From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966393AbeE2THV (ORCPT ); Tue, 29 May 2018 15:07:21 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:52486 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966338AbeE2THN (ORCPT ); Tue, 29 May 2018 15:07:13 -0400 Subject: Re: [PATCH 3/8] xen/grant-table: Allow allocating buffers suitable for DMA To: Oleksandr Andrushchenko , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, jgross@suse.com, konrad.wilk@oracle.com Cc: daniel.vetter@intel.com, dongwon.kim@intel.com, matthew.d.roper@intel.com, Oleksandr Andrushchenko References: <20180525153331.31188-1-andr2000@gmail.com> <20180525153331.31188-4-andr2000@gmail.com> From: Boris Ostrovsky Openpgp: preference=signencrypt Autocrypt: addr=boris.ostrovsky@oracle.com; prefer-encrypt=mutual; keydata= xsFNBFH8CgsBEAC0KiOi9siOvlXatK2xX99e/J3OvApoYWjieVQ9232Eb7GzCWrItCzP8FUV PQg8rMsSd0OzIvvjbEAvaWLlbs8wa3MtVLysHY/DfqRK9Zvr/RgrsYC6ukOB7igy2PGqZd+M MDnSmVzik0sPvB6xPV7QyFsykEgpnHbvdZAUy/vyys8xgT0PVYR5hyvhyf6VIfGuvqIsvJw5 C8+P71CHI+U/IhsKrLrsiYHpAhQkw+Zvyeml6XSi5w4LXDbF+3oholKYCkPwxmGdK8MUIdkM d7iYdKqiP4W6FKQou/lC3jvOceGupEoDV9botSWEIIlKdtm6C4GfL45RD8V4B9iy24JHPlom woVWc0xBZboQguhauQqrBFooHO3roEeM1pxXjLUbDtH4t3SAI3gt4dpSyT3EvzhyNQVVIxj2 FXnIChrYxR6S0ijSqUKO0cAduenhBrpYbz9qFcB/GyxD+ZWY7OgQKHUZMWapx5bHGQ8bUZz2 SfjZwK+GETGhfkvNMf6zXbZkDq4kKB/ywaKvVPodS1Poa44+B9sxbUp1jMfFtlOJ3AYB0WDS Op3d7F2ry20CIf1Ifh0nIxkQPkTX7aX5rI92oZeu5u038dHUu/dO2EcuCjl1eDMGm5PLHDSP 0QUw5xzk1Y8MG1JQ56PtqReO33inBXG63yTIikJmUXFTw6lLJwARAQABzTNCb3JpcyBPc3Ry b3Zza3kgKFdvcmspIDxib3Jpcy5vc3Ryb3Zza3lAb3JhY2xlLmNvbT7CwXgEEwECACIFAlH8 CgsCGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEIredpCGysGyasEP/j5xApopUf4g 9Fl3UxZuBx+oduuw3JHqgbGZ2siA3EA4bKwtKq8eT7ekpApn4c0HA8TWTDtgZtLSV5IdH+9z JimBDrhLkDI3Zsx2CafL4pMJvpUavhc5mEU8myp4dWCuIylHiWG65agvUeFZYK4P33fGqoaS VGx3tsQIAr7MsQxilMfRiTEoYH0WWthhE0YVQzV6kx4wj4yLGYPPBtFqnrapKKC8yFTpgjaK jImqWhU9CSUAXdNEs/oKVR1XlkDpMCFDl88vKAuJwugnixjbPFTVPyoC7+4Bm/FnL3iwlJVE qIGQRspt09r+datFzPqSbp5Fo/9m4JSvgtPp2X2+gIGgLPWp2ft1NXHHVWP19sPgEsEJXSr9 tskM8ScxEkqAUuDs6+x/ISX8wa5Pvmo65drN+JWA8EqKOHQG6LUsUdJolFM2i4Z0k40BnFU/ kjTARjrXW94LwokVy4x+ZYgImrnKWeKac6fMfMwH2aKpCQLlVxdO4qvJkv92SzZz4538az1T m+3ekJAimou89cXwXHCFb5WqJcyjDfdQF857vTn1z4qu7udYCuuV/4xDEhslUq1+GcNDjAhB nNYPzD+SvhWEsrjuXv+fDONdJtmLUpKs4Jtak3smGGhZsqpcNv8nQzUGDQZjuCSmDqW8vn2o hWwveNeRTkxh+2x1Qb3GT46uzsFNBFH8CgsBEADGC/yx5ctcLQlB9hbq7KNqCDyZNoYu1HAB Hal3MuxPfoGKObEktawQPQaSTB5vNlDxKihezLnlT/PKjcXC2R1OjSDinlu5XNGc6mnky03q yymUPyiMtWhBBftezTRxWRslPaFWlg/h/Y1iDuOcklhpr7K1h1jRPCrf1yIoxbIpDbffnuyz kuto4AahRvBU4Js4sU7f/btU+h+e0AcLVzIhTVPIz7PM+Gk2LNzZ3/on4dnEc/qd+ZZFlOQ4 KDN/hPqlwA/YJsKzAPX51L6Vv344pqTm6Z0f9M7YALB/11FO2nBB7zw7HAUYqJeHutCwxm7i BDNt0g9fhviNcJzagqJ1R7aPjtjBoYvKkbwNu5sWDpQ4idnsnck4YT6ctzN4I+6lfkU8zMzC gM2R4qqUXmxFIS4Bee+gnJi0Pc3KcBYBZsDK44FtM//5Cp9DrxRQOh19kNHBlxkmEb8kL/pw XIDcEq8MXzPBbxwHKJ3QRWRe5jPNpf8HCjnZz0XyJV0/4M1JvOua7IZftOttQ6KnM4m6WNIZ 2ydg7dBhDa6iv1oKdL7wdp/rCulVWn8R7+3cRK95SnWiJ0qKDlMbIN8oGMhHdin8cSRYdmHK kTnvSGJNlkis5a+048o0C6jI3LozQYD/W9wq7MvgChgVQw1iEOB4u/3FXDEGulRVko6xCBU4 SQARAQABwsFfBBgBAgAJBQJR/AoLAhsMAAoJEIredpCGysGyfvMQAIywR6jTqix6/fL0Ip8G jpt3uk//QNxGJE3ZkUNLX6N786vnEJvc1beCu6EwqD1ezG9fJKMl7F3SEgpYaiKEcHfoKGdh 30B3Hsq44vOoxR6zxw2B/giADjhmWTP5tWQ9548N4VhIZMYQMQCkdqaueSL+8asp8tBNP+TJ PAIIANYvJaD8xA7sYUXGTzOXDh2THWSvmEWWmzok8er/u6ZKdS1YmZkUy8cfzrll/9hiGCTj u3qcaOM6i/m4hqtvsI1cOORMVwjJF4+IkC5ZBoeRs/xW5zIBdSUoC8L+OCyj5JETWTt40+lu qoqAF/AEGsNZTrwHJYu9rbHH260C0KYCNqmxDdcROUqIzJdzDKOrDmebkEVnxVeLJBIhYZUd t3Iq9hdjpU50TA6sQ3mZxzBdfRgg+vaj2DsJqI5Xla9QGKD+xNT6v14cZuIMZzO7w0DoojM4 ByrabFsOQxGvE0w9Dch2BDSI2Xyk1zjPKxG1VNBQVx3flH37QDWpL2zlJikW29Ws86PHdthh Fm5PY8YtX576DchSP6qJC57/eAAe/9ztZdVAdesQwGb9hZHJc75B+VNm4xrh/PJO6c1THqdQ 19WVJ+7rDx3PhVncGlbAOiiiE3NOFPJ1OQYxPKtpBUukAlOTnkKE6QcA4zckFepUkfmBV1wM Jg6OxFYd01z+a+oL Message-ID: <94de6bd7-405c-c43f-0468-be71efff7552@oracle.com> Date: Tue, 29 May 2018 15:10:08 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180525153331.31188-4-andr2000@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8908 signatures=668702 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1805290203 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote: > From: Oleksandr Andrushchenko > > Extend grant table module API to allow allocating buffers that can > be used for DMA operations and mapping foreign grant references > on top of those. > The resulting buffer is similar to the one allocated by the balloon > driver in terms that proper memory reservation is made > ({increase|decrease}_reservation and VA mappings updated if needed). > This is useful for sharing foreign buffers with HW drivers which > cannot work with scattered buffers provided by the balloon driver, > but require DMAable memory instead. > > Signed-off-by: Oleksandr Andrushchenko > --- > drivers/xen/Kconfig | 13 ++++ > drivers/xen/grant-table.c | 124 ++++++++++++++++++++++++++++++++++++++ > include/xen/grant_table.h | 25 ++++++++ > 3 files changed, 162 insertions(+) > > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig > index e5d0c28372ea..3431fe210624 100644 > --- a/drivers/xen/Kconfig > +++ b/drivers/xen/Kconfig > @@ -161,6 +161,19 @@ config XEN_GRANT_DEV_ALLOC > to other domains. This can be used to implement frontend drivers > or as part of an inter-domain shared memory channel. > > +config XEN_GRANT_DMA_ALLOC > + bool "Allow allocating DMA capable buffers with grant reference module" > + depends on XEN Should it depend on anything from DMA? CONFIG_HAS_DMA for example? > + help > + Extends grant table module API to allow allocating DMA capable > + buffers and mapping foreign grant references on top of it. > + The resulting buffer is similar to one allocated by the balloon > + driver in terms that proper memory reservation is made > + ({increase|decrease}_reservation and VA mappings updated if needed). > + This is useful for sharing foreign buffers with HW drivers which > + cannot work with scattered buffers provided