Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932775AbdGCNoK (ORCPT ); Mon, 3 Jul 2017 09:44:10 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36514 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932738AbdGCNoD (ORCPT ); Mon, 3 Jul 2017 09:44:03 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lucas Stach , Wladimir van der Laan , Sasha Levin Subject: [PATCH 4.9 100/172] drm/etnaviv: trick drm_mm into giving out a low IOVA Date: Mon, 3 Jul 2017 15:34:40 +0200 Message-Id: <20170703133418.972621050@linuxfoundation.org> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170703133414.260777365@linuxfoundation.org> References: <20170703133414.260777365@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1529 Lines: 43 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lucas Stach [ Upstream commit 3546fb0cdac25a79c89d87020566fab52b92867d ] After rollover of the IOVA space, we want to get a low IOVA address, otherwise the the games we play by remembering the last IOVA are pointless. When we search for a free hole with DRM_MM_SEARCH_DEFAULT, drm_mm will pop the next entry from the free holes stack, which will likely be a high IOVA. By using DRM_MM_SEARCH_BELOW we can trick drm_mm into reversing the search and provide us with a low IOVA. Signed-off-by: Lucas Stach Reviewed-by: Wladimir van der Laan Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/etnaviv/etnaviv_mmu.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c @@ -116,9 +116,14 @@ static int etnaviv_iommu_find_iova(struc struct list_head list; bool found; + /* + * XXX: The DRM_MM_SEARCH_BELOW is really a hack to trick + * drm_mm into giving out a low IOVA after address space + * rollover. This needs a proper fix. + */ ret = drm_mm_insert_node_in_range(&mmu->mm, node, size, 0, mmu->last_iova, ~0UL, - DRM_MM_SEARCH_DEFAULT); + mmu->last_iova ? DRM_MM_SEARCH_DEFAULT : DRM_MM_SEARCH_BELOW); if (ret != -ENOSPC) break;