x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

1 files changed, 116 insertions, 0 deletions

diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
new file mode 100644
index 000000000..bc0f38574
--- /dev/null
+++ b/drivers/vhost/Kconfig
@@ -0,0 +1,116 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config VHOST_IOTLB
+	tristate
+	help
+	  Generic IOTLB implementation for vhost and vringh.
+	  This option is selected by any driver which needs to support
+	  an IOMMU in software.
+
+config VHOST_RING
+	tristate
+	select VHOST_IOTLB
+	help
+	  This option is selected by any driver which needs to access
+	  the host side of a virtio ring.
+
+config VHOST_TASK
+	bool
+	default n
+
+config VHOST
+	tristate
+	select VHOST_IOTLB
+	select VHOST_TASK
+	help
+	  This option is selected by any driver which needs to access
+	  the core of vhost.
+
+menuconfig VHOST_MENU
+	bool "VHOST drivers"
+	default y
+
+if VHOST_MENU
+
+config VHOST_NET
+	tristate "Host kernel accelerator for virtio net"
+	depends on NET && EVENTFD && (TUN || !TUN) && (TAP || !TAP)
+	select VHOST
+	help
+	  This kernel module can be loaded in host kernel to accelerate
+	  guest networking with virtio_net. Not to be confused with virtio_net
+	  module itself which needs to be loaded in guest kernel.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called vhost_net.
+
+config VHOST_SCSI
+	tristate "VHOST_SCSI TCM fabric driver"
+	depends on TARGET_CORE && EVENTFD
+	select VHOST
+	select SG_POOL
+	default n
+	help
+	Say M here to enable the vhost_scsi TCM fabric module
+	for use with virtio-scsi guests
+
+config VHOST_VSOCK
+	tristate "vhost virtio-vsock driver"
+	depends on VSOCKETS && EVENTFD
+	select VHOST
+	select VIRTIO_VSOCKETS_COMMON
+	default n
+	help
+	This kernel module can be loaded in the host kernel to provide AF_VSOCK
+	sockets for communicating with guests.  The guests must have the
+	virtio_transport.ko driver loaded to use the virtio-vsock device.
+
+	To compile this driver as a module, choose M here: the module will be called
+	vhost_vsock.
+
+config VHOST_VDPA
+	tristate "Vhost driver for vDPA-based backend"
+	depends on EVENTFD
+	select VHOST
+	select IRQ_BYPASS_MANAGER
+	depends on VDPA
+	help
+	  This kernel module can be loaded in host kernel to accelerate
+	  guest virtio devices with the vDPA-based backends.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called vhost_vdpa.
+
+config VHOST_CROSS_ENDIAN_LEGACY
+	bool "Cross-endian support for vhost"
+	default n
+	help
+	  This option allows vhost to support guests with a different byte
+	  ordering from host while using legacy virtio.
+
+	  Userspace programs can control the feature using the
+	  VHOST_SET_VRING_ENDIAN and VHOST_GET_VRING_ENDIAN ioctls.
+
+	  This is only useful on a few platforms (ppc64 and arm64). Since it
+	  adds some overhead, it is disabled by default.
+
+	  If unsure, say "N".
+
+config VHOST_ENABLE_FORK_OWNER_CONTROL
+	bool "Enable VHOST_ENABLE_FORK_OWNER_CONTROL"
+	default y
+	help
+	  This option enables two IOCTLs: VHOST_SET_FORK_FROM_OWNER and
+	  VHOST_GET_FORK_FROM_OWNER. These allow userspace applications
+	  to modify the vhost worker mode for vhost devices.
+
+	  Also expose module parameter 'fork_from_owner_default' to allow users
+	  to configure the default mode for vhost workers.
+
+	  By default, `VHOST_ENABLE_FORK_OWNER_CONTROL` is set to `y`,
+	  users can change the worker thread mode as needed.
+	  If this config is disabled (n),the related IOCTLs and parameters will
+	  be unavailable.
+
+	  If unsure, say "Y".
+
+endif