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 177758F7B for ; Fri, 3 Mar 2023 21:43:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1A73C433A7; Fri, 3 Mar 2023 21:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677879790; bh=GdIekXKTgJ/2knGO1EfBSkJFGT7Ks5ynxAYuXSzW8As=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rMZpws2Y6pofmW9n6yU1ZXPInBP+/FwoWKBRDcWhMyWK84saC30diIsOsbsWwi6GR kWK7sbMgZfWCvZ5333ShCOxqjW9Vhf+IeBHC4eIaITY/zkyZ46Jmt6NCrTNuHmdacl uNml7BzJM34dxCfxZokoQLuRtmE5sUm2Otu2oW5fPMdEC6l6pv6PUuRVUDZx1aCdOb wwqKuC+UpOq/8synMLxj8Wglbn2leoK4HuR3dM6kk2hnaut9E2OWoYw5lSjC/oDyYf F8H4NG9XR81Xl1jt028OmrF9Fef34VB6SJlyrBgaT4Dv4vun1+exiAP+Knu7scAgym zcsO3TEbXECDw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vasant Hegde , Lu Baolu , Matt Fagnani , Jason Gunthorpe , Joerg Roedel , Sasha Levin , joro@8bytes.org, will@kernel.org, iommu@lists.linux.dev Subject: [PATCH AUTOSEL 6.2 62/64] iommu: Attach device group to old domain in error path Date: Fri, 3 Mar 2023 16:41:04 -0500 Message-Id: <20230303214106.1446460-62-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230303214106.1446460-1-sashal@kernel.org> References: <20230303214106.1446460-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 54e1306a99a47..f91b5b1a39e3b 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -2126,8 +2126,22 @@ 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