Re: [RFC 3/7] iommufd: Add iommufd_device_bind_pasid()

Yi Liu
2023-11-08T07:43:45Z

On 2023/10/10 16:19, Tian, Kevin wrote:
>> From: Liu, Yi L <yi.l.liu@intel.com>
>> Sent: Monday, October 9, 2023 4:51 PM
>>
>> +struct iommufd_device *iommufd_device_bind_pasid(struct iommufd_ctx
>> *ictx,
>> + struct device *dev,
>> + u32 pasid, u32 *id)
>> +{
>> + struct iommufd_device *idev;
>> + int rc;
>> +
>> + /*
>> + * iommufd always sets IOMMU_CACHE because we offer no way for
>> userspace
>> + * to restore cache coherency.
>> + */
>> + if (!device_iommu_capable(dev, IOMMU_CAP_CACHE_COHERENCY))
>> + return ERR_PTR(-EINVAL);
>> +
>> + /*
>> + * No iommu supports pasid-granular msi message today. Here we
>> + * just check whether the parent device can do safe interrupts.
>> + * Isolation between virtual devices within the parent device
>> + * relies on the parent driver to enforce.
>> + */
>> + if (!iommufd_selftest_is_mock_dev(dev) &&
>> + !msi_device_has_isolated_msi(dev)) {
>> + rc = iommufd_allow_unsafe_interrupts(dev);
>> + if (rc)
>> + return ERR_PTR(rc);
>> + }
>> +
>
> Only MemWr w/o pasid can be interpreted as an interrupt message
> then we need msi isolation to protect.

yes.

>
> But for SIOV all MemWr's are tagged with a pasid hence can never
> trigger an interrupt. From this angle looks this check is unnecessary.

But the interrupts out from a SIOV virtual device do not have pasid (at
least today). Seems still need a check here if we consider this bind for
a SIOV virtual device just like binding a physical device.

--
Regards,
Yi Liu