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 <[email protected]>
> + */
> +
> +#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 */