| Message ID | 20200527165617.297470-2-jonathan.derrick@intel.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | iommu/vt-d: real DMA sub-device info allocation | expand |
On 2020/5/28 0:56, Jon Derrick wrote: > Domain context mapping can encounter issues with sub-devices of a real > DMA device. A sub-device cannot have a valid context entry due to it > potentially aliasing another device's 16-bit ID. It's expected that > sub-devices of the real DMA device uses the real DMA device's requester > when context mapping. > > This is an issue when a sub-device is removed where the context entry is > cleared for all aliases. Other sub-devices are still valid, resulting in > those sub-devices being stranded without valid context entries. > > The correct approach is to use the real DMA device when programming the > context entries. The insertion path is correct because device_to_iommu() > will return the bus and devfn of the real DMA device. The removal path > needs to only operate on the real DMA device, otherwise the entire > context entry would be cleared for all sub-devices of the real DMA > device. > > This patch also adds a helper to determine if a struct device is a > sub-device of a real DMA device. > > Signed-off-by: Jon Derrick <jonathan.derrick@intel.com> Fixes: 2b0140c69637e ("iommu/vt-d: Use pci_real_dma_dev() for mapping") Acked-by: Lu Baolu <baolu.lu@linux.intel.com> Best regards, baolu
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index ff5a30a..1ff45b2 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -2500,6 +2500,12 @@ static int domain_setup_first_level(struct intel_iommu *iommu, flags); } +static bool dev_is_real_dma_subdevice(struct device *dev) +{ + return dev && dev_is_pci(dev) && + pci_real_dma_dev(to_pci_dev(dev)) != to_pci_dev(dev); +} + static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu, int bus, int devfn, struct device *dev, @@ -4975,7 +4981,8 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info) PASID_RID2PASID, false); iommu_disable_dev_iotlb(info); - domain_context_clear(iommu, info->dev); + if (!dev_is_real_dma_subdevice(info->dev)) + domain_context_clear(iommu, info->dev); intel_pasid_free_table(info->dev); }
Domain context mapping can encounter issues with sub-devices of a real DMA device. A sub-device cannot have a valid context entry due to it potentially aliasing another device's 16-bit ID. It's expected that sub-devices of the real DMA device uses the real DMA device's requester when context mapping. This is an issue when a sub-device is removed where the context entry is cleared for all aliases. Other sub-devices are still valid, resulting in those sub-devices being stranded without valid context entries. The correct approach is to use the real DMA device when programming the context entries. The insertion path is correct because device_to_iommu() will return the bus and devfn of the real DMA device. The removal path needs to only operate on the real DMA device, otherwise the entire context entry would be cleared for all sub-devices of the real DMA device. This patch also adds a helper to determine if a struct device is a sub-device of a real DMA device. Signed-off-by: Jon Derrick <jonathan.derrick@intel.com> --- drivers/iommu/intel-iommu.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)