Messages in this thread |  | | Subject | Re: [PATCH] iommu/intel-iommu: set as DUMMY_DEVICE_DOMAIN_INFO if no IOMMU | From | Lu Baolu <> | Date | Wed, 5 Feb 2020 09:28:09 +0800 |
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Hi,
On 2020/2/4 17:25, Jian-Hong Pan wrote: > Lu Baolu <baolu.lu@linux.intel.com> 於 2020年2月4日 週二 下午2:11寫道: >> >> Hi, >> >> On 2020/2/3 17:10, Jian-Hong Pan wrote: >>> If the device has no IOMMU, it still invokes iommu_need_mapping during >>> intel_alloc_coherent. However, iommu_need_mapping can only check the >>> device is DUMMY_DEVICE_DOMAIN_INFO or not. This patch marks the device >>> is a DUMMY_DEVICE_DOMAIN_INFO if the device has no IOMMU. >>> >>> Signed-off-by: Jian-Hong Pan <jian-hong@endlessm.com> >>> --- >>> drivers/iommu/intel-iommu.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c >>> index 35a4a3abedc6..878bc986a015 100644 >>> --- a/drivers/iommu/intel-iommu.c >>> +++ b/drivers/iommu/intel-iommu.c >>> @@ -5612,8 +5612,10 @@ static int intel_iommu_add_device(struct device *dev) >>> int ret; >>> >>> iommu = device_to_iommu(dev, &bus, &devfn); >>> - if (!iommu) >>> + if (!iommu) { >>> + dev->archdata.iommu = DUMMY_DEVICE_DOMAIN_INFO; >> >> Is this a DMA capable device? > > Do you mean is the device in DMA Remapping table? > Dump DMAR from ACPI table. The device is not in the table. > So, it does not support DMAR, Intel IOMMU. > > Or, should device_to_iommu be invoked in iommu_need_mapping to check > IOMMU feature again? >
Normally intel_iommu_add_device() should only be called for PCI devices and APCI name space devices (reported in ACPI/DMAR table). In both cases, device_to_iommu() should always return a corresponding iommu. I just tried to understand why it failed for your case.
Best regards, baolu
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