Re: [PATCH 1/1] iommu/vt-d: Fix dmar pte read access not set error

[Jerry Snitselaar]

On Wed Dec 11 19, Lu Baolu wrote:
> If the default DMA domain of a group doesn't fit a device, it
> will still sit in the group but use a private identity domain.
> When map/unmap/iova_to_phys come through iommu API, the driver
> should still serve them, otherwise, other devices in the same
> group will be impacted. Since identity domain has been mapped
> with the whole available memory space and RMRRs, we don't need
> to worry about the impact on it.

Does this pose any potential issues with the reverse case where the
group has a default identity domain, and the first device fits that,
but a later device in the group needs dma and gets a private dma
domain?

> Link: https://www.spinics.net/lists/iommu/msg40416.html
> Cc: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
> Reported-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
> Fixes: 942067f1b6b97 ("iommu/vt-d: Identify default domains replaced with private")
> Cc: stable@xxxxxxxxxxxxxxx # v5.3+
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> ---
> drivers/iommu/intel-iommu.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 0c8d81f56a30..b73bebea9148 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -5478,9 +5478,6 @@ static int intel_iommu_map(struct iommu_domain *domain,
> 	int prot = 0;
> 	int ret;
>
> -	if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN)
> -		return -EINVAL;
> -
> 	if (iommu_prot & IOMMU_READ)
> 		prot |= DMA_PTE_READ;
> 	if (iommu_prot & IOMMU_WRITE)
> @@ -5523,8 +5520,6 @@ static size_t intel_iommu_unmap(struct iommu_domain *domain,
> 	/* Cope with horrid API which requires us to unmap more than the
> 	   size argument if it happens to be a large-page mapping. */
> 	BUG_ON(!pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, &level));
> -	if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN)
> -		return 0;
>
> 	if (size < VTD_PAGE_SIZE << level_to_offset_bits(level))
> 		size = VTD_PAGE_SIZE << level_to_offset_bits(level);
> @@ -5556,9 +5551,6 @@ static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain,
> 	int level = 0;
> 	u64 phys = 0;
>
> -	if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN)
> -		return 0;
> -
> 	pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, &level);
> 	if (pte)
> 		phys = dma_pte_addr(pte);
> --
> 2.17.1