From: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com> To: Boris Ostrovsky <boris.ostrovsky@oracle.com>, Oleksandr Andrushchenko <andr2000@gmail.com>, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, airlied@linux.ie, daniel.vetter@intel.com, seanpaul@chromium.org, gustavo@padovan.org, jgross@suse.com, konrad.wilk@oracle.com Subject: Re: [PATCH 8/9] drm/xen-front: Implement GEM operations Date: Fri, 23 Feb 2018 17:35:40 +0200 [thread overview] Message-ID: <56c4a78b-356a-fb35-a97e-187581ae45ad@epam.com> (raw) In-Reply-To: <2f2c6fea-c0cb-e244-41f3-269db07986fc@oracle.com> On 02/23/2018 05:26 PM, Boris Ostrovsky wrote: > On 02/21/2018 03:03 AM, Oleksandr Andrushchenko wrote: >> +static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size) >> +{ >> + struct xen_drm_front_drm_info *drm_info = dev->dev_private; >> + struct xen_gem_object *xen_obj; >> + int ret; >> + >> + size = round_up(size, PAGE_SIZE); >> + xen_obj = gem_create_obj(dev, size); >> + if (IS_ERR_OR_NULL(xen_obj)) >> + return xen_obj; >> + >> + if (drm_info->cfg->be_alloc) { >> + /* >> + * backend will allocate space for this buffer, so >> + * only allocate array of pointers to pages >> + */ >> + xen_obj->be_alloc = true; > If be_alloc is a flag (which I am not sure about) --- should it be set > to true *after* you've successfully allocated your things? this is a configuration option telling about the way the buffer gets allocated: either by the frontend or backend (be_alloc -> buffer allocated by the backend) > >> + ret = gem_alloc_pages_array(xen_obj, size); >> + if (ret < 0) { >> + gem_free_pages_array(xen_obj); >> + goto fail; >> + } >> + >> + ret = alloc_xenballooned_pages(xen_obj->num_pages, >> + xen_obj->pages); > Why are you allocating balloon pages? in this use-case we map pages provided by the backend (yes, I know this can be a problem from both security POV and that DomU can die holding pages of Dom0 forever: but still it is a configuration option, so user decides if her use-case needs this and takes responsibility for such a decision). Please see description of the buffering modes in xen_drm_front.h specifically for backend allocated buffers: ******************************************************************************* * 2. Buffers allocated by the backend ******************************************************************************* * * This mode of operation is run-time configured via guest domain configuration * through XenStore entries. * * For systems which do not provide IOMMU support, but having specific * requirements for display buffers it is possible to allocate such buffers * at backend side and share those with the frontend. * For example, if host domain is 1:1 mapped and has DRM/GPU hardware expecting * physically contiguous memory, this allows implementing zero-copying * use-cases. > > -boris > >> + if (ret < 0) { >> + DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n", >> + xen_obj->num_pages, ret); >> + goto fail; >> + } >> + >> + return xen_obj; >> + } >> + /* >> + * need to allocate backing pages now, so we can share those >> + * with the backend >> + */ >> + xen_obj->num_pages = DIV_ROUND_UP(size, PAGE_SIZE); >> + xen_obj->pages = drm_gem_get_pages(&xen_obj->base); >> + if (IS_ERR_OR_NULL(xen_obj->pages)) { >> + ret = PTR_ERR(xen_obj->pages); >> + xen_obj->pages = NULL; >> + goto fail; >> + } >> + >> + return xen_obj; >> + >> +fail: >> + DRM_ERROR("Failed to allocate buffer with size %zu\n", size); >> + return ERR_PTR(ret); >> +} >> + >>
WARNING: multiple messages have this Message-ID (diff)
From: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com> To: Boris Ostrovsky <boris.ostrovsky@oracle.com>, Oleksandr Andrushchenko <andr2000@gmail.com>, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, airlied@linux.ie, daniel.vetter@intel.com, seanpaul@chromium.org, gustavo@padovan.org, jgross@suse.com, konrad.wilk@oracle.com Subject: Re: [PATCH 8/9] drm/xen-front: Implement GEM operations Date: Fri, 23 Feb 2018 17:35:40 +0200 [thread overview] Message-ID: <56c4a78b-356a-fb35-a97e-187581ae45ad@epam.com> (raw) In-Reply-To: <2f2c6fea-c0cb-e244-41f3-269db07986fc@oracle.com> On 02/23/2018 05:26 PM, Boris Ostrovsky wrote: > On 02/21/2018 03:03 AM, Oleksandr Andrushchenko wrote: >> +static struct xen_gem_object *gem_create(struct drm_device *dev, size_t size) >> +{ >> + struct xen_drm_front_drm_info *drm_info = dev->dev_private; >> + struct xen_gem_object *xen_obj; >> + int ret; >> + >> + size = round_up(size, PAGE_SIZE); >> + xen_obj = gem_create_obj(dev, size); >> + if (IS_ERR_OR_NULL(xen_obj)) >> + return xen_obj; >> + >> + if (drm_info->cfg->be_alloc) { >> + /* >> + * backend will allocate space for this buffer, so >> + * only allocate array of pointers to pages >> + */ >> + xen_obj->be_alloc = true; > If be_alloc is a flag (which I am not sure about) --- should it be set > to true *after* you've successfully allocated your things? this is a configuration option telling about the way the buffer gets allocated: either by the frontend or backend (be_alloc -> buffer allocated by the backend) > >> + ret = gem_alloc_pages_array(xen_obj, size); >> + if (ret < 0) { >> + gem_free_pages_array(xen_obj); >> + goto fail; >> + } >> + >> + ret = alloc_xenballooned_pages(xen_obj->num_pages, >> + xen_obj->pages); > Why are you allocating balloon pages? in this use-case we map pages provided by the backend (yes, I know this can be a problem from both security POV and that DomU can die holding pages of Dom0 forever: but still it is a configuration option, so user decides if her use-case needs this and takes responsibility for such a decision). Please see description of the buffering modes in xen_drm_front.h specifically for backend allocated buffers: ******************************************************************************* * 2. Buffers allocated by the backend ******************************************************************************* * * This mode of operation is run-time configured via guest domain configuration * through XenStore entries. * * For systems which do not provide IOMMU support, but having specific * requirements for display buffers it is possible to allocate such buffers * at backend side and share those with the frontend. * For example, if host domain is 1:1 mapped and has DRM/GPU hardware expecting * physically contiguous memory, this allows implementing zero-copying * use-cases. > > -boris > >> + if (ret < 0) { >> + DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n", >> + xen_obj->num_pages, ret); >> + goto fail; >> + } >> + >> + return xen_obj; >> + } >> + /* >> + * need to allocate backing pages now, so we can share those >> + * with the backend >> + */ >> + xen_obj->num_pages = DIV_ROUND_UP(size, PAGE_SIZE); >> + xen_obj->pages = drm_gem_get_pages(&xen_obj->base); >> + if (IS_ERR_OR_NULL(xen_obj->pages)) { >> + ret = PTR_ERR(xen_obj->pages); >> + xen_obj->pages = NULL; >> + goto fail; >> + } >> + >> + return xen_obj; >> + >> +fail: >> + DRM_ERROR("Failed to allocate buffer with size %zu\n", size); >> + return ERR_PTR(ret); >> +} >> + >> _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2018-02-23 15:35 UTC|newest] Thread overview: 165+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-02-21 8:03 [PATCH 0/9] drm/xen-front: Add support for Xen PV display frontend Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 1/9] drm/xen-front: Introduce Xen para-virtualized frontend driver Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:19 ` Juergen Gross 2018-02-21 8:19 ` Juergen Gross 2018-02-21 8:47 ` Oleksandr Andrushchenko 2018-02-21 8:47 ` Oleksandr Andrushchenko 2018-02-21 8:47 ` Oleksandr Andrushchenko 2018-02-21 9:09 ` Juergen Gross 2018-02-21 9:09 ` Juergen Gross 2018-02-21 9:11 ` Oleksandr Andrushchenko 2018-02-21 9:11 ` Oleksandr Andrushchenko 2018-02-21 9:11 ` Oleksandr Andrushchenko 2018-02-21 9:17 ` [Xen-devel] " Roger Pau Monné 2018-02-21 9:17 ` Roger Pau Monné 2018-02-21 9:42 ` [Xen-devel] " Oleksandr Andrushchenko 2018-02-21 9:42 ` Oleksandr Andrushchenko 2018-02-21 10:19 ` Roger Pau Monné 2018-02-21 10:19 ` Roger Pau Monné 2018-02-21 10:25 ` Oleksandr Andrushchenko 2018-02-21 10:25 ` [Xen-devel] " Oleksandr Andrushchenko 2018-02-21 10:25 ` Oleksandr Andrushchenko 2018-02-21 9:42 ` Oleksandr Andrushchenko 2018-02-22 22:23 ` Boris Ostrovsky 2018-02-22 22:23 ` Boris Ostrovsky 2018-02-23 6:37 ` Oleksandr Andrushchenko 2018-02-23 6:37 ` Oleksandr Andrushchenko 2018-02-23 14:39 ` Boris Ostrovsky 2018-02-23 14:39 ` Boris Ostrovsky 2018-02-23 14:51 ` Oleksandr Andrushchenko 2018-02-23 14:51 ` Oleksandr Andrushchenko 2018-02-23 14:51 ` Oleksandr Andrushchenko 2018-02-23 6:37 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 2/9] drm/xen-front: Implement Xen bus state handling Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:23 ` Juergen Gross 2018-02-21 8:23 ` Juergen Gross 2018-02-21 8:50 ` Oleksandr Andrushchenko 2018-02-21 8:50 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 3/9] drm/xen-front: Read driver configuration from Xen store Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-22 23:20 ` Boris Ostrovsky 2018-02-22 23:20 ` Boris Ostrovsky 2018-02-23 6:46 ` Oleksandr Andrushchenko 2018-02-23 6:46 ` Oleksandr Andrushchenko 2018-02-23 6:46 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 4/9] drm/xen-front: Implement Xen event channel handling Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-22 23:50 ` Boris Ostrovsky 2018-02-22 23:50 ` Boris Ostrovsky 2018-02-23 7:00 ` Oleksandr Andrushchenko 2018-02-23 7:00 ` Oleksandr Andrushchenko 2018-02-23 7:00 ` Oleksandr Andrushchenko 2018-02-23 14:44 ` Boris Ostrovsky 2018-02-23 14:44 ` Boris Ostrovsky 2018-02-23 14:49 ` Oleksandr Andrushchenko 2018-02-23 14:49 ` Oleksandr Andrushchenko 2018-02-23 14:49 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 5/9] drm/xen-front: Implement handling of shared display buffers Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-23 0:25 ` Boris Ostrovsky 2018-02-23 0:25 ` Boris Ostrovsky 2018-02-23 7:53 ` Oleksandr Andrushchenko 2018-02-23 7:53 ` Oleksandr Andrushchenko 2018-02-23 14:36 ` Boris Ostrovsky 2018-02-23 14:36 ` Boris Ostrovsky 2018-02-23 14:45 ` Oleksandr Andrushchenko 2018-02-23 14:45 ` Oleksandr Andrushchenko 2018-02-23 14:45 ` Oleksandr Andrushchenko 2018-02-23 7:53 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 6/9] drm/xen-front: Introduce DRM/KMS virtual display driver Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-23 15:12 ` Boris Ostrovsky 2018-02-23 15:12 ` Boris Ostrovsky 2018-02-23 15:19 ` Oleksandr Andrushchenko 2018-02-23 15:19 ` Oleksandr Andrushchenko 2018-02-23 15:19 ` Oleksandr Andrushchenko 2018-03-05 9:13 ` Daniel Vetter 2018-03-05 9:13 ` Daniel Vetter 2018-03-05 9:19 ` Oleksandr Andrushchenko 2018-03-05 9:19 ` Oleksandr Andrushchenko 2018-03-05 9:19 ` Oleksandr Andrushchenko 2018-03-05 9:13 ` Daniel Vetter 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 7/9] drm/xen-front: Implement KMS/connector handling Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-03-05 9:23 ` Daniel Vetter 2018-03-05 9:23 ` Daniel Vetter 2018-03-05 12:59 ` Oleksandr Andrushchenko 2018-03-05 12:59 ` Oleksandr Andrushchenko 2018-03-06 7:22 ` Daniel Vetter 2018-03-06 7:22 ` Daniel Vetter 2018-03-06 7:22 ` Daniel Vetter 2018-03-06 7:29 ` Oleksandr Andrushchenko 2018-03-06 7:29 ` Oleksandr Andrushchenko 2018-03-06 7:29 ` Oleksandr Andrushchenko 2018-03-05 12:59 ` Oleksandr Andrushchenko 2018-03-05 9:23 ` Daniel Vetter 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 8/9] drm/xen-front: Implement GEM operations Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-23 15:26 ` Boris Ostrovsky 2018-02-23 15:26 ` Boris Ostrovsky 2018-02-23 15:35 ` Oleksandr Andrushchenko [this message] 2018-02-23 15:35 ` Oleksandr Andrushchenko 2018-02-26 23:47 ` Boris Ostrovsky 2018-02-27 6:52 ` Oleksandr Andrushchenko 2018-02-27 6:52 ` Oleksandr Andrushchenko 2018-02-27 6:52 ` Oleksandr Andrushchenko 2018-02-28 19:46 ` Boris Ostrovsky 2018-02-28 19:46 ` Boris Ostrovsky 2018-02-28 19:52 ` Oleksandr Andrushchenko 2018-02-28 19:52 ` Oleksandr Andrushchenko 2018-02-28 19:52 ` Oleksandr Andrushchenko 2018-02-26 23:47 ` Boris Ostrovsky 2018-03-05 9:32 ` Daniel Vetter 2018-03-05 9:32 ` Daniel Vetter 2018-03-05 9:32 ` Daniel Vetter 2018-03-05 13:46 ` Oleksandr Andrushchenko 2018-03-05 13:46 ` Oleksandr Andrushchenko 2018-03-05 13:46 ` Oleksandr Andrushchenko 2018-03-06 7:26 ` Daniel Vetter 2018-03-06 7:43 ` Oleksandr Andrushchenko 2018-03-06 7:43 ` Oleksandr Andrushchenko 2018-03-06 7:26 ` Daniel Vetter 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-21 8:03 ` [PATCH 9/9] drm/xen-front: Implement communication with backend Oleksandr Andrushchenko 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-03-05 9:25 ` Daniel Vetter 2018-03-05 9:25 ` Daniel Vetter 2018-03-05 9:25 ` Daniel Vetter 2018-03-05 9:30 ` Oleksandr Andrushchenko 2018-03-05 9:30 ` Oleksandr Andrushchenko 2018-03-06 9:26 ` Daniel Vetter 2018-03-06 9:26 ` Daniel Vetter 2018-03-06 9:45 ` Oleksandr Andrushchenko 2018-03-06 9:45 ` Oleksandr Andrushchenko 2018-03-06 9:26 ` Daniel Vetter 2018-02-21 8:03 ` Oleksandr Andrushchenko 2018-02-26 8:21 ` [PATCH 0/9] drm/xen-front: Add support for Xen PV display frontend Oleksandr Andrushchenko 2018-02-26 8:21 ` Oleksandr Andrushchenko 2018-02-27 12:40 ` Oleksandr Andrushchenko 2018-02-27 12:40 ` Oleksandr Andrushchenko 2018-02-27 12:40 ` Oleksandr Andrushchenko 2018-02-28 14:08 ` [Xen-devel] " Julien Grall 2018-03-01 1:42 ` Stefano Stabellini 2018-03-01 1:42 ` [Xen-devel] " Stefano Stabellini 2018-03-01 1:42 ` Stefano Stabellini 2018-02-28 14:08 ` Julien Grall 2018-03-01 8:26 ` Gerd Hoffmann 2018-03-01 8:26 ` Gerd Hoffmann 2018-03-01 8:26 ` Gerd Hoffmann 2018-03-01 8:49 ` Oleksandr Andrushchenko 2018-03-01 8:49 ` Oleksandr Andrushchenko 2018-03-01 8:49 ` Oleksandr Andrushchenko 2018-02-26 8:21 ` Oleksandr Andrushchenko 2018-03-01 1:14 ` Stefano Stabellini 2018-03-01 1:14 ` Stefano Stabellini 2018-03-01 1:14 ` Stefano Stabellini
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