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From: John Garry <john.garry@huawei.com>
To: Xie Yongji <xieyongji@bytedance.com>, <mst@redhat.com>,
	<jasowang@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>,
	<joro@8bytes.org>, <gregkh@linuxfoundation.org>,
	<zhe.he@windriver.com>, <xiaodong.liu@intel.com>,
	<joe@perches.com>, <robin.murphy@arm.com>
Cc: <kvm@vger.kernel.org>, <netdev@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	<virtualization@lists.linux-foundation.org>,
	<iommu@lists.linux-foundation.org>, <songmuchun@bytedance.com>,
	<linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v11 10/12] vduse: Implement an MMU-based software IOTLB
Date: Fri, 27 Aug 2021 09:57:42 +0100	[thread overview]
Message-ID: <2d807de3-e245-c2fb-ae5d-7cacbe35dfcb@huawei.com> (raw)
In-Reply-To: <20210818120642.165-11-xieyongji@bytedance.com>

On 18/08/2021 13:06, Xie Yongji wrote:
> +
> +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;
> +
> +	/*
> +	 * Freeing non-power-of-two-sized allocations back into the IOVA caches
> +	 * will come back to bite us badly, so we have to waste a bit of space
> +	 * rounding up anything cacheable to make sure that can't happen. The
> +	 * order of the unadjusted size will still match upon freeing.
> +	 */
> +	if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
> +		iova_len = roundup_pow_of_two(iova_len);

Whether it's proper to use this "fast" API or not here, this seems to be 
copied verbatim from dma-iommu.c, which tells me that something should 
be factored out.

Indeed, this rounding up seems a requirement of the rcache, so not sure 
why this is not done there.

> +	iova_pfn = alloc_iova_fast(iovad, iova_len, limit >> shift, true);



  reply	other threads:[~2021-08-27  8:53 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18 12:06 [PATCH v11 00/12] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-08-18 12:06 ` [PATCH v11 01/12] iova: Export alloc_iova_fast() and free_iova_fast() Xie Yongji
2021-08-23  6:24   ` Jason Wang
2021-08-24 18:08   ` Michael S. Tsirkin
2021-08-25  9:55     ` Will Deacon
2021-08-25 10:39       ` John Garry
2021-08-25 12:17         ` Yongji Xie
2021-08-27  9:03           ` John Garry
2021-08-18 12:06 ` [PATCH v11 02/12] file: Export receive_fd() to modules Xie Yongji
2021-08-18 12:06 ` [PATCH v11 03/12] vdpa: Fix some coding style issues Xie Yongji
2021-08-23  6:27   ` Jason Wang
2021-08-24 11:09   ` Stefano Garzarella
2021-08-18 12:06 ` [PATCH v11 04/12] vdpa: Add reset callback in vdpa_config_ops Xie Yongji
2021-08-23  6:31   ` Jason Wang
2021-08-23  7:44     ` Yongji Xie
2021-08-18 12:06 ` [PATCH v11 05/12] vhost-vdpa: Handle the failure of vdpa_reset() Xie Yongji
2021-08-23  6:32   ` Jason Wang
2021-08-24 11:12   ` Stefano Garzarella
2021-08-18 12:06 ` [PATCH v11 06/12] vhost-iotlb: Add an opaque pointer for vhost IOTLB Xie Yongji
2021-08-18 12:06 ` [PATCH v11 07/12] vdpa: Add an opaque pointer for vdpa_config_ops.dma_map() Xie Yongji
2021-08-18 12:06 ` [PATCH v11 08/12] vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap() Xie Yongji
2021-08-18 12:06 ` [PATCH v11 09/12] vdpa: Support transferring virtual addressing during DMA mapping Xie Yongji
2021-08-18 12:06 ` [PATCH v11 10/12] vduse: Implement an MMU-based software IOTLB Xie Yongji
2021-08-27  8:57   ` John Garry [this message]
2021-08-27  9:25     ` Yongji Xie
2021-08-18 12:06 ` [PATCH v11 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-08-23  6:56   ` Jason Wang
2021-08-24 18:10   ` Michael S. Tsirkin
2021-08-25  5:37     ` Yongji Xie
2021-08-18 12:06 ` [PATCH v11 12/12] Documentation: Add documentation for VDUSE Xie Yongji
2021-08-23  6:57   ` Jason Wang
2021-08-23  7:54   ` Jason Wang

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