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Date: Tue, 8 Sep 2020 21:32:04 +0800
From: Ming Mao <maoming.maoming@...wei.com>
To: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
<linux-mm@...ck.org>, <alex.williamson@...hat.com>,
<akpm@...ux-foundation.org>
CC: <cohuck@...hat.com>, <jianjay.zhou@...wei.com>,
<weidong.huang@...wei.com>, <peterx@...hat.com>,
<aarcange@...hat.com>, <wangyunjian@...wei.com>,
Ming Mao <maoming.maoming@...wei.com>
Subject: [PATCH V4 2/2] vfio: optimized for unpinning pages
The pages are unpinned one by one in unpin_user_pages_dirty_lock().
We add a new API unpin_user_hugetlb_pages_dirty_lock() which deletes
the for loop to optimize this.
If we want to unpin the hugetlb pages, all work can be done by a single
operation to the head page in this API.
Signed-off-by: Ming Mao <maoming.maoming@...wei.com>
---
drivers/vfio/vfio_iommu_type1.c | 90 +++++++++++++++++++++++++++-----
include/linux/mm.h | 3 ++
mm/gup.c | 91 +++++++++++++++++++++++++++++++++
3 files changed, 172 insertions(+), 12 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 8c1dc5136..44fc5f16c 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -609,6 +609,26 @@ static long hugetlb_page_vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr
return ret;
}
+/*
+ * put pfns for a hugetlb page
+ * @start: the PAGE_SIZE-page we start to put,can be any page in this hugetlb page
+ * @npages: the number of PAGE_SIZE-pages to put
+ * @prot: IOMMU_READ/WRITE
+ */
+static int hugetlb_put_pfn(unsigned long start, unsigned long npages, int prot)
+{
+ struct page *page;
+
+ if (!pfn_valid(start))
+ return -EFAULT;
+
+ page = pfn_to_page(start);
+ if (!page || !PageHuge(page))
+ return -EINVAL;
+
+ return unpin_user_hugetlb_pages_dirty_lock(page, npages, prot & IOMMU_WRITE);
+}
+
static long vfio_pin_hugetlb_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
long npage, unsigned long *pfn_base,
unsigned long limit)
@@ -616,7 +636,7 @@ static long vfio_pin_hugetlb_pages_remote(struct vfio_dma *dma, unsigned long va
unsigned long pfn = 0;
long ret, pinned = 0, lock_acct = 0;
dma_addr_t iova = vaddr - dma->vaddr + dma->iova;
- long pinned_loop, i;
+ long pinned_loop;
/* This code path is only user initiated */
if (!current->mm)
@@ -674,8 +694,7 @@ static long vfio_pin_hugetlb_pages_remote(struct vfio_dma *dma, unsigned long va
if (!dma->lock_cap &&
current->mm->locked_vm + lock_acct > limit) {
- for (i = 0; i < pinned_loop; i++)
- put_pfn(pfn++, dma->prot);
+ hugetlb_put_pfn(pfn, pinned_loop, dma->prot);
pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n",
__func__, limit << PAGE_SHIFT);
ret = -ENOMEM;
@@ -695,6 +714,40 @@ static long vfio_pin_hugetlb_pages_remote(struct vfio_dma *dma, unsigned long va
return pinned;
}
+static long vfio_unpin_hugetlb_pages_remote(struct vfio_dma *dma, dma_addr_t iova,
+ unsigned long pfn, long npage,
+ bool do_accounting)
+{
+ long unlocked = 0, locked = 0;
+ long i, unpinned;
+
+ for (i = 0; i < npage; i += unpinned, iova += unpinned * PAGE_SIZE) {
+ if (!is_hugetlb_page(pfn))
+ goto slow_path;
+
+ unpinned = hugetlb_put_pfn(pfn, npage - i, dma->prot);
+ if (unpinned > 0) {
+ pfn += unpinned;
+ unlocked += unpinned;
+ locked += hugetlb_page_get_externally_pinned_num(dma, pfn, unpinned);
+ } else
+ goto slow_path;
+ }
+slow_path:
+ for (; i < npage; i++, iova += PAGE_SIZE) {
+ if (put_pfn(pfn++, dma->prot)) {
+ unlocked++;
+ if (vfio_find_vpfn(dma, iova))
+ locked++;
+ }
+ }
+
+ if (do_accounting)
+ vfio_lock_acct(dma, locked - unlocked, true);
+
+ return unlocked;
+}
+
/*
* Attempt to pin pages. We really don't want to track all the pfns and
* the iommu can only map chunks of consecutive pfns anyway, so get the
@@ -993,11 +1046,18 @@ static long vfio_sync_unpin(struct vfio_dma *dma, struct vfio_domain *domain,
iommu_tlb_sync(domain->domain, iotlb_gather);
list_for_each_entry_safe(entry, next, regions, list) {
- unlocked += vfio_unpin_pages_remote(dma,
- entry->iova,
- entry->phys >> PAGE_SHIFT,
- entry->len >> PAGE_SHIFT,
- false);
+ if (is_hugetlb_page(entry->phys >> PAGE_SHIFT))
+ unlocked += vfio_unpin_hugetlb_pages_remote(dma,
+ entry->iova,
+ entry->phys >> PAGE_SHIFT,
+ entry->len >> PAGE_SHIFT,
+ false);
+ else
+ unlocked += vfio_unpin_pages_remote(dma,
+ entry->iova,
+ entry->phys >> PAGE_SHIFT,
+ entry->len >> PAGE_SHIFT,
+ false);
list_del(&entry->list);
kfree(entry);
}
@@ -1064,10 +1124,16 @@ static size_t unmap_unpin_slow(struct vfio_domain *domain,
size_t unmapped = iommu_unmap(domain->domain, *iova, len);
if (unmapped) {
- *unlocked += vfio_unpin_pages_remote(dma, *iova,
- phys >> PAGE_SHIFT,
- unmapped >> PAGE_SHIFT,
- false);
+ if (is_hugetlb_page(phys >> PAGE_SHIFT))
+ *unlocked += vfio_unpin_hugetlb_pages_remote(dma, *iova,
+ phys >> PAGE_SHIFT,
+ unmapped >> PAGE_SHIFT,
+ false);
+ else
+ *unlocked += vfio_unpin_pages_remote(dma, *iova,
+ phys >> PAGE_SHIFT,
+ unmapped >> PAGE_SHIFT,
+ false);
*iova += unmapped;
cond_resched();
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index dc7b87310..a425135d0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1202,8 +1202,11 @@ static inline void put_page(struct page *page)
#define GUP_PIN_COUNTING_BIAS (1U << 10)
void unpin_user_page(struct page *page);
+int unpin_user_hugetlb_page(struct page *page, unsigned long npages);
void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,
bool make_dirty);
+int unpin_user_hugetlb_pages_dirty_lock(struct page *pages, unsigned long npages,
+ bool make_dirty);
void unpin_user_pages(struct page **pages, unsigned long npages);
/**
diff --git a/mm/gup.c b/mm/gup.c
index 6f47697f8..14ee321eb 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -205,11 +205,42 @@ static bool __unpin_devmap_managed_user_page(struct page *page)
return true;
}
+
+static bool __unpin_devmap_managed_user_hugetlb_page(struct page *page, unsigned long npages)
+{
+ int count;
+ struct page *head = compound_head(page);
+
+ if (!page_is_devmap_managed(head))
+ return false;
+
+ hpage_pincount_sub(head, npages);
+
+ count = page_ref_sub_return(head, npages);
+
+ mod_node_page_state(page_pgdat(head), NR_FOLL_PIN_RELEASED, npages);
+ /*
+ * devmap page refcounts are 1-based, rather than 0-based: if
+ * refcount is 1, then the page is free and the refcount is
+ * stable because nobody holds a reference on the page.
+ */
+ if (count == 1)
+ free_devmap_managed_page(head);
+ else if (!count)
+ __put_page(head);
+
+ return true;
+}
#else
static bool __unpin_devmap_managed_user_page(struct page *page)
{
return false;
}
+
+static bool __unpin_devmap_managed_user_hugetlb_page(struct page *page, unsigned long npages)
+{
+ return false;
+}
#endif /* CONFIG_DEV_PAGEMAP_OPS */
/**
@@ -248,6 +279,66 @@ void unpin_user_page(struct page *page)
}
EXPORT_SYMBOL(unpin_user_page);
+int unpin_user_hugetlb_page(struct page *page, unsigned long npages)
+{
+ struct page *head;
+ long page_offset, unpinned, hugetlb_npages;
+
+ if (!page || !PageHuge(page))
+ return -EINVAL;
+
+ if (!npages)
+ return 0;
+
+ head = compound_head(page);
+ hugetlb_npages = 1UL << compound_order(head);
+ /* the offset of this subpage in the hugetlb page */
+ page_offset = page_to_pfn(page) & (hugetlb_npages - 1);
+ /* unpinned > 0, because page_offset is always less than hugetlb_npages */
+ unpinned = min_t(long, npages, (hugetlb_npages - page_offset));
+
+ if (__unpin_devmap_managed_user_hugetlb_page(page, unpinned))
+ return unpinned;
+
+ hpage_pincount_sub(head, unpinned);
+
+ if (page_ref_sub_and_test(head, unpinned))
+ __put_page(head);
+ mod_node_page_state(page_pgdat(head), NR_FOLL_PIN_RELEASED, unpinned);
+
+ return unpinned;
+}
+EXPORT_SYMBOL(unpin_user_hugetlb_page);
+
+/*
+ * @page:the first subpage to unpin in a hugetlb page
+ * @npages: number of pages to unpin
+ * @make_dirty: whether to mark the pages dirty
+ *
+ * Nearly the same as unpin_user_pages_dirty_lock
+ * If npages is 0, returns 0.
+ * If npages is >0, returns the number of
+ * pages unpinned. And this may be less than npages.
+ */
+int unpin_user_hugetlb_pages_dirty_lock(struct page *page, unsigned long npages,
+ bool make_dirty)
+{
+ struct page *head;
+
+ if (!page || !PageHuge(page))
+ return -EINVAL;
+
+ if (!npages)
+ return 0;
+
+ head = compound_head(page);
+ if (make_dirty && !PageDirty(head))
+ set_page_dirty_lock(head);
+
+ return unpin_user_hugetlb_page(page, npages);
+}
+EXPORT_SYMBOL(unpin_user_hugetlb_pages_dirty_lock);
+
/**
* unpin_user_pages_dirty_lock() - release and optionally dirty gup-pinned pages
* @pages: array of pages to be maybe marked dirty, and definitely released.
--
2.23.0
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