The patch titled
Subject: powerpc/mm/iommu: allow large IOMMU page size only for hugetlb backing
has been added to the -mm tree. Its filename is
powerpc-mm-iommu-allow-large-iommu-page-size-only-for-hugetlb-backing.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/powerpc-mm-iommu-allow-large-iommu-page-size-only-for-hugetlb-backing.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/powerpc-mm-iommu-allow-large-iommu-page-size-only-for-hugetlb-backing.patch
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------------------------------------------------------
From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Subject: powerpc/mm/iommu: allow large IOMMU page size only for hugetlb backing
THP pages can get split during different code paths. An incremented
reference count does imply we will not split the compound page. But the
pmd entry can be converted to level 4 pte entries. Keep the code simpler
by allowing large IOMMU page size only if the guest ram is backed by
hugetlb pages.
Link: http://lkml.kernel.org/r/20190114095438.32470-6-aneesh.kumar@xxxxxxxxxxxxx
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Alexey Kardashevskiy <aik@xxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/mm/mmu_context_iommu.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
--- a/arch/powerpc/mm/mmu_context_iommu.c~powerpc-mm-iommu-allow-large-iommu-page-size-only-for-hugetlb-backing
+++ a/arch/powerpc/mm/mmu_context_iommu.c
@@ -98,8 +98,6 @@ static long mm_iommu_do_alloc(struct mm_
struct mm_iommu_table_group_mem_t *mem;
long i, ret = 0, locked_entries = 0;
unsigned int pageshift;
- unsigned long flags;
- unsigned long cur_ua;
mutex_lock(&mem_list_mutex);
@@ -169,22 +167,14 @@ static long mm_iommu_do_alloc(struct mm_
for (i = 0; i < entries; ++i) {
struct page *page = mem->hpages[i];
- cur_ua = ua + (i << PAGE_SHIFT);
- if (mem->pageshift > PAGE_SHIFT && PageCompound(page)) {
- pte_t *pte;
+ /*
+ * Allow to use larger than 64k IOMMU pages. Only do that
+ * if we are backed by hugetlb.
+ */
+ if ((mem->pageshift > PAGE_SHIFT) && PageHuge(page)) {
struct page *head = compound_head(page);
- unsigned int compshift = compound_order(head);
- unsigned int pteshift;
-
- local_irq_save(flags); /* disables as well */
- pte = find_linux_pte(mm->pgd, cur_ua, NULL, &pteshift);
- /* Double check it is still the same pinned page */
- if (pte && pte_page(*pte) == head &&
- pteshift == compshift + PAGE_SHIFT)
- pageshift = max_t(unsigned int, pteshift,
- PAGE_SHIFT);
- local_irq_restore(flags);
+ pageshift = compound_order(head) + PAGE_SHIFT;
}
mem->pageshift = min(mem->pageshift, pageshift);
/*
_
Patches currently in -mm which might be from aneesh.kumar@xxxxxxxxxxxxx are
mm-update-ptep_modify_prot_start-commit-to-take-vm_area_struct-as-arg.patch
mm-update-ptep_modify_prot_commit-to-take-old-pte-value-as-arg.patch
arch-powerpc-mm-nest-mmu-workaround-for-mprotect-rw-upgrade.patch
mm-hugetlb-add-prot_modify_start-commit-sequence-for-hugetlb-update.patch
arch-powerpc-mm-hugetlb-nestmmu-workaround-for-hugetlb-mprotect-rw-upgrade.patch
mm-cma-add-pf-flag-to-force-non-cma-alloc.patch
mm-update-get_user_pages_longterm-to-migrate-pages-allocated-from-cma-region.patch
powerpc-mm-iommu-allow-migration-of-cma-allocated-pages-during-mm_iommu_do_alloc.patch
powerpc-mm-iommu-allow-large-iommu-page-size-only-for-hugetlb-backing.patch
