Re: [PATCH 5/5] drm/amdgpu: replace iova debugfs file with iomem

["StDenis, Tom" <Tom.StDenis@xxxxxxx>]

I haven't tried the patch but just like to point out this breaks umr :-)  I'll have to craft something on Monday to support this and iova in parallel until the iova kernels are realistically EOL'ed.

On the other hand I support this idea since it eliminates the need for an fmem hack.  So much appreciated.

Cheers,
Tom

________________________________________
From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> on behalf of Christian König <ckoenig.leichtzumerken@xxxxxxxxx>
Sent: Friday, February 2, 2018 14:09
To: amd-gfx@xxxxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx
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@xxxxxxx>
---
 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

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