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Message-ID: <2553f102-de17-b23b-4cd8-fefaf2a04f24@huawei.com>
Date: Tue, 10 Nov 2020 21:42:33 +0800
From: "xuxiaoyang (C)" <xuxiaoyang2@...wei.com>
To: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
<alex.williamson@...hat.com>
CC: <kwankhede@...dia.com>, <wu.wubin@...wei.com>,
<maoming.maoming@...wei.com>, <xieyingtai@...wei.com>,
<lizhengui@...wei.com>, <wubinfeng@...wei.com>,
<xuxiaoyang2@...wei.com>
Subject: [PATCH] vfio iommu type1: Improve vfio_iommu_type1_pin_pages
performance
vfio_iommu_type1_pin_pages is very inefficient because
it is processed page by page when calling vfio_pin_page_external.
Added contiguous_vaddr_get_pfn to process continuous pages
to reduce the number of loops, thereby improving performance.
Signed-off-by: Xiaoyang Xu <xuxiaoyang2@...wei.com>
---
drivers/vfio/vfio_iommu_type1.c | 241 ++++++++++++++++++++++++++++----
1 file changed, 214 insertions(+), 27 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 67e827638995..935f80807527 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -628,6 +628,206 @@ static int vfio_unpin_page_external(struct vfio_dma *dma, dma_addr_t iova,
return unlocked;
}
+static int contiguous_vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
+ int prot, long npage, unsigned long *phys_pfn)
+{
+ struct page **pages = NULL;
+ unsigned int flags = 0;
+ int i, ret;
+
+ pages = kvmalloc_array(npage, sizeof(struct page *), GFP_KERNEL);
+ if (!pages)
+ return -ENOMEM;
+
+ if (prot & IOMMU_WRITE)
+ flags |= FOLL_WRITE;
+
+ mmap_read_lock(mm);
+ ret = pin_user_pages_remote(mm, vaddr, npage, flags | FOLL_LONGTERM,
+ pages, NULL, NULL);
+ mmap_read_unlock(mm);
+
+ for (i = 0; i < ret; i++)
+ *(phys_pfn + i) = page_to_pfn(pages[i]);
+
+ kvfree(pages);
+
+ return ret;
+}
+
+static int vfio_pin_contiguous_pages_external(struct vfio_iommu *iommu,
+ struct vfio_dma *dma,
+ unsigned long *user_pfn,
+ int npage, unsigned long *phys_pfn,
+ bool do_accounting)
+{
+ int ret, i, j, lock_acct = 0;
+ unsigned long remote_vaddr;
+ dma_addr_t iova;
+ struct mm_struct *mm;
+ struct vfio_pfn *vpfn;
+
+ mm = get_task_mm(dma->task);
+ if (!mm)
+ return -ENODEV;
+
+ iova = user_pfn[0] << PAGE_SHIFT;
+ remote_vaddr = dma->vaddr + iova - dma->iova;
+ ret = contiguous_vaddr_get_pfn(mm, remote_vaddr, dma->prot,
+ npage, phys_pfn);
+ mmput(mm);
+ if (ret <= 0)
+ return ret;
+
+ npage = ret;
+ for (i = 0; i < npage; i++) {
+ iova = user_pfn[i] << PAGE_SHIFT;
+ ret = vfio_add_to_pfn_list(dma, iova, phys_pfn[i]);
+ if (ret)
+ goto unwind;
+
+ if (!is_invalid_reserved_pfn(phys_pfn[i]))
+ lock_acct++;
+
+ if (iommu->dirty_page_tracking) {
+ unsigned long pgshift = __ffs(iommu->pgsize_bitmap);
+
+ /*
+ * Bitmap populated with the smallest supported page
+ * size
+ */
+ bitmap_set(dma->bitmap,
+ (iova - dma->iova) >> pgshift, 1);
+ }
+ }
+
+ if (do_accounting) {
+ ret = vfio_lock_acct(dma, lock_acct, true);
+ if (ret) {
+ if (ret == -ENOMEM)
+ pr_warn("%s: Task %s (%d) RLIMIT_MEMLOCK (%ld) exceeded\n",
+ __func__, dma->task->comm, task_pid_nr(dma->task),
+ task_rlimit(dma->task, RLIMIT_MEMLOCK));
+ goto unwind;
+ }
+ }
+
+ return i;
+unwind:
+ for (j = 0; j < npage; j++) {
+ put_pfn(phys_pfn[j], dma->prot);
+ phys_pfn[j] = 0;
+ }
+
+ for (j = 0; j < i; j++) {
+ iova = user_pfn[j] << PAGE_SHIFT;
+ vpfn = vfio_find_vpfn(dma, iova);
+ if (vpfn)
+ vfio_remove_from_pfn_list(dma, vpfn);
+ }
+
+ return ret;
+}
+
+static int vfio_iommu_type1_pin_contiguous_pages(struct vfio_iommu *iommu,
+ struct vfio_dma *dma,
+ unsigned long *user_pfn,
+ int npage, unsigned long *phys_pfn,
+ bool do_accounting)
+{
+ int ret, i, j;
+ unsigned long remote_vaddr;
