Messages in this thread | | | Subject | Re: [PATCH 4/5] iommu/vt-d: Disallow SVA if devices don't support 64-bit address | From | Lu Baolu <> | Date | Wed, 21 Jul 2021 09:50:49 +0800 |
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Hi Robin,
Thanks a lot for reviewing my patch!
On 7/20/21 5:27 PM, Robin Murphy wrote: > 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 <baolu.lu@linux.intel.com> >> --- >> 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),
SVA doesn't work through the VFIO framework.
> so this appears to be relying on another driver having bound previously,
Yes. You are right.
> 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.
Currently SVA implementation always requires a native kernel driver. The assumption is that the drivers should check and set 64-bit addressing capability before calling iommu_sva_xxx() APIs.
> > Robin. > >> + return -ENODEV; >> + >> if (intel_iommu_enable_pasid(iommu, dev)) >> return -ENODEV; >>
Best regards, baolu
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