On 12/5/2025 4:04 PM, Lazar, Lijo wrote:


On 12/5/2025 12:20 PM, Yo-Jung Leo Lin (AMD) wrote:
Add a uma/ directory containing two sysfs files as interfaces to
inspect or change UMA carveout size. These files are:

- uma/carveout_options: a read-only file listing all the available
   UMA allocation options and their index.

- uma/carveout: a file that is both readable and writable. On read,
   it shows the index of the current setting. Writing a valid index
   into this file allows users to change the UMA carveout size to that
   option on the next boot.

Co-developed-by: Mario Limonciello (AMD) <[email protected]>
Signed-off-by: Mario Limonciello (AMD) <[email protected]>
Reviewed-by: Alex Deucher <[email protected]>
Signed-off-by: Yo-Jung Leo Lin (AMD) <[email protected]>
---
  drivers/gpu/drm/amd/amdgpu/amdgpu.h        |   4 +
  drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c   |   7 ++
  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 138 +++++++++++++++++++ ++++++++++
  3 files changed, 149 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/ amd/amdgpu/amdgpu.h
index 6bf626a51dfc..177376ff5811 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1846,4 +1846,8 @@ void amdgpu_device_set_uid(struct amdgpu_uid *uid_info,
                 uint64_t uid);
  uint64_t amdgpu_device_get_uid(struct amdgpu_uid *uid_info,
                     enum amdgpu_uid_type type, uint8_t inst);
+
+int amdgpu_acpi_uma_option_init(struct amdgpu_device *adev);
+void amdgpu_acpi_uma_option_fini(struct amdgpu_device *adev);
+
  #endif
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c b/drivers/gpu/ drm/amd/amdgpu/amdgpu_acpi.c
index bdafcde51107..b2779fc2f712 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
@@ -1288,6 +1288,12 @@ static int amdgpu_acpi_event(struct notifier_block *nb,
  int amdgpu_acpi_init(struct amdgpu_device *adev)
  {
      struct amdgpu_atif *atif = &amdgpu_acpi_priv.atif;
+    int rc;
+
+    rc = amdgpu_acpi_uma_option_init(adev);
+
+    if (rc)
+        drm_dbg(adev_to_drm(adev), "Not creating uma carveout interfaces: %d", rc);
      if (atif->notifications.brightness_change) {
          if (adev->dc_enabled) {
@@ -1340,6 +1346,7 @@ void amdgpu_acpi_get_backlight_caps(struct amdgpu_dm_backlight_caps *caps)
  void amdgpu_acpi_fini(struct amdgpu_device *adev)
  {
      unregister_acpi_notifier(&adev->acpi_nb);
+    amdgpu_acpi_uma_option_fini(adev);
  }
  /**
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/ drm/amd/amdgpu/amdgpu_device.c
index a7594ae44b20..979298d9c213 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -36,6 +36,7 @@
  #include <linux/pci.h>
  #include <linux/pci-p2pdma.h>
  #include <linux/apple-gmux.h>
+#include <linux/nospec.h>
  #include <drm/drm_atomic_helper.h>
  #include <drm/drm_client_event.h>
@@ -7835,3 +7836,140 @@ u64 amdgpu_device_get_uid(struct amdgpu_uid *uid_info,
      return uid_info->uid[type][inst];
  }
+
+static ssize_t carveout_options_show(struct device *dev,
+                     struct device_attribute *attr,
+                     char *buf)
+{
+    struct drm_device *ddev = dev_get_drvdata(dev);
+    struct amdgpu_device *adev = drm_to_adev(ddev);
+    struct amdgpu_uma_carveout_info *uma_info = &adev->uma_info;
+    uint32_t memory_carved;
+    ssize_t size = 0;
+
+    if (!uma_info || !uma_info->num_entries)
+        return -ENODEV;
+
+    for (int i = 0; i < uma_info->num_entries; i++) {
+        memory_carved = uma_info->entries[i].memory_carved_mb;
+        if (memory_carved >= SZ_1G/SZ_1M) {
+            size += sysfs_emit_at(buf, size, "%d: %s (%u GB)\n",
+                          i,
+                          uma_info->entries[i].name,
+                          memory_carved >> 10);
+        } else {
+            size += sysfs_emit_at(buf, size, "%d: %s (%u MB)\n",
+                          i,
+                          uma_info->entries[i].name,
+                          memory_carved);
+        }
+    }
+
+    return size;
+}
+static DEVICE_ATTR_RO(carveout_options);
+
+static ssize_t carveout_show(struct device *dev,
+                 struct device_attribute *attr,
+                 char *buf)
+{
+    struct drm_device *ddev = dev_get_drvdata(dev);
+    struct amdgpu_device *adev = drm_to_adev(ddev);
+
+    return sysfs_emit(buf, "%u\n", adev->uma_info.uma_option_index);
+}
+
+static ssize_t carveout_store(struct device *dev,
+                  struct device_attribute *attr,
+                  const char *buf, size_t count)
+{
+    struct drm_device *ddev = dev_get_drvdata(dev);
+    struct amdgpu_device *adev = drm_to_adev(ddev);
+    struct amdgpu_uma_carveout_info *uma_info = &adev->uma_info;
+    struct amdgpu_uma_carveout_option *opt;
+    unsigned long val;
+    uint8_t flags;
+    int r;
+
+    r = kstrtoul(buf, 10, &val);
+    if (r)
+        return r;
+
+    if (val >= uma_info->num_entries)
+        return -EINVAL;
+
+    val = array_index_nospec(val, uma_info->num_entries);
+    opt = &uma_info->entries[val];
+
+    if (!(opt->flags & AMDGPU_UMA_FLAG_AUTO) &&
+        !(opt->flags & AMDGPU_UMA_FLAG_CUSTOM)) {
+        drm_err_once(ddev, "Option %lu not supported due to lack of Custom/Auto flag", val);
+        return -EINVAL;
+    }
+
+    flags = opt->flags;
+    flags &= ~((flags & AMDGPU_UMA_FLAG_AUTO) >> 1);
+
+    guard(mutex)(&uma_info->update_lock);
+
+    r = amdgpu_acpi_set_uma_allocation_size(adev, val, flags);
+    if (r)
+        return r;
+
+    uma_info->uma_option_index = val;
+
+    return count;
+}
+static DEVICE_ATTR_RW(carveout);
+
+static struct attribute *amdgpu_uma_attrs[] = {
+    &dev_attr_carveout.attr,
+    &dev_attr_carveout_options.attr,
+    NULL
+};
+
+const struct attribute_group amdgpu_uma_attr_group = {
+    .name = "uma",
+    .attrs = amdgpu_uma_attrs
+};
+
+int amdgpu_acpi_uma_option_init(struct amdgpu_device *adev)
+{