by the balloon driver, > + but require DMAable memory instead. > + > config SWIOTLB_XEN > def_bool y > select SWIOTLB > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index d7488226e1f2..06fe6e7f639c 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -45,6 +45,9 @@ > #include > #include > #include > +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC > +#include > +#endif > > #include > #include > @@ -57,6 +60,7 @@ > #ifdef CONFIG_X86 > #include > #endif > +#include > #include > #include > > @@ -811,6 +815,82 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages) > } > EXPORT_SYMBOL(gnttab_alloc_pages); > > +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC > +/** > + * gnttab_dma_alloc_pages - alloc DMAable pages suitable for grant mapping into > + * @args: arguments to the function > + */ > +int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args) > +{ > + unsigned long pfn, start_pfn; > + xen_pfn_t *frames; > + size_t size; > + int i, ret; > + > + frames = kcalloc(args->nr_pages, sizeof(*frames), GFP_KERNEL); > + if (!frames) > + return -ENOMEM; > + > + size = args->nr_pages << PAGE_SHIFT; > + if (args->coherent) > + args->vaddr = dma_alloc_coherent(args->dev, size, > + &args->dev_bus_addr, > + GFP_KERNEL | __GFP_NOWARN); > + else > + args->vaddr = dma_alloc_wc(args->dev, size, > + &args->dev_bus_addr, > + GFP_KERNEL | __GFP_NOWARN); > + if (!args->vaddr) { > + pr_err("Failed to allocate DMA buffer of size %zu\n", size); > + ret = -ENOMEM; > + goto fail_free_frames; > + } > + > + start_pfn = __phys_to_pfn(args->dev_bus_addr); > + for (pfn = start_pfn, i = 0; pfn < start_pfn + args->nr_pages; > + pfn++, i++) { > + struct page *page = pfn_to_page(pfn); > + > + args->pages[i] = page; > + frames[i] = xen_page_to_gfn(page); > + xenmem_reservation_scrub_page(page); > + } > + > + xenmem_reservation_va_mapping_reset(args->nr_pages, args->pages); > + > + ret = xenmem_reservation_decrease(args->nr_pages, frames); > + if (ret != args->nr_pages) { > + pr_err("Failed to decrease reservation for DMA buffer\n"); > + xenmem_reservation_increase(ret, frames); > + ret = -EFAULT; > + goto fail_free_dma; > + } > + > + ret = gnttab_pages_set_private(args->nr_pages, args->pages); > + if (ret < 0) > + goto fail_clear_private; > + > + kfree(frames); > + return 0; > + > +fail_clear_private: > + gnttab_pages_clear_private(args->nr_pages, args->pages); > +fail_free_dma: Do you need to xenmem_reservation_increase()? > + xenmem_reservation_va_mapping_update(args->nr_pages, args->pages, > + frames); > + if (args->coherent) > + dma_free_coherent(args->dev, size, > + args->vaddr, args->dev_bus_addr); > + else > + dma_free_wc(args->dev, size, > + args->vaddr, args->dev_bus_addr); > +fail_free_frames: > + kfree(frames); > + return ret; > +} > +EXPORT_SYMBOL(gnttab_dma_alloc_pages); > +#endif > + > void gnttab_pages_clear_private(int nr_pages, struct page **pages) > { > int i; > @@ -838,6 +918,50 @@ void gnttab_free_pages(int nr_pages, struct page **pages) > } > EXPORT_SYMBOL(gnttab_free_pages); > > +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC > +/** > + * gnttab_dma_free_pages - free DMAable pages > + * @args: arguments to the function > + */ > +int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args) > +{ > + xen_pfn_t *frames; > + size_t size; > + int i, ret; > + > + gnttab_pages_clear_private(args->nr_pages, args->pages); > + > + frames = kcalloc(args->nr_pages, sizeof(*frames), GFP_KERNEL); Any way you can do it without allocating memory? One possibility is to keep allocated frames from gnttab_dma_alloc_pages(). (Not sure I like that either but it's the only thing I can think of). > + if (!frames) > + return -ENOMEM; > + > + for (i = 0; i < args->nr_pages; i++) > + frames[i] = page_to_xen_pfn(args->pages[i]); Not xen_page_to_gfn()? > + > + ret = xenmem_reservation_increase(args->nr_pages, frames); > + if (ret != args->nr_pages) { > + pr_err("Failed to decrease reservation for DMA buffer\n"); > + ret = -EFAULT; > + } else { > + ret = 0; > + } > + > + xenmem_reservation_va_mapping_update(args->nr_pages, args->pages, > + frames); > + > + size = args->nr_pages << PAGE_SHIFT; > + if (args->coherent) > + dma_free_coherent(args->dev, size, > + args->vaddr, args->dev_bus_addr); > + else > + dma_free_wc(args->dev, size, > + args->vaddr, args->dev_bus_addr); > + kfree(frames); > + return ret; > +} > +EXPORT_SYMBOL(gnttab_dma_free_pages); > +#endif > + > /* Handling of paged out grant targets (GNTST_eagain) */ > #define MAX_DELAY 256 > static inline void > diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h > index de03f2542bb7..982e34242b9c 100644 > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -198,6 +198,31 @@ void gnttab_free_auto_xlat_frames(void); > int gnttab_alloc_pages(int nr_pages, struct page **pages); > void gnttab_free_pages(int nr_pages, struct page **pages); > > +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC > +struct gnttab_dma_alloc_args { > + /* Device for which DMA memory will be/was allocated. */ > + struct device *dev; > + /* > + * If set then DMA buffer is coherent and write-combine otherwise. > + */ Single-line comment > + bool coherent; > + /* > + * Number of entries in the @pages array, defines the size > + * of the DMA buffer. > + */ This can be made into single line comment as well. However, I am not sure this comment as well as those below are necessary. Fields names are self-describing IMO. -boris > + int nr_pages; > + /* Array of pages @pages filled with pages of the DMA buffer. */ > + struct page **pages; > + /* Virtual/CPU address of the DMA buffer. */ > + void *vaddr; > + /* Bus address of the DMA buffer. */ > + dma_addr_t dev_bus_addr; > +}; > + > +int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args); > +int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args); > +#endif > + > int gnttab_pages_set_private(int nr_pages, struct page **pages); > void gnttab_pages_clear_private(int nr_pages, struct page **pages); >