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 X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 951F3C11D3D for ; Thu, 27 Feb 2020 14:46:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 59B1F24656 for ; Thu, 27 Feb 2020 14:46:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=shipmail.org header.i=@shipmail.org header.b="TBt3N1CI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730329AbgB0NpG (ORCPT ); Thu, 27 Feb 2020 08:45:06 -0500 Received: from ste-pvt-msa2.bahnhof.se ([213.80.101.71]:31464 "EHLO ste-pvt-msa2.bahnhof.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729725AbgB0No4 (ORCPT ); Thu, 27 Feb 2020 08:44:56 -0500 Received: from localhost (localhost [127.0.0.1]) by ste-pvt-msa2.bahnhof.se (Postfix) with ESMTP id D06D83FFFB; Thu, 27 Feb 2020 14:44:53 +0100 (CET) Authentication-Results: ste-pvt-msa2.bahnhof.se; dkim=pass (1024-bit key; unprotected) header.d=shipmail.org header.i=@shipmail.org header.b=TBt3N1CI; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at bahnhof.se Authentication-Results: ste-ftg-msa2.bahnhof.se (amavisd-new); dkim=pass (1024-bit key) header.d=shipmail.org Received: from ste-pvt-msa2.bahnhof.se ([127.0.0.1]) by localhost (ste-ftg-msa2.bahnhof.se [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id O5L8o1vP0Boy; Thu, 27 Feb 2020 14:44:53 +0100 (CET) Received: from mail1.shipmail.org (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) (Authenticated sender: mb878879) by ste-pvt-msa2.bahnhof.se (Postfix) with ESMTPA id E48103FFFD; Thu, 27 Feb 2020 14:44:50 +0100 (CET) Received: from localhost.localdomain (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) by mail1.shipmail.org (Postfix) with ESMTPSA id 37648360058; Thu, 27 Feb 2020 14:44:50 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=shipmail.org; s=mail; t=1582811090; bh=p0O7qg1HiipCWvP8nqnWxIx54P4BETutHnljdfP1p4g=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=TBt3N1CISeDTPgqNL1GPofJuBmCLEkHqs3jzcw52LvvJObksVGsOaFWLIcQGsf9nx mM5EA0rdFeR797YWf0ZuD0TGmFkywxVEIKm5Jr8GP/u/oylaEnn9oz3E3XZdB3Egj7 74AZzV8/36LXlBZ9MtjWJCkNzH5ImvJ3iXeAYX2M= Subject: Re: [PATCH v5 1/3] drm/shmem: add support for per object caching flags. To: Gerd Hoffmann Cc: dri-devel@lists.freedesktop.org, Guillaume.Gardet@arm.com, David Airlie , open list , gurchetansingh@chromium.org, tzimmermann@suse.de, yuq825@gmail.com, noralf@tronnes.org, robh@kernel.org References: <20200226154752.24328-1-kraxel@redhat.com> <20200226154752.24328-2-kraxel@redhat.com> <20200227075321.ki74hfjpnsqv2yx2@sirius.home.kraxel.org> <41ca197c-136a-75d8-b269-801db44d4cba@shipmail.org> <20200227105643.h4klc3ybhpwv2l3x@sirius.home.kraxel.org> <68a05ace-40bc-76d6-5464-2c96328874b9@shipmail.org> <20200227132137.irruicvlkxpdo3so@sirius.home.kraxel.org> From: =?UTF-8?Q?Thomas_Hellstr=c3=b6m_=28VMware=29?= Organization: VMware Inc. Message-ID: <78eb099e-020f-91d1-672e-15176bf12cd4@shipmail.org> Date: Thu, 27 Feb 2020 14:44:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200227132137.irruicvlkxpdo3so@sirius.home.kraxel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2/27/20 2:21 PM, Gerd Hoffmann wrote: > Hi, > >>> So I'd like to push patches 1+2 to -fixes and sort everything else later >>> in -next. OK? >> OK with me. > Done. > >>> [ context: why shmem helpers use pgprot_writecombine + pgprot_decrypted? >>> we get conflicting mappings because of that, linear kernel >>> map vs. gem object vmap/mmap ] >> Do we have any idea what drivers are actually using >> write-combine and decrypted? > drivers/gpu/drm# find -name Kconfig* -print | xargs grep -l DRM_GEM_SHMEM_HELPER > ./lima/Kconfig > ./tiny/Kconfig > ./cirrus/Kconfig > ./Kconfig > ./panfrost/Kconfig > ./udl/Kconfig > ./v3d/Kconfig > ./virtio/Kconfig > > virtio needs cached. > cirrus+udl should be ok with cached too. > > Not clue about the others (lima, tiny, panfrost, v3d). Maybe they use > write-combine just because this is what they got by default from > drm_gem_mmap_obj(). Maybe they actually need that. Trying to Cc: > maintainters (and drop stable@). > > On decrypted: I guess that is only relevant for virtual machines, i.e. > virtio-gpu and cirrus? > > virtio-gpu needs it, otherwise the host can't show the virtual display. > cirrus bounces everything via blits to vram, so it should be ok without > decrypted. I guess that implies we should make decrypted configurable. Decrypted here is clearly incorrect and violates the SEV spec, regardless of a config option. The only correct way is currently to use dma_alloc_coherent() and mmap_coherent() to allocate decrypted memory and then use the pgprot_decrypted flag. Since the same page is aliased with two physical addresses (one encrypted and one decrypted) switching memory from one to the other needs extensive handling even to flush stale vmaps... So if virtio-gpu needs it for some bos, it should move away from shmem for those bos. /Thomas > > cheers, > Gerd