Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v3 04/11] kernel/fork: Initialize mm's PASID | Date | Sat, 05 Feb 2022 00:22:12 +0100 |
| |
On Fri, Jan 28 2022 at 12:28, Fenghua Yu wrote: > A new mm doesn't have a PASID yet when it's created. Initialize > the mm's PASID on fork() or for init_mm to INVALID_IOASID (-1).
I must be missing something here.
> diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h > index aa5f09ca5bcf..c74d1edbac2f 100644 > --- a/include/linux/sched/mm.h > +++ b/include/linux/sched/mm.h > @@ -8,6 +8,7 @@ > #include <linux/mm_types.h> > #include <linux/gfp.h> > #include <linux/sync_core.h> > +#include <linux/ioasid.h> > > /* > * Routines for handling mm_structs > @@ -433,4 +434,13 @@ static inline void membarrier_update_current_mm(struct mm_struct *next_mm) > } > #endif > > +#ifdef CONFIG_IOMMU_SVA > +static inline void mm_pasid_init(struct mm_struct *mm) > +{ > + mm->pasid = INVALID_IOASID; > +} > +#else > +static inline void mm_pasid_init(struct mm_struct *mm) {} > +#endif > + > #endif /* _LINUX_SCHED_MM_H */
So this adds mm_pasid_init() to linux/sched/mm.h which replaces:
> -static void mm_init_pasid(struct mm_struct *mm) > -{ > -#ifdef CONFIG_IOMMU_SVA > - mm->pasid = INIT_PASID; > -#endif > -} > -
I.e. already existing code which is initializing mm->pasid with INIT_PASID (0) while the replacement initializes it with INVALID_IOASID (-1).
The change log does not have any information about why INIT_PASID is the wrong initialization value and why this change is not having any side effects.
It neither mentions why having this in a global available header makes sense when the only call site is in the C file from which the already existing function is removed.
Thanks,
tglx
| |