+ dma_addr_t iova;
+
+ ret = vfio_pin_contiguous_pages_external(iommu, dma, user_pfn, npage,
+ phys_pfn, do_accounting);
+ if (ret == npage)
+ return ret;
+
+ if (ret < 0)
+ ret = 0;
+
+ for (i = ret; i < npage; i++) {
+ iova = user_pfn[i] << PAGE_SHIFT;
+ remote_vaddr = dma->vaddr + iova - dma->iova;
+
+ ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn[i],
+ do_accounting);
+ if (ret)
+ goto pin_unwind;
+
+ ret = vfio_add_to_pfn_list(dma, iova, phys_pfn[i]);
+ if (ret) {
+ if (put_pfn(phys_pfn[i], dma->prot) && do_accounting)
+ vfio_lock_acct(dma, -1, true);
+ goto pin_unwind;
+ }
+
+ if (iommu->dirty_page_tracking) {
+ unsigned long pgshift = __ffs(iommu->pgsize_bitmap);
+
+ /*
+ * Bitmap populated with the smallest supported page
+ * size
+ */
+ bitmap_set(dma->bitmap,
+ (iova - dma->iova) >> pgshift, 1);
+ }
+ }
+
+ return i;
+
+pin_unwind:
+ phys_pfn[i] = 0;
+ for (j = 0; j < i; j++) {
+ dma_addr_t iova;
+
+ iova = user_pfn[j] << PAGE_SHIFT;
+ vfio_unpin_page_external(dma, iova, do_accounting);
+ phys_pfn[j] = 0;
+ }
+
+ return ret;
+}
+
+static int vfio_iommu_type1_get_contiguous_pages_length(struct vfio_iommu *iommu,
+ unsigned long *user_pfn, int npage, int prot)
+{
+ struct vfio_dma *dma_base;
+ int i;
+ dma_addr_t iova;
+ struct vfio_pfn *vpfn;
+
+ if (npage <= 1)
+ return npage;
+
+ iova = user_pfn[0] << PAGE_SHIFT;
+ dma_base = vfio_find_dma(iommu, iova, PAGE_SIZE);
+ if (!dma_base)
+ return -EINVAL;
+
+ if ((dma_base->prot & prot) != prot)
+ return -EPERM;
+
+ for (i = 1; i < npage; i++) {
+ iova = user_pfn[i] << PAGE_SHIFT;
+
+ if (iova >= dma_base->iova + dma_base->size ||
+ iova + PAGE_SIZE <= dma_base->iova)
+ break;
+
+ vpfn = vfio_iova_get_vfio_pfn(dma_base, iova);
+ if (vpfn) {
+ vfio_iova_put_vfio_pfn(dma_base, vpfn);
+ break;
+ }
+
+ if (user_pfn[i] != user_pfn[0] + i)
+ break;
+ }
+ return i;
+}
+
static int vfio_iommu_type1_pin_pages(void *iommu_data,
struct iommu_group *iommu_group,
unsigned long *user_pfn,
@@ -637,9 +837,9 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
struct vfio_iommu *iommu = iommu_data;
struct vfio_group *group;
int i, j, ret;
- unsigned long remote_vaddr;
struct vfio_dma *dma;
bool do_accounting;
+ int contiguous_npage;
if (!iommu || !user_pfn || !phys_pfn)
return -EINVAL;
@@ -663,7 +863,7 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
*/
do_accounting = !IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu);
- for (i = 0; i < npage; i++) {
+ for (i = 0; i < npage; i += contiguous_npage) {
dma_addr_t iova;
struct vfio_pfn *vpfn;
@@ -682,31 +882,18 @@ static int vfio_iommu_type1_pin_pages(void *iommu_data,
vpfn = vfio_iova_get_vfio_pfn(dma, iova);
if (vpfn) {
phys_pfn[i] = vpfn->pfn;
- continue;
- }
-
- remote_vaddr = dma->vaddr + (iova - dma->iova);
- ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn[i],
- do_accounting);
- if (ret)
- goto pin_unwind;
-
- ret = vfio_add_to_pfn_list(dma, iova, phys_pfn[i]);
- if (ret) {
- if (put_pfn(phys_pfn[i], dma->prot) && do_accounting)
- vfio_lock_acct(dma, -1, true);
- goto pin_unwind;
- }
-
- if (iommu->dirty_page_tracking) {
- unsigned long pgshift = __ffs(iommu->pgsize_bitmap);
-
- /*
- * Bitmap populated with the smallest supported page
- * size
- */
- bitmap_set(dma->bitmap,
- (iova - dma->iova) >> pgshift, 1);
+ contiguous_npage = 1;
+ } else {
+ ret = vfio_iommu_type1_get_contiguous_pages_length(iommu,
+ &user_pfn[i], npage - i, prot);
+ if (ret < 0)
+ goto pin_unwind;
+
+ ret = vfio_iommu_type1_pin_contiguous_pages(iommu,
+ dma, &user_pfn[i], ret, &phys_pfn[i], do_accounting);
+ if (ret < 0)
+ goto pin_unwind;
+ contiguous_npage = ret;
}
}
ret = i;
--
2.19.1
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