From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from madrid.collaboradmins.com (madrid.collaboradmins.com [46.235.227.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6B81F12C7EF for ; Tue, 5 Mar 2024 21:59:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=46.235.227.194 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709675947; cv=none; b=Qo7xbyBuNB+Qp1DEzbNbMr4XYl6dSprRZ0AtVVQqZB1hlwDKiQOYmENDCOQL/aoElHSLdonuZ1n+P4/M7+XNG3y/rDD2UYywFGF9qWe03UmRWm3+kCYEnBTWP57nx7jBN+KFJ9BsQlGEbK3wlTmrn+D2mZohreCK6ATRzXcjFA8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709675947; c=relaxed/simple; bh=Pi6T1W5bDFqqI2XXQ+4KYgY88rVQ95Vyl3n/fcXtOEo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WbvejSApXVUza/u5p1TU97nE1xMkrAXqO5wIE9JBsDOGE4pwY+XH/6KJgj5jwE/qa2lESMxdnGTM7FZJYYVdEEHKdcw3UQtnE169MHPt/R9b9vdfZo/VdlgBqsyzGZEiFwl4FJ+Fi5QJBMLUVTwY553WPFNBxkFoVfFFb6N80J0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=eK71pGBZ; arc=none smtp.client-ip=46.235.227.194 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="eK71pGBZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1709675943; bh=Pi6T1W5bDFqqI2XXQ+4KYgY88rVQ95Vyl3n/fcXtOEo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=eK71pGBZ6Cz51o8qikvWm9K+PhISQRoVeIfPrE1JiwaG7q1A3dZgkjtiTAbgZgp4B m69Q9A106Ja++jlIoMXxTtnhwo2cpnaGCPXX+0rOsMd7edcefjvG+OthSgVAm0YG+f 84likditwTT7tx9UMns7EZBUfNHVdaIggZo1SEbHhX2IVe3jHtEaJO1DB/Xtbr53Hk BCF2Q3TBsTYA3Lh7WSssBcx882ZZbaRRWyKc6XKmxYGQjlL0JzyxoACxfQkGzlgTS5 NfyWcJb5SAZclkjKZJdvPiySMBpD7/0op+jwvAnR0C3GCqBiyzqwaht8c3ZJeFNSQ6 nfSnf4FKoD2aw== Received: from [100.109.49.129] (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dmitry.osipenko) by madrid.collaboradmins.com (Postfix) with ESMTPSA id 64017378149B; Tue, 5 Mar 2024 21:59:01 +0000 (UTC) Message-ID: Date: Wed, 6 Mar 2024 00:58:58 +0300 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 00/13] drm: Fix reservation locking for pin/unpin and console Content-Language: en-US To: Thomas Zimmermann , daniel@ffwll.ch, airlied@gmail.com, mripard@kernel.org, maarten.lankhorst@linux.intel.com, christian.koenig@amd.com, sumit.semwal@linaro.org, robdclark@gmail.com, quic_abhinavk@quicinc.com, dmitry.baryshkov@linaro.org, sean@poorly.run, marijn.suijten@somainline.org, suijingfeng@loongson.cn, kherbst@redhat.com, lyude@redhat.com, dakr@redhat.com, airlied@redhat.com, kraxel@redhat.com, alexander.deucher@amd.com, Xinhui.Pan@amd.com, zack.rusin@broadcom.com, bcm-kernel-feedback-list@broadcom.com Cc: dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, nouveau@lists.freedesktop.org, virtualization@lists.linux.dev, spice-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org References: <20240227113853.8464-1-tzimmermann@suse.de> From: Dmitry Osipenko In-Reply-To: <20240227113853.8464-1-tzimmermann@suse.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/27/24 13:14, Thomas Zimmermann wrote: > Dma-buf locking semantics require the caller of pin and unpin to hold > the buffer's reservation lock. Fix DRM to adhere to the specs. This > enables to fix the locking in DRM's console emulation. Similar changes > for vmap and mmap have been posted at [1][2] > > Most DRM drivers and memory managers acquire the buffer object's > reservation lock within their GEM pin and unpin callbacks. This > violates dma-buf locking semantics. We get away with it because PRIME > does not provide pin/unpin, but attach/detach, for which the locking > semantics is correct. > > Patches 1 to 8 rework DRM GEM code in various implementations to > acquire the reservation lock when entering the pin and unpin callbacks. > This prepares them for the next patch. Drivers that are not affected > by these patches either don't acquire the reservation lock (amdgpu) > or don't need preparation (loongson). > > Patch 9 moves reservation locking from the GEM pin/unpin callbacks > into drm_gem_pin() and drm_gem_unpin(). As PRIME uses these functions > internally it still gets the reservation lock. > > With the updated GEM callbacks, the rest of the patchset fixes the > fbdev emulation's buffer locking. Fbdev emulation needs to keep its > GEM buffer object inplace while updating its content. This required > a implicit pinning and apparently amdgpu didn't do this at all. > > Patch 10 introduces drm_client_buffer_vmap_local() and _vunmap_local(). > The former function map a GEM buffer into the kernel's address space > with regular vmap operations, but keeps holding the reservation lock. > The _vunmap_local() helper undoes the vmap and releases the lock. The > updated GEM callbacks make this possible. Between the two calls, the > fbdev emulation can update the buffer content without have the buffer > moved or evicted. Update fbdev-generic to use vmap_local helpers, > which fix amdgpu. The idea of adding a "local vmap" has previously been > attempted at [3] in a different form. > > Patch 11 adds implicit pinning to the DRM client's regular vmap > helper so that long-term vmap'ed buffers won't be evicted. This only > affects fbdev-dma, but GEM DMA helpers don't require pinning. So > there are no practical changes. > > Patches 12 and 13 remove implicit pinning from the vmap and vunmap > operations in gem-vram and qxl. These pin operations are not supposed > to be part of vmap code, but were required to keep the buffers in place > for fbdev emulation. With the conversion o ffbdev-generic to to > vmap_local helpers, that code can finally be removed. > > Tested with amdgpu, nouveau, radeon, simpledrm and vc4. > > [1] https://patchwork.freedesktop.org/series/106371/ > [2] https://patchwork.freedesktop.org/series/116001/ > [3] https://patchwork.freedesktop.org/series/84732/ > > Thomas Zimmermann (13): > drm/gem-shmem: Acquire reservation lock in GEM pin/unpin callbacks > drm/gem-vram: Acquire reservation lock in GEM pin/unpin callbacks > drm/msm: Provide msm_gem_get_pages_locked() > drm/msm: Acquire reservation lock in GEM pin/unpin callback > drm/nouveau: Provide nouveau_bo_{pin,unpin}_locked() > drm/nouveau: Acquire reservation lock in GEM pin/unpin callbacks > drm/qxl: Provide qxl_bo_{pin,unpin}_locked() > drm/qxl: Acquire reservation lock in GEM pin/unpin callbacks > drm/gem: Acquire reservation lock in drm_gem_{pin/unpin}() > drm/fbdev-generic: Fix locking with drm_client_buffer_vmap_local() > drm/client: Pin vmap'ed GEM buffers > drm/gem-vram: Do not pin buffer objects for vmap > drm/qxl: Do not pin buffer objects for vmap The patches look good. I gave them fbtest on virtio-gpu, no problems spotted. Reviewed-by: Dmitry Osipenko Tested-by: Dmitry Osipenko # virtio-gpu -- Best regards, Dmitry