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Tue, 19 Jul 2022 23:03:51 -0700 (PDT) X-Google-Smtp-Source: AGRyM1tiFBhubKd+yx90qUOeMnSEQR5UGF9w2hH/iwB1U/cT6rqs3h+jXVZCY6Jz3ePcSOoR/PkOYDO8cOG0TUVSkQw= X-Received: by 2002:a05:6512:3f0e:b0:48a:5edd:99b2 with SMTP id y14-20020a0565123f0e00b0048a5edd99b2mr612996lfa.124.1658297031123; Tue, 19 Jul 2022 23:03:51 -0700 (PDT) MIME-Version: 1.0 References: <20220720044144.90-1-xieyongji@bytedance.com> <20220720044144.90-4-xieyongji@bytedance.com> In-Reply-To: <20220720044144.90-4-xieyongji@bytedance.com> From: Jason Wang Date: Wed, 20 Jul 2022 14:03:40 +0800 Message-ID: Subject: Re: [PATCH v3 3/5] vduse: Support using userspace pages as bounce buffer To: Xie Yongji Cc: mst , Liu Xiaodong , Maxime Coquelin , Stefan Hajnoczi , songmuchun@bytedance.com, virtualization , linux-kernel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 20, 2022 at 12:42 PM Xie Yongji wrote: > > Introduce two APIs: vduse_domain_add_user_bounce_pages() > and vduse_domain_remove_user_bounce_pages() to support > adding and removing userspace pages for bounce buffers. > During adding and removing, the DMA data would be copied > from the kernel bounce pages to the userspace bounce pages > and back. > > Signed-off-by: Xie Yongji Acked-by: Jason Wang > --- > drivers/vdpa/vdpa_user/iova_domain.c | 96 +++++++++++++++++++++++++--- > drivers/vdpa/vdpa_user/iova_domain.h | 8 +++ > 2 files changed, 96 insertions(+), 8 deletions(-) > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c > index 50d7c08d5450..e682bc7ee6c9 100644 > --- a/drivers/vdpa/vdpa_user/iova_domain.c > +++ b/drivers/vdpa/vdpa_user/iova_domain.c > @@ -178,8 +178,9 @@ static void vduse_domain_bounce(struct vduse_iova_domain *domain, > map->orig_phys == INVALID_PHYS_ADDR)) > return; > > - addr = page_address(map->bounce_page) + offset; > - do_bounce(map->orig_phys + offset, addr, sz, dir); > + addr = kmap_local_page(map->bounce_page); > + do_bounce(map->orig_phys + offset, addr + offset, sz, dir); > + kunmap_local(addr); > size -= sz; > iova += sz; > } > @@ -210,20 +211,23 @@ static struct page * > vduse_domain_get_bounce_page(struct vduse_iova_domain *domain, u64 iova) > { > struct vduse_bounce_map *map; > - struct page *page; > + struct page *page = NULL; > > + read_lock(&domain->bounce_lock); > map = &domain->bounce_maps[iova >> PAGE_SHIFT]; > - if (!map->bounce_page) > - return NULL; > + if (domain->user_bounce_pages || !map->bounce_page) > + goto out; > > page = map->bounce_page; > get_page(page); > +out: > + read_unlock(&domain->bounce_lock); > > return page; > } > > static void > -vduse_domain_free_bounce_pages(struct vduse_iova_domain *domain) > +vduse_domain_free_kernel_bounce_pages(struct vduse_iova_domain *domain) > { > struct vduse_bounce_map *map; > unsigned long pfn, bounce_pfns; > @@ -243,6 +247,73 @@ vduse_domain_free_bounce_pages(struct vduse_iova_domain *domain) > } > } > > +int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain, > + struct page **pages, int count) > +{ > + struct vduse_bounce_map *map; > + int i, ret; > + > + /* Now we don't support partial mapping */ > + if (count != (domain->bounce_size >> PAGE_SHIFT)) > + return -EINVAL; > + > + write_lock(&domain->bounce_lock); > + ret = -EEXIST; > + if (domain->user_bounce_pages) > + goto out; > + > + for (i = 0; i < count; i++) { > + map = &domain->bounce_maps[i]; > + if (map->bounce_page) { > + /* Copy kernel page to user page if it's in use */ > + if (map->orig_phys != INVALID_PHYS_ADDR) > + memcpy_to_page(pages[i], 0, > + page_address(map->bounce_page), > + PAGE_SIZE); > + __free_page(map->bounce_page); > + } > + map->bounce_page = pages[i]; > + get_page(pages[i]); > + } > + domain->user_bounce_pages = true; > + ret = 0; > +out: > + write_unlock(&domain->bounce_lock); > + > + return ret; > +} > + > +void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain) > +{ > + struct vduse_bounce_map *map; > + unsigned long i, count; > + > + write_lock(&domain->bounce_lock); > + if (!domain->user_bounce_pages) > + goto out; > + > + count = domain->bounce_size >> PAGE_SHIFT; > + for (i = 0; i < count; i++) { > + struct page *page = NULL; > + > + map = &domain->bounce_maps[i]; > + if (WARN_ON(!map->bounce_page)) > + continue; > + > + /* Copy user page to kernel page if it's in use */ > + if (map->orig_phys != INVALID_PHYS_ADDR) { > + page = alloc_page(GFP_ATOMIC | __GFP_NOFAIL); > + memcpy_from_page(page_address(page), > + map->bounce_page, 0, PAGE_SIZE); > + } > + put_page(map->bounce_page); > + map->bounce_page = page; > + } > + domain->user_bounce_pages = false; > +out: > + write_unlock(&domain->bounce_lock); > +} > + > void vduse_domain_reset_bounce_map(struct vduse_iova_domain *domain) > { > if (!domain->bounce_map) > @@ -318,13 +389,18 @@ dma_addr_t vduse_domain_map_page(struct vduse_iova_domain *domain, > if (vduse_domain_init_bounce_map(domain)) > goto err; > > + read_lock(&domain->bounce_lock); > if (vduse_domain_map_bounce_page(domain, (u64)iova, (u64)size, pa)) > - goto err; > + goto err_unlock; > > if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) > vduse_domain_bounce(domain, iova, size, DMA_TO_DEVICE); > > + read_unlock(&domain->bounce_lock); > + > return iova; > +err_unlock: > + read_unlock(&domain->bounce_lock); > err: > vduse_domain_free_iova(iovad, iova, size); > return DMA_MAPPING_ERROR; > @@ -336,10 +412,12 @@ void vduse_domain_unmap_page(struct vduse_iova_domain *domain, > { > struct iova_domain *iovad = &domain->stream_iovad; > > + read_lock(&domain->bounce_lock); > if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) > vduse_domain_bounce(domain, dma_addr, size, DMA_FROM_DEVICE); > > vduse_domain_unmap_bounce_page(domain, (u64)dma_addr, (u64)size); > + read_unlock(&domain->bounce_lock); > vduse_domain_free_iova(iovad, dma_addr, size); > } > > @@ -447,7 +525,8 @@ static int vduse_domain_release(struct inode *inode, struct file *file) > > spin_lock(&domain->iotlb_lock); > vduse_iotlb_del_range(domain, 0, ULLONG_MAX); > - vduse_domain_free_bounce_pages(domain); > + vduse_domain_remove_user_bounce_pages(domain); > + vduse_domain_free_kernel_bounce_pages(domain); > spin_unlock(&domain->iotlb_lock); > put_iova_domain(&domain->stream_iovad); > put_iova_domain(&domain->consistent_iovad); > @@ -507,6 +586,7 @@ vduse_domain_create(unsigned long iova_limit, size_t bounce_size) > goto err_file; > > domain->file = file; > + rwlock_init(&domain->bounce_lock); > spin_lock_init(&domain->iotlb_lock); > init_iova_domain(&domain->stream_iovad, > PAGE_SIZE, IOVA_START_PFN); > diff --git a/drivers/vdpa/vdpa_user/iova_domain.h b/drivers/vdpa/vdpa_user/iova_domain.h > index 2722d9b8e21a..4e0e50e7ac15 100644 > --- a/drivers/vdpa/vdpa_user/iova_domain.h > +++ b/drivers/vdpa/vdpa_user/iova_domain.h > @@ -14,6 +14,7 @@ > #include > #include > #include > +#include > > #define IOVA_START_PFN 1 > > @@ -34,6 +35,8 @@ struct vduse_iova_domain { > struct vhost_iotlb *iotlb; > spinlock_t iotlb_lock; > struct file *file; > + bool user_bounce_pages; > + rwlock_t bounce_lock; > }; > > int vduse_domain_set_map(struct vduse_iova_domain *domain, > @@ -61,6 +64,11 @@ void vduse_domain_free_coherent(struct vduse_iova_domain *domain, size_t size, > > void vduse_domain_reset_bounce_map(struct vduse_iova_domain *domain); > > +int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain, > + struct page **pages, int count); > + > +void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain); > + > void vduse_domain_destroy(struct vduse_iova_domain *domain); > > struct vduse_iova_domain *vduse_domain_create(unsigned long iova_limit, > -- > 2.20.1 >