Another thing that occurred to me is this will break write access to GPU bound memory. Previously we relied on iova to translate the address and then /dev/mem or /dev/fmem to read/write it. But since this is literally a read only method obviously there's no write support. Tom On 04/02/18 09:56 PM, He, Roger wrote: > Patch1 & 2 & 4, Reviewed-by: Roger He <Hongbo.He at amd.com> > Patch 5: Acked-by: Roger He <Hongbo.He at amd.com> > > -----Original Message----- > From: dri-devel [mailto:dri-devel-bounces at lists.freedesktop.org] On Behalf Of Christian K?nig > Sent: Saturday, February 03, 2018 3:10 AM > To: amd-gfx at lists.freedesktop.org; dri-devel at lists.freedesktop.org > Subject: [PATCH 5/5] drm/amdgpu: replace iova debugfs file with iomem > > This allows access to pages allocated through the driver with optional IOMMU mapping. > > Signed-off-by: Christian König <christian.koenig at amd.com> > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 57 ++++++++++++++++++++------------- > 1 file changed, 35 insertions(+), 22 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > index 648c449aaa79..795ceaeb82d5 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > @@ -1929,38 +1929,51 @@ static const struct file_operations amdgpu_ttm_gtt_fops = { > > #endif > > -static ssize_t amdgpu_iova_to_phys_read(struct file *f, char __user *buf, > - size_t size, loff_t *pos) > +static ssize_t amdgpu_iomem_read(struct file *f, char __user *buf, > + size_t size, loff_t *pos) > { > struct amdgpu_device *adev = file_inode(f)->i_private; > - int r; > - uint64_t phys; > struct iommu_domain *dom; > + ssize_t result = 0; > + int r; > > - // always return 8 bytes > - if (size != 8) > - return -EINVAL; > + dom = iommu_get_domain_for_dev(adev->dev); > > - // only accept page addresses > - if (*pos & 0xFFF) > - return -EINVAL; > + while (size) { > + phys_addr_t addr = *pos & PAGE_MASK; > + loff_t off = *pos & ~PAGE_MASK; > + size_t bytes = PAGE_SIZE - off; > + unsigned long pfn; > + struct page *p; > + void *ptr; > > - dom = iommu_get_domain_for_dev(adev->dev); > - if (dom) > - phys = iommu_iova_to_phys(dom, *pos); > - else > - phys = *pos; > + addr = dom ? iommu_iova_to_phys(dom, addr) : addr; > > - r = copy_to_user(buf, &phys, 8); > - if (r) > - return -EFAULT; > + pfn = addr >> PAGE_SHIFT; > + if (!pfn_valid(pfn)) > + return -EPERM; > + > + p = pfn_to_page(pfn); > + if (p->mapping != adev->mman.bdev.dev_mapping) > + return -EPERM; > + > + ptr = kmap(p); > + r = copy_to_user(buf, ptr, bytes); > + kunmap(p); > + if (r) > + return -EFAULT; > > - return 8; > + size -= bytes; > + *pos += bytes; > + result += bytes; > + } > + > + return result; > } > > -static const struct file_operations amdgpu_ttm_iova_fops = { > +static const struct file_operations amdgpu_ttm_iomem_fops = { > .owner = THIS_MODULE, > - .read = amdgpu_iova_to_phys_read, > + .read = amdgpu_iomem_read, > .llseek = default_llseek > }; > > @@ -1973,7 +1986,7 @@ static const struct { #ifdef CONFIG_DRM_AMDGPU_GART_DEBUGFS > { "amdgpu_gtt", &amdgpu_ttm_gtt_fops, TTM_PL_TT }, #endif > - { "amdgpu_iova", &amdgpu_ttm_iova_fops, TTM_PL_SYSTEM }, > + { "amdgpu_iomem", &amdgpu_ttm_iomem_fops, TTM_PL_SYSTEM }, > }; > > #endif > -- > 2.14.1 > > _______________________________________________ > dri-devel mailing list > dri-devel at lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel > _______________________________________________ > amd-gfx mailing list > amd-gfx at lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx >
