Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932905AbbKLXdz (ORCPT ); Thu, 12 Nov 2015 18:33:55 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:45475 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932507AbbKLXTm (ORCPT ); Thu, 12 Nov 2015 18:19:42 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Chris Wilson , Daniel Vetter , Tvrtko Ursulin , =?UTF-8?q?Micha=C5=82=20Winiarski?= , Jani Nikula , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 113/155] drm/i915: Deny wrapping an userptr into a framebuffer Date: Thu, 12 Nov 2015 15:17:47 -0800 Message-Id: <1447370309-357-114-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1447370309-357-1-git-send-email-kamal@canonical.com> References: <1447370309-357-1-git-send-email-kamal@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3222 Lines: 71 3.19.8-ckt10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Wilson commit cc917ab43541db3ff66d0136042686d40a1b4c9a upstream. Pinning a userptr onto the hardware raises interesting questions about the lifetime of such a surface as the framebuffer extends that life beyond the client's address space. That is the hardware will need to keep scanning out from the backing storage even after the client wants to remap its address space. As the hardware pins the backing storage, the userptr becomes invalid and this raises a WARN when the clients tries to unmap its address space. The situation can be even more complicated when the buffer is passed between processes, between a client and display server, where the lifetime and hardware access is even more confusing. Deny it. Signed-off-by: Chris Wilson Cc: Daniel Vetter Cc: Tvrtko Ursulin Cc: Michał Winiarski Reviewed-by: Tvrtko Ursulin Signed-off-by: Jani Nikula Signed-off-by: Kamal Mostafa --- drivers/gpu/drm/i915/i915_gem_userptr.c | 5 ++++- drivers/gpu/drm/i915/intel_display.c | 5 +++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index 1719078..ce175d0 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -776,7 +776,10 @@ static const struct drm_i915_gem_object_ops i915_gem_userptr_ops = { * Also note, that the object created here is not currently a "first class" * object, in that several ioctls are banned. These are the CPU access * ioctls: mmap(), pwrite and pread. In practice, you are expected to use - * direct access via your pointer rather than use those ioctls. + * direct access via your pointer rather than use those ioctls. Another + * restriction is that we do not allow userptr surfaces to be pinned to the + * hardware and so we reject any attempt to create a framebuffer out of a + * userptr. * * If you think this is a good interface to use to pass GPU memory between * drivers, please use dma-buf instead. In fact, wherever possible use diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index a67dde0..66adee1 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -12595,6 +12595,11 @@ static int intel_user_framebuffer_create_handle(struct drm_framebuffer *fb, struct intel_framebuffer *intel_fb = to_intel_framebuffer(fb); struct drm_i915_gem_object *obj = intel_fb->obj; + if (obj->userptr.mm) { + DRM_DEBUG("attempting to use a userptr for a framebuffer, denied\n"); + return -EINVAL; + } + return drm_gem_handle_create(file, &obj->base, handle); } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/