On 2024-02-07 5:40 pm, Pasha Tatashin wrote:
[...]> diff --git a/drivers/iommu/iommu-pages.h
b/drivers/iommu/iommu-pages.h
new file mode 100644
index 000000000000..c412d0aaa399
--- /dev/null
+++ b/drivers/iommu/iommu-pages.h
@@ -0,0 +1,204 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2024, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
+ */
+
+#ifndef __IOMMU_PAGES_H
+#define __IOMMU_PAGES_H
+
+#include <linux/vmstat.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+
+/*
+ * All page allocation that are performed in the IOMMU subsystem must use one of
"All page allocations" is too broad; As before, this is only about
pagetable allocations, or I guess for the full nuance, allocations of
pagetables and other per-iommu_domain configuration structures which are
reasonable to report as "pagetables" to userspace.
+ * the functions below. This is necessary for the proper accounting as IOMMU
+ * state can be rather large, i.e. multiple gigabytes in size.
+ */
+
+/**
+ * __iommu_alloc_pages_node - allocate a zeroed page of a given order from
+ * specific NUMA node.
+ * @nid: memory NUMA node id
+ * @gfp: buddy allocator flags
+ * @order: page order
+ *
+ * returns the head struct page of the allocated page.
+ */
+static inline struct page *__iommu_alloc_pages_node(int nid, gfp_t gfp,
+ int order)
+{
+ struct page *page;
+
+ page = alloc_pages_node(nid, gfp | __GFP_ZERO, order);
+ if (unlikely(!page))
+ return NULL;
+
+ return page;
+}
All 3 invocations of this only use the returned struct page to trivially
derive page_address(), so we really don't need it; just clean up these
callsites a bit more.
+
+/**
+ * __iommu_alloc_pages - allocate a zeroed page of a given order.
+ * @gfp: buddy allocator flags
+ * @order: page order
+ *
+ * returns the head struct page of the allocated page.
+ */
+static inline struct page *__iommu_alloc_pages(gfp_t gfp, int order)
+{
+ struct page *page;
+
+ page = alloc_pages(gfp | __GFP_ZERO, order);
+ if (unlikely(!page))
+ return NULL;
+
+ return page;
+}
Same for the single invocation of this one.
+
+/**
+ * __iommu_alloc_page_node - allocate a zeroed page at specific NUMA node.
+ * @nid: memory NUMA node id
+ * @gfp: buddy allocator flags
+ *
+ * returns the struct page of the allocated page.
+ */
+static inline struct page *__iommu_alloc_page_node(int nid, gfp_t gfp)
+{
+ return __iommu_alloc_pages_node(nid, gfp, 0);
+}
There are no users of this at all.
+
+/**
+ * __iommu_alloc_page - allocate a zeroed page
+ * @gfp: buddy allocator flags
+ *
+ * returns the struct page of the allocated page.
+ */
+static inline struct page *__iommu_alloc_page(gfp_t gfp)
+{
+ return __iommu_alloc_pages(gfp, 0);
+}
+
+/**
+ * __iommu_free_pages - free page of a given order
+ * @page: head struct page of the page
+ * @order: page order
+ */
+static inline void __iommu_free_pages(struct page *page, int order)
+{
+ if (!page)
+ return;
+
+ __free_pages(page, order);
+}
+
+/**
+ * __iommu_free_page - free page
+ * @page: struct page of the page
+ */
+static inline void __iommu_free_page(struct page *page)
+{
+ __iommu_free_pages(page, 0);
+}
Beyond one more trivial Intel cleanup for __iommu_alloc_pages(), these 3
are then only used by tegra-smmu, so honestly I'd be inclined to just
open-code there page_address()/virt_to_page() conversions as appropriate
there (once again I think the whole thing could in fact be refactored to
not use struct pages at all because all it's ever ultimately doing with
them is page_address(), but that would be a bigger job so definitely
out-of-scope for this series).
+
+/**
+ * iommu_alloc_pages_node - allocate a zeroed page of a given order from
+ * specific NUMA node.
+ * @nid: memory NUMA node id
+ * @gfp: buddy allocator flags
+ * @order: page order
+ *
+ * returns the virtual address of the allocated page
+ */
+static inline void *iommu_alloc_pages_node(int nid, gfp_t gfp, int order)
+{
+ struct page *page = __iommu_alloc_pages_node(nid, gfp, order);
+
+ if (unlikely(!page))
+ return NULL;
As a general point I'd prefer to fold these checks into the accounting
function itself rather than repeat them all over.
+
+ return page_address(page);
+}
+
+/**
+ * iommu_alloc_pages - allocate a zeroed page of a given order
+ * @gfp: buddy allocator flags
+ * @order: page order
+ *
+ * returns the virtual address of the allocated page
+ */
+static inline void *iommu_alloc_pages(gfp_t gfp, int order)
+{
+ struct page *page = __iommu_alloc_pages(gfp, order);
+
+ if (unlikely(!page))
+ return NULL;
+
+ return page_address(page);
+}
+
+/**
+ * iommu_alloc_page_node - allocate a zeroed page at specific NUMA node.
+ * @nid: memory NUMA node id
+ * @gfp: buddy allocator flags
+ *
+ * returns the virtual address of the allocated page
+ */
+static inline void *iommu_alloc_page_node(int nid, gfp_t gfp)
+{
+ return iommu_alloc_pages_node(nid, gfp, 0);
+}
TBH I'm not entirely convinced that saving 4 characters per invocation
times 11 invocations makes this wrapper worthwhile :/
+
+/**
+ * iommu_alloc_page - allocate a zeroed page
+ * @gfp: buddy allocator flags
+ *
+ * returns the virtual address of the allocated page
+ */
+static inline void *iommu_alloc_page(gfp_t gfp)
+{
+ return iommu_alloc_pages(gfp, 0);
+}
+
+/**
+ * iommu_free_pages - free page of a given order
+ * @virt: virtual address of the page to be freed.
+ * @order: page order
+ */
+static inline void iommu_free_pages(void *virt, int order)
+{
+ if (!virt)
+ return;
+
+ __iommu_free_pages(virt_to_page(virt), order);
+}
+
+/**
+ * iommu_free_page - free page
+ * @virt: virtual address of the page to be freed.
+ */
+static inline void iommu_free_page(void *virt)
+{
+ iommu_free_pages(virt, 0);
+}
+
+/**
+ * iommu_free_pages_list - free a list of pages.
+ * @page: the head of the lru list to be freed.
+ *
+ * There are no locking requirement for these pages, as they are going to be
+ * put on a free list as soon as refcount reaches 0. Pages are put on this LRU
+ * list once they are removed from the IOMMU page tables. However, they can
+ * still be access through debugfs.
+ */
+static inline void iommu_free_pages_list(struct list_head *page)
Nit: I'd be inclined to call this iommu_put_pages_list for consistency.
+{
+ while (!list_empty(page)) {
+ struct page *p = list_entry(page->prev, struct page, lru);
+
+ list_del(&p->lru);
+ put_page(p);
+ }
+}
I realise now you've also missed the common freelist freeing sites in
iommu-dma.
Thanks,
Robin.
+
+#endif /* __IOMMU_PAGES_H */
