Avi Kivity wrote: > > Hmm, looking back at the dump: > >> 1811: 8d 86 00 00 ff 3f lea 0x3fff0000(%rsi),%eax >> 1817: 83 f8 03 cmp $0x3,%eax >> 181a: 0f 87 e2 01 00 00 ja 1a02 <svm_set_msr+0x27f> > > So while gcc is using %rsi, it loads the result back into %eax, which > has the effect of dropping back into 32-bits. So looks like gcc was > right here. Sorry for spreading confusion and apologies to gcc. >
Avi, Arg. I was completely, utterly wrong about the problem here (although there is definitely still a problem). I'm sorry for making a confusing mess out of this. Here is what is actually happening: During startup, the RHEL-4 x86_64 kernel (2.6.9-67.EL, if you care) setups up the NMI watchdog. It does the following: for(i = 0; i < 4; ++i) { /* Simulator may not support it */ if (checking_wrmsrl(MSR_K7_EVNTSEL0+i, 0UL)) return; wrmsrl(MSR_K7_PERFCTR0+i, 0UL); } checking_wrmsrl() just does a "test write" to the msr; because of the code that is currently in there, this succeeds. However, when it tries to do the MSR_K7_PERFCTR0 wrmsr, *that* is where it fails, since we don't currently handle that MSR, and KVM injects a GPF into the guest (which kills it). My previous patch just happened to fix this because it was making checking_wrmsrl() fail on the EVNTSEL0, so we just returned out of this loop rather than trying to write to the PERFCTR0. Unfortunately, we can't just "fake emulate" MSR_K7_PERFCTR[0-3] like we are doing for MSR_K7_EVNTSEL[0-3]; if they are there, linux expects to be able to put values into them. I think the correct solution here is to emulate MSR_K7_PERFCTR[0-3] and MSR_K7_EVNTSEL[0-3] for real. I'm working on a patch to do this now. Chris Lalancette ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel