Messages in this thread | | | Subject | Re: [PATCH] iommu/dma: limit the IOVA allocated to dma-ranges region | From | Robin Murphy <> | Date | Fri, 1 Sep 2017 10:43:05 +0100 |
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On 01/09/17 10:26, Joerg Roedel wrote: > Adding Robin for review. > > On Thu, Aug 31, 2017 at 03:08:21PM -0700, Krishna Reddy wrote: >> Limit the IOVA allocated to dma-ranges specified for the device. >> This is necessary to ensure that IOVA allocated is addressable >> by device.
Why? IOVA allocation is already constrained as much as it should be - if the device's DMA mask is wrong that's another problem, and this isn't the right place to fix it.
dma_32bit_pfn means nothing more than an internal detail of IOVA allocator caching, which is subject to change[1]. As-is, on some platforms this patch will effectively force all allocations to fail already.
Robin.
[1]:https://www.mail-archive.com/iommu@lists.linux-foundation.org/msg19694.html >> Signed-off-by: Krishna Reddy <vdumpa@nvidia.com> >> --- >> drivers/iommu/dma-iommu.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c >> index 9d1cebe7f6cb..e8a8320b571b 100644 >> --- a/drivers/iommu/dma-iommu.c >> +++ b/drivers/iommu/dma-iommu.c >> @@ -364,6 +364,7 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain, >> struct iommu_dma_cookie *cookie = domain->iova_cookie; >> struct iova_domain *iovad = &cookie->iovad; >> unsigned long shift, iova_len, iova = 0; >> + dma_addr_t dma_end_addr; >> >> if (cookie->type == IOMMU_DMA_MSI_COOKIE) { >> cookie->msi_iova += size; >> @@ -381,6 +382,10 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain, >> if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1))) >> iova_len = roundup_pow_of_two(iova_len); >> >> + /* Limit IOVA allocated to device addressable dma-ranges region. */ >> + dma_end_addr = (dma_addr_t)iovad->dma_32bit_pfn << shift; >> + dma_limit = dma_limit > dma_end_addr ? dma_end_addr : dma_limit; > > This looks like a good use-case for min(). > >> + >> if (domain->geometry.force_aperture) >> dma_limit = min(dma_limit, domain->geometry.aperture_end); >> >> -- >> 2.1.4
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