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| author | Thomas Gleixner <tglx@linutronix.de> | 2021-06-23 14:02:07 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-06-23 18:59:44 +0200 |
| commit | 8a1dc55a3f3ef0a723c3c117a567e7b5dd2c1793 (patch) | |
| tree | 81c47aabaa457f59348e7d168325ecf9d803340c /arch/x86/kernel/cpu/common.c | |
| parent | b2681e791dbcee6acb1dca7a5076a0285109ac4c (diff) | |
| download | lwn-8a1dc55a3f3ef0a723c3c117a567e7b5dd2c1793.tar.gz lwn-8a1dc55a3f3ef0a723c3c117a567e7b5dd2c1793.zip | |
x86/cpu: Sanitize X86_FEATURE_OSPKE
X86_FEATURE_OSPKE is enabled first on the boot CPU and the feature flag is
set. Secondary CPUs have to enable CR4.PKE as well and set their per CPU
feature flag. That's ineffective because all call sites have checks for
boot_cpu_data.
Make it smarter and force the feature flag when PKU is enabled on the boot
cpu which allows then to use cpu_feature_enabled(X86_FEATURE_OSPKE) all
over the place. That either compiles the code out when PKEY support is
disabled in Kconfig or uses a static_cpu_has() for the feature check which
makes a significant difference in hotpaths, e.g. context switch.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121455.305113644@linutronix.de
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 24 |
1 files changed, 11 insertions, 13 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index f875dea49d7e..dbfb335ffac4 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -466,22 +466,20 @@ static bool pku_disabled; static __always_inline void setup_pku(struct cpuinfo_x86 *c) { - /* check the boot processor, plus compile options for PKU: */ - if (!cpu_feature_enabled(X86_FEATURE_PKU)) - return; - /* checks the actual processor's cpuid bits: */ - if (!cpu_has(c, X86_FEATURE_PKU)) - return; - if (pku_disabled) + if (c == &boot_cpu_data) { + if (pku_disabled || !cpu_feature_enabled(X86_FEATURE_PKU)) + return; + /* + * Setting CR4.PKE will cause the X86_FEATURE_OSPKE cpuid + * bit to be set. Enforce it. + */ + setup_force_cpu_cap(X86_FEATURE_OSPKE); + + } else if (!cpu_feature_enabled(X86_FEATURE_OSPKE)) { return; + } cr4_set_bits(X86_CR4_PKE); - /* - * Setting X86_CR4_PKE will cause the X86_FEATURE_OSPKE - * cpuid bit to be set. We need to ensure that we - * update that bit in this CPU's "cpu_info". - */ - set_cpu_cap(c, X86_FEATURE_OSPKE); } #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS |