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@otcwcpicx3.sc.intel.com/

Link: https://lkml.kernel.org/r/20210302103837.2562625-1-jean-philippe@linaro.org
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Cc: Jacob Pan <jacob.jun.pan@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 0974ad501a47ce5d5a8c6913287a1c31c4e44222..6613b26a88946c41afb469b894d3b66fc4712010 100644 (file)
--- a/include/linux/mm_types.h
+++ b/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;

diff --git a/kernel/fork.c b/kernel/fork.c
index d3171e8e88e5d4af93ab1fa21a2dfe4c41b67292..54cc905e5fe095d0081ec943ac2a16e487f2235b 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -994,6 +994,13 @@ static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
 #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_struct *mm, struct task_struct *p,
        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);