From: Ira Weiny <[email protected]> The PKRS MSR is defined as a per-logical-processor register. This isolates memory access by logical CPU. Unfortunately, the MSR is not managed by XSAVE. Therefore, tasks must save/restore the MSR value on context switch.
Define a saved PKRS value in the task struct. Initialize all tasks with the INIT_PKRS_VALUE and call pkrs_write_current() to set the MSR to the saved task value on schedule in. Co-developed-by: Fenghua Yu <[email protected]> Signed-off-by: Fenghua Yu <[email protected]> Signed-off-by: Ira Weiny <[email protected]> --- Changes for V7 Move definitions from asm/processor.h to asm/pks.h s/INIT_PKRS_VALUE/pkrs_init_value Change pks_init_task()/pks_sched_in() to functions s/pks_sched_in/pks_write_current to be used more generically later in the series --- arch/x86/include/asm/pks.h | 4 ++++ arch/x86/include/asm/processor.h | 19 ++++++++++++++++++- arch/x86/kernel/process.c | 3 +++ arch/x86/kernel/process_64.c | 3 +++ arch/x86/mm/pkeys.c | 16 ++++++++++++++++ 5 files changed, 44 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/pks.h b/arch/x86/include/asm/pks.h index 5d7067ada8fb..e7727086cec2 100644 --- a/arch/x86/include/asm/pks.h +++ b/arch/x86/include/asm/pks.h @@ -5,10 +5,14 @@ #ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS void setup_pks(void); +void pkrs_write_current(void); +void pks_init_task(struct task_struct *task); #else /* !CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */ static inline void setup_pks(void) { } +static inline void pkrs_write_current(void) { } +static inline void pks_init_task(struct task_struct *task) { } #endif /* CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */ diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index f3020c54e2cb..a6cb7d152c62 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -502,6 +502,12 @@ struct thread_struct { unsigned long cr2; unsigned long trap_nr; unsigned long error_code; + +#ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS + /* Saved Protection key register for supervisor mappings */ + u32 saved_pkrs; +#endif + #ifdef CONFIG_VM86 /* Virtual 86 mode info */ struct vm86 *vm86; @@ -768,7 +774,18 @@ static inline void spin_lock_prefetch(const void *x) #define KSTK_ESP(task) (task_pt_regs(task)->sp) #else -#define INIT_THREAD { } + +#ifdef CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS +/* + * Early task gets full permissions, the restrictive value is set in + * pks_init_task() + */ +#define INIT_THREAD { \ + .saved_pkrs = 0, \ +} +#else +#define INIT_THREAD { } +#endif extern unsigned long KSTK_ESP(struct task_struct *task); diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 1d9463e3096b..c792ac5f33a2 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -43,6 +43,7 @@ #include <asm/io_bitmap.h> #include <asm/proto.h> #include <asm/frame.h> +#include <asm/pks.h> #include "process.h" @@ -223,6 +224,8 @@ void flush_thread(void) fpu_flush_thread(); pkru_flush_thread(); + + pks_init_task(tsk); } void disable_TSC(void) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index ec0d836a13b1..8bd1f039e5bf 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -59,6 +59,7 @@ /* Not included via unistd.h */ #include <asm/unistd_32_ia32.h> #endif +#include <asm/pks.h> #include "process.h" @@ -658,6 +659,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) /* Load the Intel cache allocation PQR MSR. */ resctrl_sched_in(); + pkrs_write_current(); + return prev_p; } diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c index fbffbced81b5..eca01dc8d7ac 100644 --- a/arch/x86/mm/pkeys.c +++ b/arch/x86/mm/pkeys.c @@ -284,5 +284,21 @@ void setup_pks(void) write_pkrs(pkrs_init_value); cr4_set_bits(X86_CR4_PKS); } +; + +/* + * PKRS is only temporarily changed during specific code paths. Only a + * preemption during these windows away from the default value would + * require updating the MSR. write_pkrs() handles this optimization. + */ +void pkrs_write_current(void) +{ + write_pkrs(current->thread.saved_pkrs); +} + +void pks_init_task(struct task_struct *task) +{ + task->thread.saved_pkrs = pkrs_init_value; +} #endif /* CONFIG_ARCH_ENABLE_SUPERVISOR_PKEYS */ -- 2.28.0.rc0.12.gb6a658bd00c9
