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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?FW25mylLFsUnbbLT8GuwYAGaEQioW664t5vCnay2iSu3OQd+2u6/DkDH7qjI?= =?us-ascii?Q?Ek0cV7i3JV3XfPNAQiP0fJBSpBlDjcMfj3vjEw8J5EglI8S4rNWf3Q/6CcD0?= =?us-ascii?Q?PKphuhVwMhW/zIJ8P2fyM4mSXn2XhdP0gVGmlS6JiJ5JsnwatjmqQXzLqW6/?= =?us-ascii?Q?8oZZlNx0v1M9XcZUibQ0QGddVr+er4SdkukNda4sWU0Nsti0x+mCxm1SFLFa?= =?us-ascii?Q?zmPPMrul1K1850oHJ8W93Ka/loHPflZsVweFobJvR6Nb826D7qD9O2eF33wF?= =?us-ascii?Q?9WhAkDEymGOuIYTV7C+y52GdbHkQufFhhfSXp+zmNh2Iys7DHbPEcKl5IkRZ?= =?us-ascii?Q?jrMXPUDUjV2zPnIRRUqpn6Bgei2Hyr7bh6kv97rlOW7x9BTytq6T5gFIBpMn?= =?us-ascii?Q?O72FqHPxLPdxI9FN1T5RF6U8RILFYSa8YxA+LyVuphpf3oV6RosFpL+PxU26?= =?us-ascii?Q?zRzkRWMYkyNS+BIEcKCifVW5FzYaWDlyDtnL+AW2ULPNXS0+GL3zNS+hVqfA?= =?us-ascii?Q?5X6YZc0lWm4KkYNKJHlnYMdlOAhUeNWCQrZsjvI/SSd3m03MmS/zhAJrxLlg?= =?us-ascii?Q?9Kx4RV54uVqTCCGe0quqNkvENMv2Yg9fKI+DXWHOZOOC9MYiYbP0gVlzowxJ?= =?us-ascii?Q?J7qb2tfS5rJY86+i0rOd1QsmvMkyHh+GsxB382TB10kP8jf+3OA95njmd2ZY?= =?us-ascii?Q?QrY8DcKYGSpAnK4msb+4657yOkD6dWVArRy/uXEo/kgsG87u959niHCmwE+6?= =?us-ascii?Q?EoZ71IgHr8niNW3a07Wt7Hb+ciDBBxI6iy7NYiG25kZd6LXFDKv7qdHabrzJ?= =?us-ascii?Q?eBRbe3mczesu2zUY/76Ru701DXuipJsGCD4Wlo+nSN9fFy/Ssz8U/INbJeth?= =?us-ascii?Q?14vk3iAxp6Baq9u7hPYeQjKnUMuYof+Fg/nwyMDyOSTcavDMieO2gegvqC8k?= =?us-ascii?Q?ugJJJSTDhnyf1PrQKcbTTHhGOd5hV1l+BhrGwAiuEXldi9VTovGXi8BO86a2?= =?us-ascii?Q?J8V/APElEnYOVpD8G80jckvZFC58djyjJ5Gt1c9XL7vKOV/ef/vHXkkEMA6p?= =?us-ascii?Q?sdMgTlyrmYMUCitcmUVJScnqc4/IVXd5kBtFSvS8tE13cpgmPtDqbC9kBTkp?= =?us-ascii?Q?ylikwLBxW7QyngWXxjwnj5InqZeQPC99Gk0WBVwTtYkcr7Rea5jBi1U53gwP?= =?us-ascii?Q?ujCBJyZo0tACXECoFdKdhPR6RTafIkGRrpnyzCBLvnT7hdK1ZRESfaZmR95A?= =?us-ascii?Q?KQeHbq74sUkqs9yeCLmdgOEG3it+pYLB7iqJ8QTV/Lm51L4j210r0oNBQx3Z?= =?us-ascii?Q?XK0VsxaOSwGuAGr+Lh2Z+AR8eHK0n7e30iHOhI0VFBTVswsMJuRfHqGJpL+s?= =?us-ascii?Q?obc1VyF8phOecCuFcV4xMdbo202FhqdDgDO7vWRIottkcaLHcfOsEerXlwwq?= =?us-ascii?Q?k8K1OCvuEDvCmscIzpcGzO/JTV5kH1RJzHyU7IIZoHMTqboq4akWZOM25q9K?= =?us-ascii?Q?YYIPndM/Z+c0yigTr7ox8EYtwduj5Yazolf4jkt5Qu2IP39T+FbsI6KPNQsF?= =?us-ascii?Q?DJROoXT8hGBDA9SENdb66Bl7G0HQFRtP/QevXP+M?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: f95bc4ff-7b64-414a-86fc-08da5f7bbaf5 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Jul 2022 18:17:05.0646 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: O3a+ZyPY2LJd01cSjVrtFF5jWPWm/L5Fn056qIPPu+4tBX7vzDUfK4Mn7/tBjEKq X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR12MB4952 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 05, 2022 at 11:27:58PM -0700, Nicolin Chen wrote: > A PFN is not secure enough to promise that the memory is not IO. And > direct access via memcpy() that only handles CPU memory will crash on > S390 if the PFN is an IO PFN, as we have to use the memcpy_to/fromio() > that uses the special S390 IO access instructions. On the other hand, > a "struct page *" is always a CPU coherent thing that fits memcpy(). > > Also, casting a PFN to "void *" for memcpy() is not a proper practice, > kmap_local_page() is the correct API to call here, though S390 doesn't > use highmem, which means kmap_local_page() is a NOP. > > There's a following patch changing the vfio_pin_pages() API to return > a list of "struct page *" instead of PFNs. It will block any IO memory > from ever getting into this call path, for such a security purpose. In > this patch, add kmap_local_page() to prepare for that. > > Suggested-by: Jason Gunthorpe > Signed-off-by: Nicolin Chen > --- > drivers/s390/cio/vfio_ccw_cp.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) Reviewed-by: Jason Gunthorpe Jason From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F2EC4C433EF for ; Wed, 6 Jul 2022 18:17:16 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id EEF0610F318; Wed, 6 Jul 2022 18:17:13 +0000 (UTC) Received: from NAM10-MW2-obe.outbound.protection.outlook.com (mail-mw2nam10on2077.outbound.protection.outlook.com [40.107.94.77]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4E8C710F318; 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And > direct access via memcpy() that only handles CPU memory will crash on > S390 if the PFN is an IO PFN, as we have to use the memcpy_to/fromio() > that uses the special S390 IO access instructions. On the other hand, > a "struct page *" is always a CPU coherent thing that fits memcpy(). > > Also, casting a PFN to "void *" for memcpy() is not a proper practice, > kmap_local_page() is the correct API to call here, though S390 doesn't > use highmem, which means kmap_local_page() is a NOP. > > There's a following patch changing the vfio_pin_pages() API to return > a list of "struct page *" instead of PFNs. It will block any IO memory > from ever getting into this call path, for such a security purpose. In > this patch, add kmap_local_page() to prepare for that. > > Suggested-by: Jason Gunthorpe > Signed-off-by: Nicolin Chen > --- > drivers/s390/cio/vfio_ccw_cp.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) Reviewed-by: Jason Gunthorpe Jason From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 755B7C43334 for ; Wed, 6 Jul 2022 18:17:16 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7946210E8D6; Wed, 6 Jul 2022 18:17:13 +0000 (UTC) Received: from NAM10-MW2-obe.outbound.protection.outlook.com (mail-mw2nam10on2077.outbound.protection.outlook.com [40.107.94.77]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4E8C710F318; 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And > direct access via memcpy() that only handles CPU memory will crash on > S390 if the PFN is an IO PFN, as we have to use the memcpy_to/fromio() > that uses the special S390 IO access instructions. On the other hand, > a "struct page *" is always a CPU coherent thing that fits memcpy(). > > Also, casting a PFN to "void *" for memcpy() is not a proper practice, > kmap_local_page() is the correct API to call here, though S390 doesn't > use highmem, which means kmap_local_page() is a NOP. > > There's a following patch changing the vfio_pin_pages() API to return > a list of "struct page *" instead of PFNs. It will block any IO memory > from ever getting into this call path, for such a security purpose. In > this patch, add kmap_local_page() to prepare for that. > > Suggested-by: Jason Gunthorpe > Signed-off-by: Nicolin Chen > --- > drivers/s390/cio/vfio_ccw_cp.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) Reviewed-by: Jason Gunthorpe Jason