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 940028481 for ; Fri, 10 Mar 2023 14:12:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17E67C4339C; Fri, 10 Mar 2023 14:12:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678457541; bh=NqyLywQdr+GjqxAN5/Ok/tyfg5uViJIHxKLt5nmQYBs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=boCwXBHrprpq9ZfXSQi3R/3MAScFHBQ5eKnfPbzKTr8xbEfXp9md9tWs7KTQrwA6L RFS8vHDuD3UKB/O6yylWL/bYhS8U8bL/KpiSdI6OlFdaEqJMI+H8O3/cwBEAEYF++Y 0S0U4P5B9Cg3hq5+SVlG0f7pRj/7y7T41uUShxoM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lu Baolu , Matt Fagnani , Vasant Hegde , Jason Gunthorpe , Joerg Roedel , Sasha Levin Subject: [PATCH 6.1 173/200] iommu: Attach device group to old domain in error path Date: Fri, 10 Mar 2023 14:39:40 +0100 Message-Id: <20230310133722.414436375@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133717.050159289@linuxfoundation.org> References: <20230310133717.050159289@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Vasant Hegde [ Upstream commit 2cc73c5712f97de98c38c2fafc1f288354a9f3c3 ] iommu_attach_group() attaches all devices in a group to domain and then sets group domain (group->domain). Current code (__iommu_attach_group()) does not handle error path. This creates problem as devices to domain attachment is in inconsistent state. Flow: - During boot iommu attach devices to default domain - Later some device driver (like amd/iommu_v2 or vfio) tries to attach device to new domain. - In iommu_attach_group() path we detach device from current domain. Then it tries to attach devices to new domain. - If it fails to attach device to new domain then device to domain link is broken. - iommu_attach_group() returns error. - At this stage iommu_attach_group() caller thinks, attaching device to new domain failed and devices are still attached to old domain. - But in reality device to old domain link is broken. It will result in all sort of failures (like IO page fault) later. To recover from this situation, we need to attach all devices back to the old domain. Also log warning if it fails attach device back to old domain. Suggested-by: Lu Baolu Reported-by: Matt Fagnani Signed-off-by: Vasant Hegde Reviewed-by: Jason Gunthorpe Tested-by: Matt Fagnani Link: https://lore.kernel.org/r/20230215052642.6016-1-vasant.hegde@amd.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=216865 Link: https://lore.kernel.org/lkml/15d0f9ff-2a56-b3e9-5b45-e6b23300ae3b@leemhuis.info/ Signed-off-by: Joerg Roedel Signed-off-by: Sasha Levin --- drivers/iommu/iommu.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index fd8c8aeb3c504..bfb2f163c6914 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -2089,8 +2089,22 @@ static int __iommu_attach_group(struct iommu_domain *domain, ret = __iommu_group_for_each_dev(group, domain, iommu_group_do_attach_device); - if (ret == 0) + if (ret == 0) { group->domain = domain; + } else { + /* + * To recover from the case when certain device within the + * group fails to attach to the new domain, we need force + * attaching all devices back to the old domain. The old + * domain is compatible for all devices in the group, + * hence the iommu driver should always return success. + */ + struct iommu_domain *old_domain = group->domain; + + group->domain = NULL; + WARN(__iommu_group_set_domain(group, old_domain), + "iommu driver failed to attach a compatible domain"); + } return ret; } -- 2.39.2