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

[Lu Baolu]

Hi,

On 12/12/19 12:35 AM, Jerry Snitselaar wrote:
> 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?

No. iommu_map/unmap() should not be called for default identity domain.

        if (unlikely(!(domain->type & __IOMMU_DOMAIN_PAGING)))
                return -EINVAL;

Best regards,
baolu

> > 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,
> > ÂÂÂÂint prot = 0;
> > ÂÂÂÂint ret;
> >
> > -ÂÂÂ if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN)
> > -ÂÂÂÂÂÂÂ return -EINVAL;
> > -
> > ÂÂÂÂif (iommu_prot & IOMMU_READ)
> > ÂÂÂÂÂÂÂ prot |= DMA_PTE_READ;
> > ÂÂÂÂif (iommu_prot & IOMMU_WRITE)
> > @@ -5523,8 +5520,6 @@ static size_t intel_iommu_unmap(struct 
> > iommu_domain *domain,
> > ÂÂÂÂ/* Cope with horrid API which requires us to unmap more than the
> > ÂÂÂÂÂÂ size argument if it happens to be a large-page mapping. */
> > ÂÂÂÂBUG_ON(!pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, &level));
> > -ÂÂÂ if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN)
> > -ÂÂÂÂÂÂÂ return 0;
> >
> > ÂÂÂÂif (size < VTD_PAGE_SIZE << level_to_offset_bits(level))
> > ÂÂÂÂÂÂÂ 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,
> > ÂÂÂÂint level = 0;
> > ÂÂÂÂu64 phys = 0;
> >
> > -ÂÂÂ if (dmar_domain->flags & DOMAIN_FLAG_LOSE_CHILDREN)
> > -ÂÂÂÂÂÂÂ return 0;
> > -
> > ÂÂÂÂpte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, &level);
> > ÂÂÂÂif (pte)
> > ÂÂÂÂÂÂÂ phys = dma_pte_addr(pte);
> > --
> > 2.17.1