To clarify on the comment about moving this to amdgpu_device -

UMA option is a device specific option which could be set through acpi. Options are retrieved through atom tables.

So the function names remain amdgpu_device_uma_option_init/fini() and init/fini are called within amdgpu_device.c


Couple of additional comments below -

Thanks,
Lijo

+    int rc;
+

It's better to have an early exit from here itself if it's not APU. Otherwise, the dbg prints will show up even on dGPUs.

There also needs to be a check for availability of BIOS (adev->bios) and (adev->is_atom_fw). For example in Instinct APUs, driver doesn't read bios image (adev->bios is NULL).

Thanks,
Lijo

+    if (!amdgpu_acpi_is_set_uma_allocation_size_supported())
+        return -ENODEV;
+
+    rc = amdgpu_atomfirmware_get_uma_carveout_info(adev, &adev- >uma_info);
+    if (rc) {
+        drm_dbg(adev_to_drm(adev),
+            "Failed to parse UMA carveout info from VBIOS: %d\n", rc);
+        goto out_info;
+    }
+
+    mutex_init(&adev->uma_info.update_lock);
+
+    rc = devm_device_add_group(adev->dev, &amdgpu_uma_attr_group);
+    if (rc) {
+        drm_dbg(adev_to_drm(adev), "Failed to add UMA carveout sysfs interfaces %d\n", rc);
+        goto out_attr;
+    }
+
+    return 0;
+
+out_attr:
+    mutex_destroy(&adev->uma_info.update_lock);
+out_info:
+    return rc;
+}
+
+void amdgpu_acpi_uma_option_fini(struct amdgpu_device *adev)
+{
+    struct amdgpu_uma_carveout_info *uma_info = &adev->uma_info;
+
+    if (!amdgpu_acpi_is_set_uma_allocation_size_supported())
+        return;
+
+    mutex_destroy(&uma_info->update_lock);
+    uma_info->num_entries = 0;
+}



Reply via email to