drm/amdgpu: replace iova debugfs file with iomem (v3)

This allows access to pages allocated through the driver with optional
IOMMU mapping.

v2: Fix number of bytes copied and add write method
v3: drop check for kmap return

Original-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 81 insertions, 21 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index b19a4f7a845e..28c33d711bab 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1957,38 +1957,98 @@ 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;
+
+                bytes = bytes < size ? bytes : size;
+
+                addr = dom ? iommu_iova_to_phys(dom, addr) : addr;
+
+                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;
+
+                size -= bytes;
+                *pos += bytes;
+                result += bytes;
+        }
+
+        return result;
+}
+
+static ssize_t amdgpu_iomem_write(struct file *f, const char __user *buf,
+                                 size_t size, loff_t *pos)
+{
+        struct amdgpu_device *adev = file_inode(f)->i_private;
+        struct iommu_domain *dom;
+        ssize_t result = 0;
+        int r;
 
         dom = iommu_get_domain_for_dev(adev->dev);
-        if (dom)
-                phys = iommu_iova_to_phys(dom, *pos);
-        else
-                phys = *pos;
 
-        r = copy_to_user(buf, &phys, 8);
-        if (r)
-                return -EFAULT;
+        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;
+
+                bytes = bytes < size ? bytes : size;
 
-        return 8;
+                addr = dom ? iommu_iova_to_phys(dom, addr) : addr;
+
+                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_from_user(ptr, buf, bytes);
+                kunmap(p);
+                if (r)
+                        return -EFAULT;
+
+                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,
+        .write = amdgpu_iomem_write,
         .llseek = default_llseek
 };
 
@@ -2001,7 +2061,7 @@ 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