Messages in this thread | | | Date | Sun, 30 Aug 2009 13:02:11 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 3/3] x86, AMD: Disable wrongly set X86_FEATURE_LAHF_LM CPUID bit |
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On 08/30/2009 12:30 PM, Borislav Petkov wrote: > On Sun, Aug 30, 2009 at 12:22:34PM -0700, H. Peter Anvin wrote: >> On 08/30/2009 04:50 AM, Borislav Petkov wrote: >>> clear_cpu_cap(c, X86_FEATURE_LAHF_LM); >>> + if (!rdmsrl_amd_safe(0xc001100d, &val)) { >>> + val &= ~(1ULL << 32); >>> + wrmsr_amd_safe(0xc001100d, (u32) val, >>> + (u32)(val >> 32)); >>> + } >>> + } >> We presumably want/need wrmsrl_amd_safe() here! > > Actually, it is wrmsr_amd_safe() because we need the magic value in > %edi. wrmsr_amd_safe() calls the _regs variant with the array argument. > And we don't have a wrmsrl_amd_safe-one which gets a 64bit msr value as > an argument similar to the rdmsrl one. >
That's exactly the point. We shouldn't have rdmsrl_amd_safe() on one hand and wrmsr_asm_safe() on the other. I have already fixed this up in my tree, but this kind of asymmetry should have been a big red flashing light.
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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