diff options
| author | Fenghua Yu <fenghua.yu@intel.com> | 2020-09-15 19:30:13 +0300 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-09-17 21:22:15 +0300 |
| commit | 20f0afd1fb3d7d44f4a3db5a4b6e904410862140 (patch) | |
| tree | 0a2b714214912ec3feecdd2193d0df3e51ea7851 /arch/x86/include/asm/fpu | |
| parent | 1478b99a76534b6c244cfe24fa616280a9441118 (diff) | |
| download | linux-20f0afd1fb3d7d44f4a3db5a4b6e904410862140.tar.xz | |
x86/mmu: Allocate/free a PASID
A PASID is allocated for an "mm" the first time any thread binds to an
SVA-capable device and is freed from the "mm" when the SVA is unbound
by the last thread. It's possible for the "mm" to have different PASID
values in different binding/unbinding SVA cycles.
The mm's PASID (non-zero for valid PASID or 0 for invalid PASID) is
propagated to a per-thread PASID MSR for all threads within the mm
through IPI, context switch, or inherited. This is done to ensure that a
running thread has the right PASID in the MSR matching the mm's PASID.
[ bp: s/SVM/SVA/g; massage. ]
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/1600187413-163670-10-git-send-email-fenghua.yu@intel.com
Diffstat (limited to 'arch/x86/include/asm/fpu')
| -rw-r--r-- | arch/x86/include/asm/fpu/api.h | 12 | ||||
| -rw-r--r-- | arch/x86/include/asm/fpu/internal.h | 7 |
2 files changed, 19 insertions, 0 deletions
diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h index b774c52e5411..dcd9503b1098 100644 --- a/arch/x86/include/asm/fpu/api.h +++ b/arch/x86/include/asm/fpu/api.h @@ -62,4 +62,16 @@ extern void switch_fpu_return(void); */ extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name); +/* + * Tasks that are not using SVA have mm->pasid set to zero to note that they + * will not have the valid bit set in MSR_IA32_PASID while they are running. + */ +#define PASID_DISABLED 0 + +#ifdef CONFIG_IOMMU_SUPPORT +/* Update current's PASID MSR/state by mm's PASID. */ +void update_pasid(void); +#else +static inline void update_pasid(void) { } +#endif #endif /* _ASM_X86_FPU_API_H */ diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h index 0a460f2a3f90..341d00eba3f8 100644 --- a/arch/x86/include/asm/fpu/internal.h +++ b/arch/x86/include/asm/fpu/internal.h @@ -583,6 +583,13 @@ static inline void switch_fpu_finish(struct fpu *new_fpu) pkru_val = pk->pkru; } __write_pkru(pkru_val); + + /* + * Expensive PASID MSR write will be avoided in update_pasid() because + * TIF_NEED_FPU_LOAD was set. And the PASID state won't be updated + * unless it's different from mm->pasid to reduce overhead. + */ + update_pasid(); } /* |