From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753798AbdFQWgF (ORCPT ); Sat, 17 Jun 2017 18:36:05 -0400 Received: from omzsmtpe03.verizonbusiness.com ([199.249.25.208]:34376 "EHLO omzsmtpe03.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753317AbdFQWZy (ORCPT ); Sat, 17 Jun 2017 18:25:54 -0400 X-IronPort-Anti-Spam-Filtered: false From: "Levin, Alexander (Sasha Levin)" Cc: Lucas Stach , "Levin, Alexander (Sasha Levin)" X-IronPort-AV: E=Sophos;i="5.39,316,1493683200"; d="scan'208";a="372653807" To: "stable@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: [PATCH for v4.9 LTS 51/86] drm/etnaviv: trick drm_mm into giving out a low IOVA Thread-Topic: [PATCH for v4.9 LTS 51/86] drm/etnaviv: trick drm_mm into giving out a low IOVA Thread-Index: AQHS57iFRd+WN3u220Gk7TFn/5odpw== Date: Sat, 17 Jun 2017 22:24:45 +0000 Message-ID: <20170617222420.19316-51-alexander.levin@verizon.com> References: <20170617222420.19316-1-alexander.levin@verizon.com> In-Reply-To: <20170617222420.19316-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v5HMaP9K022895 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 --- drivers/gpu/drm/etnaviv/etnaviv_mmu.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/etnaviv/etnaviv_mmu.c b/drivers/gpu/drm/etnaviv/etnaviv_mmu.c index 169ac96e8f08..fe0e85b41310 100644 --- 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(struct etnaviv_iommu *mmu, 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; -- 2.11.0