Baolu: Thanks for your comments and your patch. Please find below our responses to each of your comments:
> What does "I/O operation won't work" exactly mean here? Do you see any > IOMMU fault message? Or, something doesn't work as expected? Yes, DMAR fault messages as following came out: [ 354.939896] DMAR: DMAR:[DMA Read] Request device [03:00.1]fault addr 1fdfe80000 [ 354.939896] DMAR:[fault reason 02] Present bit in context entry is clear > Do you mind checking this? > > index 6ecdcf8fc8c0..f62f30bc1339 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -2632,6 +2632,9 @@ static struct dmar_domain > *find_or_alloc_domain(struct device *dev, int gaw) > goto out; > } > > + if (!iommu_should_identity_map(dev, 0)) > + return si_domain; > + > /* Allocate and initialize new domain for the device */ > domain = alloc_domain(0); > if (!domain) Tried this patch, and the same DMAR fault message came out. Guess it is because of the iommu code path for hotplug devices. If a hotplug device is rescanned after removal, iommu_bus_notifier will be called as part of the notifier chains to handle BUS_NOTIFY_ADD_DEVICE event. Along the code path, intel_iommu_ops->add_device() created an iommu group for this hotplug device, but failed to create an iommu domain because of the default domain type IOMMU_DOMAIN_IDENTITY imposed by current IOMMU command line option got declined by intel_iommu_ops->domain_alloc(). In your patch, function find_or_alloc_domain() is not even in the code path of BUS_NOTIFY_ADD_DEVICE event notifier chain. Please let us know if your have more concerns and suggestions. Best Regards, James On Thu, Feb 21, 2019 at 9:35 PM Lu Baolu <baolu...@linux.intel.com> wrote: > Hi > > On 2/22/19 1:06 PM, Lu Baolu wrote: > > > Do you mind checking this? > > > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > > index 6ecdcf8fc8c0..f62f30bc1339 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -2632,6 +2632,9 @@ static struct dmar_domain > > *find_or_alloc_domain(struct device *dev, int gaw) > > goto out; > > } > > > > + if (!iommu_should_identity_map(dev, 0)) > > + return si_domain; > > + > > /* Allocate and initialize new domain for the device */ > > domain = alloc_domain(0); > > if (!domain) > > Oops! This can't be compiled. Please try below instead if you'd like to. > Sorry about it. > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 6ecdcf8fc8c0..b89f5ba6a3c8 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -174,6 +174,8 @@ static inline unsigned long virt_to_dma_pfn(void *p) > return page_to_dma_pfn(virt_to_page(p)); > } > > +static int iommu_should_identity_map(struct device *dev, int startup); > + > /* global iommu list, set NULL for ignored DMAR units */ > static struct intel_iommu **g_iommus; > > @@ -2632,6 +2634,9 @@ static struct dmar_domain > *find_or_alloc_domain(struct device *dev, int gaw) > goto out; > } > > + if (iommu_should_identity_map(dev, 0)) > + return si_domain; > + > /* Allocate and initialize new domain for the device */ > domain = alloc_domain(0); > if (!domain) > > Best regards, > Lu Baolu > > >
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