drm/amdgpu: add UMA allocation interfaces to sysfs

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) <superm1@kernel.org>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Yo-Jung Leo Lin (AMD) <Leo.Lin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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>
@@ -381,6 +382,146 @@ static const struct attribute_group amdgpu_board_attrs_group = {
 	.is_visible = amdgpu_board_attrs_is_visible
 };
 
+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
+};
+
+static void amdgpu_uma_sysfs_init(struct amdgpu_device *adev)
+{
+	int rc;
+
+	if (!(adev->flags & AMD_IS_APU))
+		return;
+
+	if (!amdgpu_acpi_is_set_uma_allocation_size_supported())
+		return;
+
+	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;
+
+out_attr:
+	mutex_destroy(&adev->uma_info.update_lock);
+out_info:
+	return;
+}
+
+static void amdgpu_uma_sysfs_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;
+}
+
 static void amdgpu_device_get_pcie_info(struct amdgpu_device *adev);
 
 /**
@@ -4168,6 +4309,7 @@ static int amdgpu_device_sys_interface_init(struct amdgpu_device *adev)
 	amdgpu_fru_sysfs_init(adev);
 	amdgpu_reg_state_sysfs_init(adev);
 	amdgpu_xcp_sysfs_init(adev);
+	amdgpu_uma_sysfs_init(adev);
 
 	return r;
 }
@@ -4183,6 +4325,7 @@ static void amdgpu_device_sys_interface_fini(struct amdgpu_device *adev)
 
 	amdgpu_reg_state_sysfs_fini(adev);
 	amdgpu_xcp_sysfs_fini(adev);
+	amdgpu_uma_sysfs_fini(adev);
 }
 
 /**