From: Fenghua Yu fenghua.yu@intel.com
Protection Keys for Supervisor pages (PKS) enables fast, hardware thread specific, manipulation of permission restrictions on supervisor page mappings. It uses the same mechanism of Protection Keys as those on User mappings but applies that mechanism to supervisor mappings using a supervisor specific MSR.
Kernel users can thus defines 'domains' of page mappings which have an extra level of protection beyond those specified in the supervisor page table entries.
Enable PKS on supported CPUS.
Co-developed-by: Ira Weiny ira.weiny@intel.com Signed-off-by: Ira Weiny ira.weiny@intel.com Signed-off-by: Fenghua Yu fenghua.yu@intel.com
--- Changes from V2 From Thomas: Make this patch last so PKS is not enabled until all the PKS mechanisms are in place. Specifically: 1) Modify setup_pks() to call write_pkrs() to properly set up the initial value when enabled.
2) Split this patch into two. 1) a precursor patch with the required defines/config options and 2) this patch which actually enables feature on CPUs which support it.
Changes since RFC V3 Per Dave Hansen Update comment Add X86_FEATURE_PKS to disabled-features.h Rebase based on latest TIP tree --- arch/x86/include/asm/disabled-features.h | 6 +++++- arch/x86/kernel/cpu/common.c | 15 +++++++++++++++ 2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h index 164587177152..82540f0c5b6c 100644 --- a/arch/x86/include/asm/disabled-features.h +++ b/arch/x86/include/asm/disabled-features.h @@ -44,7 +44,11 @@ # define DISABLE_OSPKE (1<<(X86_FEATURE_OSPKE & 31)) #endif /* CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS */
-#define DISABLE_PKS (1<<(X86_FEATURE_PKS & 31)) +#ifdef CONFIG_ARCH_HAS_SUPERVISOR_PKEYS +# define DISABLE_PKS 0 +#else +# define DISABLE_PKS (1<<(X86_FEATURE_PKS & 31)) +#endif
#ifdef CONFIG_X86_5LEVEL # define DISABLE_LA57 0 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 35ad8480c464..f8929a557d72 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -58,6 +58,7 @@ #include <asm/intel-family.h> #include <asm/cpu_device_id.h> #include <asm/uv/uv.h> +#include <linux/pkeys.h>
#include "cpu.h"
@@ -1494,6 +1495,19 @@ static void validate_apic_and_package_id(struct cpuinfo_x86 *c) #endif }
+/* + * PKS is independent of PKU and either or both may be supported on a CPU. + * Configure PKS if the CPU supports the feature. + */ +static void setup_pks(void) +{ + if (!cpu_feature_enabled(X86_FEATURE_PKS)) + return; + + write_pkrs(INIT_PKRS_VALUE); + cr4_set_bits(X86_CR4_PKS); +} + /* * This does the hard work of actually picking apart the CPU stuff... */ @@ -1591,6 +1605,7 @@ static void identify_cpu(struct cpuinfo_x86 *c)
x86_init_rdrand(c); setup_pku(c); + setup_pks();
/* * Clear/Set all flags overridden by options, need do it