| Date | Thu, 20 Apr 2017 18:59:22 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v5 05/32] x86/CPU/AMD: Handle SME reduction in physical address size |
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On Tue, Apr 18, 2017 at 04:17:11PM -0500, Tom Lendacky wrote: > When System Memory Encryption (SME) is enabled, the physical address > space is reduced. Adjust the x86_phys_bits value to reflect this > reduction. > > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> > --- > arch/x86/kernel/cpu/amd.c | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-)
...
> @@ -622,8 +624,14 @@ static void early_init_amd(struct cpuinfo_x86 *c) > > /* Check if SME is enabled */ > rdmsrl(MSR_K8_SYSCFG, msr); > - if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT)) > + if (msr & MSR_K8_SYSCFG_MEM_ENCRYPT) { > + unsigned int ebx; > + > + ebx = cpuid_ebx(0x8000001f); > + c->x86_phys_bits -= (ebx >> 6) & 0x3f; > + } else { > clear_cpu_cap(c, X86_FEATURE_SME); > + }
Lemme do some simplifying to save an indent level, get rid of local var ebx and kill some { }-brackets for a bit better readability:
if (c->extended_cpuid_level >= 0x8000001f) { u64 msr;
if (!cpu_has(c, X86_FEATURE_SME)) return;
/* Check if SME is enabled */ rdmsrl(MSR_K8_SYSCFG, msr); if (msr & MSR_K8_SYSCFG_MEM_ENCRYPT) c->x86_phys_bits -= (cpuid_ebx(0x8000001f) >> 6) & 0x3f; else clear_cpu_cap(c, X86_FEATURE_SME); }
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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