On Wed, Feb 13, 2013 at 10:06:25AM +0200, Pekka Enberg wrote: > On Wed, Feb 13, 2013 at 2:21 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote: > >>> + rdmsrl(MSR_AMD64_BU_CFG2, value); > >>> + value &= ~(1ULL << 24); > >>> + wrmsrl(MSR_AMD64_BU_CFG2, value); > >>> + } > >>> } > >>> > >>> rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy); > >> > >> > >> However, the more serious issue is that that same kernel #GPs when > >> booted in kvm. It seems it cannot stomach that specific MSR, see the > >> second "<-- trapping instruction" below and that BU_CFG2 MSR landing in > >> %ecx in the line before that. > >> > >> Oh, and this happens only with the kvm executable (/usr/bin/kvm) in > >> debian testing. If I use qemu from git, it passes over init_amd just > >> fine. > >> > >> Hmmm.. > > > > It #GPs on an MSR, which tends to be a bug in the VMM; RDMSR/WRMSR generally > > kick out to the VMM. There isn't a huge lot of work we can do about that... > > > > I think Qemu defaults to ignoring unknown-to-it MSRs whereas maybe kvmtool > > croaks? Pekka? > > I think we should also be fine. Cyrill? Never was #gp on unknown msr register access, so I think we're safe. But maybe Borislav may give lkvm a shot just to be sure? -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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