Re: [PATCH 4/5] iommu/vt-d: Disallow SVA if devices don't support 64-bit address

From: Robin Murphy
Date: Tue Jul 20 2021 - 05:27:34 EST

On 2021-07-20 02:38, Lu Baolu wrote:
When the device and CPU share an address space (such as SVA), the device
must support the same addressing capability as the CPU. The CPU does not
consider the addressing ability of any device when managing the page table
of a process, so the device must have enough addressing ability to bind
the page table of the process.

Signed-off-by: Lu Baolu <>
drivers/iommu/intel/iommu.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index f45c80ce2381..f3cca1dd384d 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -5372,6 +5372,9 @@ static int intel_iommu_enable_sva(struct device *dev)
if (!(iommu->flags & VTD_FLAG_SVM_CAPABLE))
return -ENODEV;
+ if (!dev->dma_mask || *dev->dma_mask != DMA_BIT_MASK(64))

Careful - VFIO doesn't set DMA masks (since it doesn't use the DMA API), so this appears to be relying on another driver having bound previously, otherwise the mask would still be the default 32-bit one from pci_setup_device(). I'm not sure that's an entirely robust assumption.


+ return -ENODEV;
if (intel_iommu_enable_pasid(iommu, dev))
return -ENODEV;