[RFC PATCH v4 01/26] x86/cpufeatures: Make SGX_LC feature bit depend on SGX bit

Kai Huang
2021-02-08T10:59:05Z

Move SGX_LC feature bit to CPUID dependency table to make clearing all
SGX feature bits easier. Also remove clear_sgx_caps() since it is just
a wrapper of setup_clear_cpu_cap(X86_FEATURE_SGX) now.

Suggested-by: Sean Christopherson <seanjc@google.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Kai Huang <kai.huang@intel.com>
---

Hi Jarkko, Dave,

I had your Acked-by in v3. Jarkko said this patch should be before the patch
which introduced SGX1/SGX2 bit, since it is improvement of existing code, so I
switched the order. I assumed I can still have your Acked-by because code change
was just due to patch re-ordering.

v3->v4:

- Changed patch order with the patch that introduced new SGX1/SGX2 bits, since
it is improvement of existing code, per Jarkko.
---
arch/x86/kernel/cpu/cpuid-deps.c | 1 +
arch/x86/kernel/cpu/feat_ctl.c | 12 +++---------
2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index 42af31b64c2c..d40f8e0a54ce 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -72,6 +72,7 @@ static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_AVX512_FP16, X86_FEATURE_AVX512BW },
{ X86_FEATURE_ENQCMD, X86_FEATURE_XSAVES },
{ X86_FEATURE_PER_THREAD_MBA, X86_FEATURE_MBA },
+ { X86_FEATURE_SGX_LC, X86_FEATURE_SGX },
{}
};

diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
index 3b1b01f2b248..27533a6e04fa 100644
--- a/arch/x86/kernel/cpu/feat_ctl.c
+++ b/arch/x86/kernel/cpu/feat_ctl.c
@@ -93,15 +93,9 @@ static void init_vmx_capabilities(struct cpuinfo_x86 *c)
}
#endif /* CONFIG_X86_VMX_FEATURE_NAMES */

-static void clear_sgx_caps(void)
-{
- setup_clear_cpu_cap(X86_FEATURE_SGX);
- setup_clear_cpu_cap(X86_FEATURE_SGX_LC);
-}
-
static int __init nosgx(char *str)
{
- clear_sgx_caps();
+ setup_clear_cpu_cap(X86_FEATURE_SGX);

return 0;
}
@@ -116,7 +110,7 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)

if (rdmsrl_safe(MSR_IA32_FEAT_CTL, &msr)) {
clear_cpu_cap(c, X86_FEATURE_VMX);
- clear_sgx_caps();
+ clear_cpu_cap(c, X86_FEATURE_SGX);
return;
}

@@ -177,6 +171,6 @@ void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
!(msr & FEAT_CTL_SGX_LC_ENABLED) || !enable_sgx) {
if (enable_sgx)
pr_err_once("SGX disabled by BIOS\n");
- clear_sgx_caps();
+ clear_cpu_cap(c, X86_FEATURE_SGX);
}
}
--
2.29.2