On 4/20/2017 11:59 AM, Borislav Petkov wrote:
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@xxxxxxx>
---
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);
}
Hmmm... and actually if cpu_has(X86_FEATURE_SME) is true then it's a
given that extended_cpuid_level >= 0x8000001f. So this can be
simplified to just:
if (cpu_has(c, X86_FEATURE_SME)) {
... the rest of your suggestion (minus cpu_has()) ...
}
Thanks,
Tom
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