KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 156 insertions, 0 deletions

diff --git a/Documentation/gpu/amdgpu/driver-misc.rst b/Documentation/gpu/amdgpu/driver-misc.rst
new file mode 100644
index 000000000..e1a964c3a
--- /dev/null
+++ b/Documentation/gpu/amdgpu/driver-misc.rst
@@ -0,0 +1,156 @@
+================================
+ Misc AMDGPU driver information
+================================
+
+GPU Product Information
+=======================
+
+Information about the GPU can be obtained on certain cards
+via sysfs
+
+product_name
+------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: product_name
+
+product_number
+--------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: product_number
+
+serial_number
+-------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: serial_number
+
+fru_id
+-------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: fru_id
+
+manufacturer
+-------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_fru_eeprom.c
+   :doc: manufacturer
+
+unique_id
+---------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: unique_id
+
+board_info
+----------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: board_info
+
+GPU Memory Usage Information
+============================
+
+Various memory accounting can be accessed via sysfs
+
+mem_info_vram_total
+-------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vram_total
+
+mem_info_vram_used
+------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vram_used
+
+mem_info_vis_vram_total
+-----------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vis_vram_total
+
+mem_info_vis_vram_used
+----------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vis_vram_used
+
+mem_info_gtt_total
+------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+   :doc: mem_info_gtt_total
+
+mem_info_gtt_used
+-----------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+   :doc: mem_info_gtt_used
+
+PCIe Accounting Information
+===========================
+
+pcie_bw
+-------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: pcie_bw
+
+pcie_replay_count
+-----------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: pcie_replay_count
+
+GPU SmartShift Information
+==========================
+
+GPU SmartShift information via sysfs
+
+smartshift_apu_power
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: smartshift_apu_power
+
+smartshift_dgpu_power
+---------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: smartshift_dgpu_power
+
+smartshift_bias
+---------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/pm/amdgpu_pm.c
+   :doc: smartshift_bias
+
+UMA Carveout
+============
+
+Some versions of Atom ROM expose available options for the VRAM carveout sizes,
+and allow changes to the carveout size via the ATCS function code 0xA on supported
+BIOS implementations.
+
+For those platforms, users can use the following files under uma/ to set the
+carveout size, in a way similar to what Windows users can do in the "Tuning"
+tab in AMD Adrenalin.
+
+Note that for BIOS implementations that don't support this, these files will not
+be created at all.
+
+uma/carveout_options
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: uma/carveout_options
+
+uma/carveout
+--------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+   :doc: uma/carveout