Messages in this thread | | | Date | Tue, 12 Feb 2013 16:21:13 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [tip:x86/cpu] x86, AMD: Enable WC+ memory type on family 10 processors |
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On 02/12/2013 04:16 PM, Borislav Petkov wrote: > > This family check is redundant, we're already in a 0x10 if-branch > above. Boris had sent a second version which doesn't have that check: > http://marc.info/?l=linux-kernel&m=135949774114910 but I don't know how this > other version has gotten in. > > @hpa: maybe replace - patch is still at the top of tip:x86/cpu? >
I'll check with Ingo if that is doable.
>> + 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?
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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