From: Fenghua Yu <fenghua.yu@xxxxxxxxx> Subject: mm/fork: clear PASID for new mm When a new mm is created, its PASID should be cleared, i.e. the PASID is initialized to its init state 0 on both ARM and X86. This patch was part of the series introducing mm->pasid, but got lost along the way [1]. It still makes sense to have it, because each address space has a different PASID. And the IOMMU code in iommu_sva_alloc_pasid() expects the pasid field of a new mm struct to be cleared. [1] https://lore.kernel.org/linux-iommu/YDgh53AcQHT+T3L0@xxxxxxxxxxxxxxxxxxxxxxx/ Link: https://lkml.kernel.org/r/20210302103837.2562625-1-jean-philippe@xxxxxxxxxx Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx> Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> Reviewed-by: Tony Luck <tony.luck@xxxxxxxxx> Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mm_types.h | 1 + kernel/fork.c | 8 ++++++++ 2 files changed, 9 insertions(+) --- a/include/linux/mm_types.h~mm-fork-clear-pasid-for-new-mm +++ a/include/linux/mm_types.h @@ -23,6 +23,7 @@ #endif #define AT_VECTOR_SIZE (2*(AT_VECTOR_SIZE_ARCH + AT_VECTOR_SIZE_BASE + 1)) +#define INIT_PASID 0 struct address_space; struct mem_cgroup; --- a/kernel/fork.c~mm-fork-clear-pasid-for-new-mm +++ a/kernel/fork.c @@ -994,6 +994,13 @@ static void mm_init_owner(struct mm_stru #endif } +static void mm_init_pasid(struct mm_struct *mm) +{ +#ifdef CONFIG_IOMMU_SUPPORT + mm->pasid = INIT_PASID; +#endif +} + static void mm_init_uprobes_state(struct mm_struct *mm) { #ifdef CONFIG_UPROBES @@ -1024,6 +1031,7 @@ static struct mm_struct *mm_init(struct mm_init_cpumask(mm); mm_init_aio(mm); mm_init_owner(mm, p); + mm_init_pasid(mm); RCU_INIT_POINTER(mm->exe_file, NULL); mmu_notifier_subscriptions_init(mm); init_tlb_flush_pending(mm); _
