drm/amd/amdgpu: add support for iova_to_phys to replace TTM trace (v5)

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

(v2): Add domain to iova debugfs
(v3): Add true read/write methods to access system memory of pages
      mapped to the device
(v4): Move get_domain call out of loop and return on error
(v5): Just use kmap/kunmap

1 files changed, 99 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 50d20903de4f..c7f8e081a772 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -43,6 +43,7 @@
 #include <linux/swap.h>
 #include <linux/pagemap.h>
 #include <linux/debugfs.h>
+#include <linux/iommu.h>
 #include "amdgpu.h"
 #include "amdgpu_trace.h"
 #include "bif/bif_4_1_d.h"
@@ -1809,7 +1810,104 @@ 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)
+{
+        struct amdgpu_device *adev = file_inode(f)->i_private;
+        ssize_t result, n;
+        int r;
+        uint64_t phys;
+        void *ptr;
+        struct iommu_domain *dom;
+
+        dom = iommu_get_domain_for_dev(adev->dev);
+        if (!dom)
+                return -EFAULT;
+
+        result = 0;
+        while (size) {
+                // get physical address and map
+                phys = iommu_iova_to_phys(dom, *pos);
+
+                // copy upto one page
+                if (size > PAGE_SIZE)
+                        n = PAGE_SIZE;
+                else
+                        n = size;
+
+                // to end of the page
+                if (((*pos & (PAGE_SIZE - 1)) + n) >= PAGE_SIZE)
+                        n = PAGE_SIZE - (*pos & (PAGE_SIZE - 1));
+
+                ptr = kmap(pfn_to_page(PFN_DOWN(phys)));
+                if (!ptr)
+                        return -EFAULT;
+
+                r = copy_to_user(buf, ptr, n);
+                kunmap(pfn_to_page(PFN_DOWN(phys)));
+                if (r)
+                        return -EFAULT;
+
+                *pos += n;
+                size -= n;
+                result += n;
+        }
+
+        return result;
+}
+
+static ssize_t amdgpu_iova_to_phys_write(struct file *f, const char __user *buf,
+                                   size_t size, loff_t *pos)
+{
+        struct amdgpu_device *adev = file_inode(f)->i_private;
+        ssize_t result, n;
+        int r;
+        uint64_t phys;
+        void *ptr;
+        struct iommu_domain *dom;
+
+        dom = iommu_get_domain_for_dev(adev->dev);
+        if (!dom)
+                return -EFAULT;
+
+        result = 0;
+        while (size) {
+                // get physical address and map
+                phys = iommu_iova_to_phys(dom, *pos);
 
+                // copy upto one page
+                if (size > PAGE_SIZE)
+                        n = PAGE_SIZE;
+                else
+                        n = size;
+
+                // to end of the page
+                if (((*pos & (PAGE_SIZE - 1)) + n) >= PAGE_SIZE)
+                        n = PAGE_SIZE - (*pos & (PAGE_SIZE - 1));
+
+                ptr = kmap(pfn_to_page(PFN_DOWN(phys)));
+                if (!ptr)
+                        return -EFAULT;
+
+                r = copy_from_user(ptr, buf, n);
+                kunmap(pfn_to_page(PFN_DOWN(phys)));
+                if (r)
+                        return -EFAULT;
+
+                *pos += n;
+                size -= n;
+                result += n;
+        }
+
+        return result;
+}
+
+static const struct file_operations amdgpu_ttm_iova_fops = {
+        .owner = THIS_MODULE,
+        .read = amdgpu_iova_to_phys_read,
+        .write = amdgpu_iova_to_phys_write,
+        .llseek = default_llseek
+};
 
 static const struct {
         char *name;
@@ -1820,6 +1918,7 @@ 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 },
 };
 
 #endif