Re: [PATCH v24 07/24] x86/cpu/intel: Detect SGX supprt

[Borislav Petkov]

On Sat, Nov 30, 2019 at 01:13:09AM +0200, Jarkko Sakkinen wrote:

Typo in the subject:

Subject: Re: [PATCH v24 07/24] x86/cpu/intel: Detect SGX supprt
							 ^^^^^^
> From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> 
> When the CPU supports SGX, check that the BIOS has enabled SGX and SGX1
> opcodes are available. Otherwise, all the SGX related capabilities.
> 
> In addition, clear X86_FEATURE_SGX_LC also in the case when the launch
> enclave are read-only. This way the feature bit reflects the level that
> Linux supports the launch control.
> 
> The check is done for every CPU, not just BSP, in order to verify that
> MSR_IA32_FEATURE_CONTROL is correctly configured on all CPUs. The other
> parts of the kernel, like the enclave driver, expect the same
> configuration from all CPUs.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Co-developed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
> ---
>  arch/x86/kernel/cpu/intel.c | 41 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)

...

> @@ -761,6 +797,11 @@ static void init_intel(struct cpuinfo_x86 *c)
>  	if (cpu_has(c, X86_FEATURE_TME))
>  		detect_tme(c);
>  
> +#ifdef CONFIG_INTEL_SGX
> +	if (cpu_has(c, X86_FEATURE_SGX))
> +		detect_sgx(c);
> +#endif

You can remove the ifdeffery here and put the ifdef around the function
body and drop the __maybe_unused tag:

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index ef41431b3f70..2f3414eff99d 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -624,8 +624,9 @@ static void detect_tme(struct cpuinfo_x86 *c)
 	c->x86_phys_bits -= keyid_bits;
 }
 
-static void __maybe_unused detect_sgx(struct cpuinfo_x86 *c)
+static void detect_sgx(struct cpuinfo_x86 *c)
 {
+#ifdef CONFIG_INTEL_SGX
 	unsigned long long fc;
 
 	rdmsrl(MSR_IA32_FEATURE_CONTROL, fc);
@@ -658,6 +659,7 @@ static void __maybe_unused detect_sgx(struct cpuinfo_x86 *c)
 
 err_msrs_rdonly:
 	setup_clear_cpu_cap(X86_FEATURE_SGX_LC);
+#endif
 }
 
 static void init_cpuid_fault(struct cpuinfo_x86 *c)
@@ -797,10 +799,8 @@ static void init_intel(struct cpuinfo_x86 *c)
 	if (cpu_has(c, X86_FEATURE_TME))
 		detect_tme(c);
 
-#ifdef CONFIG_INTEL_SGX
 	if (cpu_has(c, X86_FEATURE_SGX))
 		detect_sgx(c);
-#endif
 
 	init_intel_misc_features(c);
 

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette