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From: Jason Wang <jasowang@redhat.com>
To: Xie Yongji <xieyongji@bytedance.com>,
	mst@redhat.com, stefanha@redhat.com, sgarzare@redhat.com,
	parav@nvidia.com, hch@infradead.org,
	christian.brauner@canonical.com, rdunlap@infradead.org,
	willy@infradead.org, viro@zeniv.linux.org.uk, axboe@kernel.dk,
	bcrl@kvack.org, corbet@lwn.net, mika.penttila@nextfour.com,
	dan.carpenter@oracle.com
Cc: virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, kvm@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v6 08/10] vduse: Implement an MMU-based IOMMU driver
Date: Thu, 8 Apr 2021 11:25:49 +0800	[thread overview]
Message-ID: <30862242-293b-f42f-d8ce-2c31a52e3697@redhat.com> (raw)
In-Reply-To: <20210331080519.172-9-xieyongji@bytedance.com>


在 2021/3/31 下午4:05, Xie Yongji 写道:
> This implements an MMU-based IOMMU driver to support mapping
> kernel dma buffer into userspace. The basic idea behind it is
> treating MMU (VA->PA) as IOMMU (IOVA->PA). The driver will set
> up MMU mapping instead of IOMMU mapping for the DMA transfer so
> that the userspace process is able to use its virtual address to
> access the dma buffer in kernel.
>
> And to avoid security issue, a bounce-buffering mechanism is
> introduced to prevent userspace accessing the original buffer
> directly.
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


Acked-by: Jason Wang <jasowang@redhat.com>

With some nits:


> ---
>   drivers/vdpa/vdpa_user/iova_domain.c | 521 +++++++++++++++++++++++++++++++++++
>   drivers/vdpa/vdpa_user/iova_domain.h |  70 +++++
>   2 files changed, 591 insertions(+)
>   create mode 100644 drivers/vdpa/vdpa_user/iova_domain.c
>   create mode 100644 drivers/vdpa/vdpa_user/iova_domain.h


[...]


> +static void vduse_domain_bounce(struct vduse_iova_domain *domain,
> +				dma_addr_t iova, size_t size,
> +				enum dma_data_direction dir)
> +{
> +	struct vduse_bounce_map *map;
> +	unsigned int offset;
> +	void *addr;
> +	size_t sz;
> +
> +	while (size) {
> +		map = &domain->bounce_maps[iova >> PAGE_SHIFT];
> +		offset = offset_in_page(iova);
> +		sz = min_t(size_t, PAGE_SIZE - offset, size);
> +
> +		if (WARN_ON(!map->bounce_page ||
> +			    map->orig_phys == INVALID_PHYS_ADDR))
> +			return;
> +
> +		addr = page_address(map->bounce_page) + offset;
> +		do_bounce(map->orig_phys + offset, addr, sz, dir);
> +		size -= sz;
> +		iova += sz;
> +	}
> +}
> +
> +static struct page *
> +vduse_domain_get_mapping_page(struct vduse_iova_domain *domain, u64 iova)


It's better to rename this as "vduse_domain_get_coherent_page?".


> +{
> +	u64 start = iova & PAGE_MASK;
> +	u64 last = start + PAGE_SIZE - 1;
> +	struct vhost_iotlb_map *map;
> +	struct page *page = NULL;
> +
> +	spin_lock(&domain->iotlb_lock);
> +	map = vhost_iotlb_itree_first(domain->iotlb, start, last);
> +	if (!map)
> +		goto out;
> +
> +	page = pfn_to_page((map->addr + iova - map->start) >> PAGE_SHIFT);
> +	get_page(page);
> +out:
> +	spin_unlock(&domain->iotlb_lock);
> +
> +	return page;
> +}
> +


[...]


> +
> +static dma_addr_t
> +vduse_domain_alloc_iova(struct iova_domain *iovad,
> +			unsigned long size, unsigned long limit)
> +{
> +	unsigned long shift = iova_shift(iovad);
> +	unsigned long iova_len = iova_align(iovad, size) >> shift;
> +	unsigned long iova_pfn;
> +
> +	if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
> +		iova_len = roundup_pow_of_two(iova_len);


Let's add a comment as what has been done in dma-iommu.c?

(In the future, it looks to me it's better to move them to 
alloc_iova_fast()).

Thanks



  reply	other threads:[~2021-04-08  3:26 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-31  8:05 [PATCH v6 00/10] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-03-31  8:05 ` [PATCH v6 01/10] file: Export receive_fd() to modules Xie Yongji
2021-03-31  9:15   ` Christian Brauner
2021-03-31  9:26     ` Dan Carpenter
2021-03-31  9:28       ` Christian Brauner
2021-03-31 11:32     ` Yongji Xie
2021-03-31 12:23       ` Christian Brauner
2021-03-31 13:59         ` Yongji Xie
2021-03-31 14:07           ` Christian Brauner
2021-03-31 14:37             ` Yongji Xie
2021-03-31  8:05 ` [PATCH v6 02/10] eventfd: Increase the recursion depth of eventfd_signal() Xie Yongji
2021-03-31  8:05 ` [PATCH v6 03/10] vhost-vdpa: protect concurrent access to vhost device iotlb Xie Yongji
2021-04-09 16:15   ` Michael S. Tsirkin
2021-04-11  5:36     ` Yongji Xie
2021-04-11 20:48       ` Michael S. Tsirkin
2021-04-12  2:29         ` Yongji Xie
2021-04-12  9:00           ` Michael S. Tsirkin
2021-03-31  8:05 ` [PATCH v6 04/10] vhost-iotlb: Add an opaque pointer for vhost IOTLB Xie Yongji
2021-03-31  8:05 ` [PATCH v6 05/10] vdpa: Add an opaque pointer for vdpa_config_ops.dma_map() Xie Yongji
2021-03-31  8:05 ` [PATCH v6 06/10] vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap() Xie Yongji
2021-03-31  8:05 ` [PATCH v6 07/10] vdpa: Support transferring virtual addressing during DMA mapping Xie Yongji
2021-04-08  2:36   ` Jason Wang
2021-03-31  8:05 ` [PATCH v6 08/10] vduse: Implement an MMU-based IOMMU driver Xie Yongji
2021-04-08  3:25   ` Jason Wang [this message]
2021-04-08  5:27     ` Yongji Xie
2021-03-31  8:05 ` [PATCH v6 09/10] vduse: Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-04-08  6:57   ` Jason Wang
2021-04-08  9:36     ` Yongji Xie
2021-04-09  5:36       ` Jason Wang
2021-04-09  8:02         ` Yongji Xie
2021-04-12  7:16           ` Jason Wang
2021-04-12  8:02             ` Yongji Xie
2021-04-12  9:37               ` Jason Wang
2021-04-12  9:59                 ` Yongji Xie
2021-04-13  3:35                   ` Jason Wang
2021-04-13  4:28                     ` Yongji Xie
2021-04-14  8:18                       ` Jason Wang
2021-04-16  3:24   ` Jason Wang
2021-04-16  8:43     ` Yongji Xie
2021-03-31  8:05 ` [PATCH v6 10/10] Documentation: Add documentation for VDUSE Xie Yongji
2021-04-08  7:18   ` Jason Wang
2021-04-08  8:09     ` Yongji Xie
2021-04-14 14:14   ` Stefan Hajnoczi
2021-04-15  5:38     ` Yongji Xie
2021-04-15  7:19       ` Stefan Hajnoczi
2021-04-15  8:33         ` Yongji Xie
2021-04-15 14:17           ` Stefan Hajnoczi
2021-04-15  8:36         ` Jason Wang
2021-04-15  9:04           ` Jason Wang
2021-04-15 11:17             ` Yongji Xie
2021-04-16  2:20               ` Jason Wang
2021-04-16  2:58                 ` Yongji Xie
2021-04-16  3:02                   ` Jason Wang
2021-04-16  3:18                     ` Yongji Xie
2021-04-15 14:38           ` Stefan Hajnoczi
2021-04-16  2:23             ` Jason Wang
2021-04-16  3:19               ` Yongji Xie
2021-04-16  5:39                 ` Jason Wang
2021-04-16  3:13             ` Yongji Xie
2021-04-14  7:34 ` [PATCH v6 00/10] Introduce VDUSE - vDPA Device in Userspace Michael S. Tsirkin
2021-04-14  7:49   ` Jason Wang
2021-04-14  7:54   ` Yongji Xie

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