_xcr0 below that if. > > Thank you :). Let me know how testing goes.
It went well.
Paolo
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