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Subject答复: 答复: [PATCH] iommu/vt-d: Don't rej ect nvme host due to scope mismatch
Date
> -----邮件原件-----
> 发件人: Lu Baolu [mailto:baolu.lu@linux.intel.com]
> 发送时间: 2019年12月23日 21:05
> 收件人: Jim,Yan <jimyan@baidu.com>; Jerry Snitselaar <jsnitsel@redhat.com>
> 抄送: iommu@lists.linux-foundation.org; linux-kernel@vger.kernel.org
> 主题: Re: 答复: [PATCH] iommu/vt-d: Don't reject nvme host due to scope
> mismatch
>
> Hi,
>
> On 2019/12/23 15:59, Jim,Yan wrote:
> >> -----邮件原件-----
> >> 发件人: Jerry Snitselaar [mailto:jsnitsel@redhat.com]
> >> 发送时间: 2019年12月20日 17:23
> >> 收件人: Jim,Yan <jimyan@baidu.com>
> >> 抄送: joro@8bytes.org; iommu@lists.linux-foundation.org;
> >> linux-kernel@vger.kernel.org
> >> 主题: Re: [PATCH] iommu/vt-d: Don't reject nvme host due to scope
> >> mismatch
> >>
> >> On Fri Dec 20 19, jimyan wrote:
> >>> 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):
> >>>
> >>
> >> Isn't that a problem to be fixed in the DMAR table then?
> >>
> >>> 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@baidu.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
> >>>
> >>> _______________________________________________
> >>> iommu mailing list
> >>> iommu@lists.linux-foundation.org
> >>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
> >>>
> > Actually this patch is similar to the commit: ffb2d1eb88c3("iommu/vt-d: Don't
> reject NTB devices due to scope mismatch"). Besides, modifying DMAR table
> need OEM update BIOS. It is hard to implement.
> >
>
> For both cases, a quirk flag seems to be more reasonable, so that unrelated
> devices will not be impacted.
>
> Best regards,
> baolu

Hi Baolu,
Thanks for your advice. And I modify the patch as follow.

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
0x06 ("PCI_BASE_CLASS_BRIDGE") as a heuristic for allowing DMAR
initialization for non-bridge PCI devices listed with scope bridge.

Signed-off-by: jimyan <jimyan@baidu.com>

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index eecd6a421667..50c92eb23ee4 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -244,7 +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_OTHER))) {
+ info->dev->class >> 16 != PCI_BASE_CLASS_BRIDGE))) {
pr_warn("Device scope type does not match for %s\n",
pci_name(info->dev));
return -EINVAL;

Jim

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