linux-kernel - [PATCH] iommu/vt-d: Don't reject nvme host due to scope mismatch

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Message-Id: <1576825674-18022-1-git-send-email-jimyan@baidu.com>
Date:   Fri, 20 Dec 2019 15:07:54 +0800
From:   jimyan <jimyan@...du.com>
To:     joro@...tes.org
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        jimyan@...du.com
Subject: [PATCH] iommu/vt-d: Don't reject nvme host due to scope mismatch

On a system with an Intel PCIe port configured as a nvme host device, iommu
initialization fails with

    DMAR: Device scope type does not match for 0000:80:00.0

This is because the DMAR table reports this device as having scope 2
(ACPI_DMAR_SCOPE_TYPE_BRIDGE):

but the device has a type 0 PCI header:
80:00.0 Class 0600: Device 8086:2020 (rev 06)
00: 86 80 20 20 47 05 10 00 06 00 00 06 10 00 00 00
10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 86 80 00 00
30: 00 00 00 00 90 00 00 00 00 00 00 00 00 01 00 00

VT-d works perfectly on this system, so there's no reason to bail out
on initialization due to this apparent scope mismatch. Add the class
0x600 ("PCI_CLASS_BRIDGE_HOST") as a heuristic for allowing DMAR
initialization for non-bridge PCI devices listed with scope bridge.

Signed-off-by: jimyan <jimyan@...du.com>
---
 drivers/iommu/dmar.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index eecd6a421667..9faf2f0e0237 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -244,6 +244,7 @@ int dmar_insert_dev_scope(struct dmar_pci_notify_info *info,
 		     info->dev->hdr_type != PCI_HEADER_TYPE_NORMAL) ||
 		    (scope->entry_type == ACPI_DMAR_SCOPE_TYPE_BRIDGE &&
 		     (info->dev->hdr_type == PCI_HEADER_TYPE_NORMAL &&
+			  info->dev->class >> 8 != PCI_CLASS_BRIDGE_HOST &&
 		      info->dev->class >> 8 != PCI_CLASS_BRIDGE_OTHER))) {
 			pr_warn("Device scope type does not match for %s\n",
 				pci_name(info->dev));
-- 
2.11.0