[PATCH v3 38/41] powerpc: convert put_page() to put_user_page*()

[john.hubbard at gmail.com]

From: John Hubbard <jhubbard at nvidia.com>

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
("mm: introduce put_user_page*(), placeholder versions").

Note that this effectively changes the code's behavior in
mm_iommu_unpin(): it now ultimately calls set_page_dirty_lock(),
instead of set_page_dirty(). This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]

[1] https://lore.kernel.org/r/20190723153640.GB720@lst.de

Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Christoph Hellwig <hch at lst.de>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: linuxppc-dev at lists.ozlabs.org
Signed-off-by: John Hubbard <jhubbard at nvidia.com>
---
 arch/powerpc/kvm/book3s_64_mmu_hv.c    |  4 ++--
 arch/powerpc/kvm/book3s_64_mmu_radix.c | 19 ++++++++++++++-----
 arch/powerpc/kvm/e500_mmu.c            |  3 +--
 arch/powerpc/mm/book3s64/iommu_api.c   | 11 +++++------
 4 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 9a75f0e1933b..18646b738ce1 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -731,7 +731,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		 * we have to drop the reference on the correct tail
 		 * page to match the get inside gup()
 		 */
-		put_page(pages[0]);
+		put_user_page(pages[0]);
 	}
 	return ret;
 
@@ -1206,7 +1206,7 @@ void kvmppc_unpin_guest_page(struct kvm *kvm, void *va, unsigned long gpa,
 	unsigned long gfn;
 	int srcu_idx;
 
-	put_page(page);
+	put_user_page(page);
 
 	if (!dirty)
 		return;
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index 2d415c36a61d..f53273fbfa2d 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -821,8 +821,12 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
 	 */
 	if (!ptep) {
 		local_irq_enable();
-		if (page)
-			put_page(page);
+		if (page) {
+			if (upgrade_write)
+				put_user_page(page);
+			else
+				put_page(page);
+		}
 		return RESUME_GUEST;
 	}
 	pte = *ptep;
@@ -870,9 +874,14 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcpu,
 		*levelp = level;
 
 	if (page) {
-		if (!ret && (pte_val(pte) & _PAGE_WRITE))
-			set_page_dirty_lock(page);
-		put_page(page);
+		bool dirty = !ret && (pte_val(pte) & _PAGE_WRITE);
+		if (upgrade_write)
+			put_user_pages_dirty_lock(&page, 1, dirty);
+		else {
+			if (dirty)
+				set_page_dirty_lock(page);
+			put_page(page);
+		}
 	}
 
 	/* Increment number of large pages if we (successfully) inserted one */
diff --git a/arch/powerpc/kvm/e500_mmu.c b/arch/powerpc/kvm/e500_mmu.c
index 2d910b87e441..67bb8d59d4b1 100644
--- a/arch/powerpc/kvm/e500_mmu.c
+++ b/arch/powerpc/kvm/e500_mmu.c
@@ -850,8 +850,7 @@ int kvm_vcpu_ioctl_config_tlb(struct kvm_vcpu *vcpu,
  free_privs_first:
 	kfree(privs[0]);
  put_pages:
-	for (i = 0; i < num_pages; i++)
-		put_page(pages[i]);
+	put_user_pages(pages, num_pages);
  free_pages:
 	kfree(pages);
 	return ret;
diff --git a/arch/powerpc/mm/book3s64/iommu_api.c b/arch/powerpc/mm/book3s64/iommu_api.c
index b056cae3388b..e126193ba295 100644
--- a/arch/powerpc/mm/book3s64/iommu_api.c
+++ b/arch/powerpc/mm/book3s64/iommu_api.c
@@ -170,9 +170,8 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
 	return 0;
 
 free_exit:
-	/* free the reference taken */
-	for (i = 0; i < pinned; i++)
-		put_page(mem->hpages[i]);
+	/* free the references taken */
+	put_user_pages(mem->hpages, pinned);
 
 	vfree(mem->hpas);
 	kfree(mem);
@@ -203,6 +202,7 @@ static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
 {
 	long i;
 	struct page *page = NULL;
+	bool dirty = false;
 
 	if (!mem->hpas)
 		return;
@@ -215,10 +215,9 @@ static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
 		if (!page)
 			continue;
 
-		if (mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY)
-			SetPageDirty(page);
+		dirty = mem->hpas[i] & MM_IOMMU_TABLE_GROUP_PAGE_DIRTY;
 
-		put_page(page);
+		put_user_pages_dirty_lock(&page, 1, dirty);
 		mem->hpas[i] = 0;
 	}
 }
-- 
2.22.0