From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Subject: arch/powerpc/mm/hugetlb: NestMMU workaround for hugetlb mprotect RW upgrade
NestMMU requires us to mark the pte invalid and flush the tlb when we do a
RW upgrade of pte. We fixed a variant of this in the fault path in
bd5050e38aec ("powerpc/mm/radix: Change pte relax sequence to handle nest
MMU hang").
Link: http://lkml.kernel.org/r/20190116085035.29729-6-aneesh.kumar@xxxxxxxxxxxxx
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Reviewed-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/book3s/64/hugetlb.h | 12 ++++++++
arch/powerpc/mm/hugetlbpage-hash64.c | 25 +++++++++++++++++
arch/powerpc/mm/hugetlbpage-radix.c | 17 +++++++++++
3 files changed, 54 insertions(+)
--- a/arch/powerpc/include/asm/book3s/64/hugetlb.h~arch-powerpc-mm-hugetlb-nestmmu-workaround-for-hugetlb-mprotect-rw-upgrade
+++ a/arch/powerpc/include/asm/book3s/64/hugetlb.h
@@ -13,6 +13,10 @@ radix__hugetlb_get_unmapped_area(struct
unsigned long len, unsigned long pgoff,
unsigned long flags);
+extern void radix__huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t pte);
+
static inline int hstate_get_psize(struct hstate *hstate)
{
unsigned long shift;
@@ -42,4 +46,12 @@ static inline bool gigantic_page_support
/* hugepd entry valid bit */
#define HUGEPD_VAL_BITS (0x8000000000000000UL)
+#define huge_ptep_modify_prot_start huge_ptep_modify_prot_start
+extern pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep);
+
+#define huge_ptep_modify_prot_commit huge_ptep_modify_prot_commit
+extern void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t new_pte);
#endif
--- a/arch/powerpc/mm/hugetlbpage-hash64.c~arch-powerpc-mm-hugetlb-nestmmu-workaround-for-hugetlb-mprotect-rw-upgrade
+++ a/arch/powerpc/mm/hugetlbpage-hash64.c
@@ -121,3 +121,28 @@ int __hash_page_huge(unsigned long ea, u
*ptep = __pte(new_pte & ~H_PAGE_BUSY);
return 0;
}
+
+pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep)
+{
+ unsigned long pte_val;
+ /*
+ * Clear the _PAGE_PRESENT so that no hardware parallel update is
+ * possible. Also keep the pte_present true so that we don't take
+ * wrong fault.
+ */
+ pte_val = pte_update(vma->vm_mm, addr, ptep,
+ _PAGE_PRESENT, _PAGE_INVALID, 1);
+
+ return __pte(pte_val);
+}
+
+void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr,
+ pte_t *ptep, pte_t old_pte, pte_t pte)
+{
+
+ if (radix_enabled())
+ return radix__huge_ptep_modify_prot_commit(vma, addr, ptep,
+ old_pte, pte);
+ set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
+}
--- a/arch/powerpc/mm/hugetlbpage-radix.c~arch-powerpc-mm-hugetlb-nestmmu-workaround-for-hugetlb-mprotect-rw-upgrade
+++ a/arch/powerpc/mm/hugetlbpage-radix.c
@@ -90,3 +90,20 @@ radix__hugetlb_get_unmapped_area(struct
return vm_unmapped_area(&info);
}
+
+void radix__huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
+ unsigned long addr, pte_t *ptep,
+ pte_t old_pte, pte_t pte)
+{
+ struct mm_struct *mm = vma->vm_mm;
+
+ /*
+ * To avoid NMMU hang while relaxing access we need to flush the tlb before
+ * we set the new value.
+ */
+ if (is_pte_rw_upgrade(pte_val(old_pte), pte_val(pte)) &&
+ (atomic_read(&mm->context.copros) > 0))
+ radix__flush_hugetlb_page(vma, addr);
+
+ set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
+}
_
