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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F160C3527A for ; Tue, 5 Apr 2022 12:03:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244942AbiDEMCB (ORCPT ); Tue, 5 Apr 2022 08:02:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243058AbiDEItt (ORCPT ); Tue, 5 Apr 2022 04:49:49 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 112859A981; Tue, 5 Apr 2022 01:38:13 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DE9D7B81C14; Tue, 5 Apr 2022 08:37:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34611C385AC; Tue, 5 Apr 2022 08:37:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649147869; bh=Z7Iazl7/bScHJMF92CdAuqvWcfVT7b/g3XtcPxhvL6M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S5FU2F/qchRc1AHfUc+KyAtindXZSi/5NYJ9Hfn9CWr1XazsWzi74HJoQ7xS1sDCU lMoedHX2lOcrPaFY/bnzU0lws/KlkQYNU621GYUdZmgkFpumYzoGU/fely7EKlNva8 M8T5c9yxXlDdZ7o+xgFu5i2TxVfxJ4B/B4ZYO0H8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Zimmermann , Zack Rusin , Javier Martinez Canillas , Hans de Goede Subject: [PATCH 5.16 0150/1017] fbdev: Hot-unplug firmware fb devices on forced removal Date: Tue, 5 Apr 2022 09:17:43 +0200 Message-Id: <20220405070358.660297344@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Zimmermann commit 27599aacbaefcbf2af7b06b0029459bbf682000d upstream. Hot-unplug all firmware-framebuffer devices as part of removing them via remove_conflicting_framebuffers() et al. Releases all memory regions to be acquired by native drivers. Firmware, such as EFI, install a framebuffer while posting the computer. After removing the firmware-framebuffer device from fbdev, a native driver takes over the hardware and the firmware framebuffer becomes invalid. Firmware-framebuffer drivers, specifically simplefb, don't release their device from Linux' device hierarchy. It still owns the firmware framebuffer and blocks the native drivers from loading. This has been observed in the vmwgfx driver. [1] Initiating a device removal (i.e., hot unplug) as part of remove_conflicting_framebuffers() removes the underlying device and returns the memory range to the system. [1] https://lore.kernel.org/dri-devel/20220117180359.18114-1-zack@kde.org/ v2: * rename variable 'dev' to 'device' (Javier) Signed-off-by: Thomas Zimmermann Reported-by: Zack Rusin Reviewed-by: Javier Martinez Canillas Reviewed-by: Zack Rusin Reviewed-by: Hans de Goede CC: stable@vger.kernel.org # v5.11+ Link: https://patchwork.freedesktop.org/patch/msgid/20220125091222.21457-2-tzimmermann@suse.de Signed-off-by: Greg Kroah-Hartman --- drivers/video/fbdev/core/fbmem.c | 29 ++++++++++++++++++++++++++--- include/linux/fb.h | 1 + 2 files changed, 27 insertions(+), 3 deletions(-) --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -1557,18 +1558,36 @@ static void do_remove_conflicting_frameb /* check all firmware fbs and kick off if the base addr overlaps */ for_each_registered_fb(i) { struct apertures_struct *gen_aper; + struct device *device; if (!(registered_fb[i]->flags & FBINFO_MISC_FIRMWARE)) continue; gen_aper = registered_fb[i]->apertures; + device = registered_fb[i]->device; if (fb_do_apertures_overlap(gen_aper, a) || (primary && gen_aper && gen_aper->count && gen_aper->ranges[0].base == VGA_FB_PHYS)) { printk(KERN_INFO "fb%d: switching to %s from %s\n", i, name, registered_fb[i]->fix.id); - do_unregister_framebuffer(registered_fb[i]); + + /* + * If we kick-out a firmware driver, we also want to remove + * the underlying platform device, such as simple-framebuffer, + * VESA, EFI, etc. A native driver will then be able to + * allocate the memory range. + * + * If it's not a platform device, at least print a warning. A + * fix would add code to remove the device from the system. + */ + if (dev_is_platform(device)) { + registered_fb[i]->forced_out = true; + platform_device_unregister(to_platform_device(device)); + } else { + pr_warn("fb%d: cannot remove device\n", i); + do_unregister_framebuffer(registered_fb[i]); + } } } } @@ -1898,9 +1917,13 @@ EXPORT_SYMBOL(register_framebuffer); void unregister_framebuffer(struct fb_info *fb_info) { - mutex_lock(®istration_lock); + bool forced_out = fb_info->forced_out; + + if (!forced_out) + mutex_lock(®istration_lock); do_unregister_framebuffer(fb_info); - mutex_unlock(®istration_lock); + if (!forced_out) + mutex_unlock(®istration_lock); } EXPORT_SYMBOL(unregister_framebuffer); --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -502,6 +502,7 @@ struct fb_info { } *apertures; bool skip_vt_switch; /* no VT switch on suspend/resume required */ + bool forced_out; /* set when being removed by another driver */ }; static inline struct apertures_struct *alloc_apertures(unsigned int max_num) {