From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D0D5E26563F; Tue, 2 Sep 2025 13:22:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756819371; cv=none; b=PcZWBQMbVRe8QaUQFsLvBEd5lhTaP1VdGhQXa207xMlNXyjWxiYR2WM37B1MxS8Vn0z3lOD0SLpJo3Ftc1EiXEDwEGdyfb5xNi4zM0W6b3mJUI9b6TBu5DuwS+SdSIww0TJUc1sTeuHsLb7j/ZlVO0U6z34PKeCpvKkt1UgsPQI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756819371; c=relaxed/simple; bh=0ZoUdcZJuLVMckwdFTncIOFEDnoZvs5OGP+pOg7R3AE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Hn4dQ5NP6sSnQ0qGvseuuV8C1mZpxgrFQOkOBzWLMi6amP7PEkEfh7Cw3kV6SrhU0AiDouLdvZbUS4Ogi6tiB6lPZbdrq7JJXZPXJnWGITysTpf6wxbyWhtaAvDJNUC7Lx2xtitcuFr0rMrqa5o2KtFagoFeIcNsJhdydUb+3Ds= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=HPuOatLj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="HPuOatLj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1848C4CEF4; Tue, 2 Sep 2025 13:22:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756819371; bh=0ZoUdcZJuLVMckwdFTncIOFEDnoZvs5OGP+pOg7R3AE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HPuOatLjJWs93kUHn3xLTcSvWwwrzsq7JVb5iW3r2DxFb1p01uH8L7lDOHlTWq+ys pY4bTmrldSATelLcU0fQd0eNY1zc47f0oBUWfoFOb7pGDt1HIpzv3OsVzSSbcqavXr OB03CPEKKNp2Xb5YiGE7sRr/nFc1O/85+1f5jCHA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Igor Torrente , "Michael S. Tsirkin" , Sasha Levin Subject: [PATCH 6.16 015/142] Revert "virtio: reject shm region if length is zero" Date: Tue, 2 Sep 2025 15:18:37 +0200 Message-ID: <20250902131948.736546179@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250902131948.154194162@linuxfoundation.org> References: <20250902131948.154194162@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Igor Torrente [ Upstream commit ced17ee32a9988b8a260628e7c31a100d7dc082e ] The commit 206cc44588f7 ("virtio: reject shm region if length is zero") breaks the Virtio-gpu `host_visible` feature. As you can see in the snippet below, host_visible_region is zero because of the `kzalloc`. It's using the `vm_get_shm_region` (drivers/virtio/virtio_mmio.c:536) to read the `addr` and `len` from qemu/crosvm. ``` drivers/gpu/drm/virtio/virtgpu_kms.c 132 vgdev = drmm_kzalloc(dev, sizeof(struct virtio_gpu_device), GFP_KERNEL); [...] 177 if (virtio_get_shm_region(vgdev->vdev, &vgdev->host_visible_region, 178 VIRTIO_GPU_SHM_ID_HOST_VISIBLE)) { ``` Now it always fails. To fix, revert the offending commit. Fixes: 206cc44588f7 ("virtio: reject shm region if length is zero") Signed-off-by: Igor Torrente Message-Id: <20250807124145.81816-1-igor.torrente@collabora.com> Signed-off-by: Michael S. Tsirkin Signed-off-by: Sasha Levin --- include/linux/virtio_config.h | 2 -- 1 file changed, 2 deletions(-) diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index b3e1d30c765bc..169c7d367facb 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -329,8 +329,6 @@ static inline bool virtio_get_shm_region(struct virtio_device *vdev, struct virtio_shm_region *region, u8 id) { - if (!region->len) - return false; if (!vdev->config->get_shm_region) return false; return vdev->config->get_shm_region(vdev, region, id); -- 2.50.1