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, 93 insertions, 0 deletions

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
new file mode 100644
index 000000000..00e256204
--- /dev/null
+++ b/drivers/cpuidle/Kconfig
@@ -0,0 +1,93 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menu "CPU Idle"
+
+config CPU_IDLE
+	bool "CPU idle PM support"
+	default y if ACPI || PPC_PSERIES
+	select CPU_IDLE_GOV_LADDER if (!NO_HZ && !NO_HZ_IDLE)
+	select CPU_IDLE_GOV_MENU if (NO_HZ || NO_HZ_IDLE) && !CPU_IDLE_GOV_TEO
+	help
+	  CPU idle is a generic framework for supporting software-controlled
+	  idle processor power management.  It includes modular cross-platform
+	  governors that can be swapped during runtime.
+
+	  If you're using an ACPI-enabled platform, you should say Y here.
+
+if CPU_IDLE
+
+config CPU_IDLE_MULTIPLE_DRIVERS
+	bool
+
+config CPU_IDLE_GOV_LADDER
+	bool "Ladder governor (for periodic timer tick)"
+
+config CPU_IDLE_GOV_MENU
+	bool "Menu governor (for tickless system)"
+
+config CPU_IDLE_GOV_TEO
+	bool "Timer events oriented (TEO) governor (for tickless systems)"
+	help
+	  This governor implements a simplified idle state selection method
+	  focused on timer events and does not do any interactivity boosting.
+
+	  Some workloads benefit from using it and it generally should be safe
+	  to use.  Say Y here if you are not happy with the alternatives.
+
+config CPU_IDLE_GOV_HALTPOLL
+	bool "Haltpoll governor (for virtualized systems)"
+	depends on KVM_GUEST
+	help
+	  This governor implements haltpoll idle state selection, to be
+	  used in conjunction with the haltpoll cpuidle driver, allowing
+	  for polling for a certain amount of time before entering idle
+	  state.
+
+	  Some virtualized workloads benefit from using it.
+
+config DT_IDLE_STATES
+	bool
+
+config DT_IDLE_GENPD
+	depends on PM_GENERIC_DOMAINS_OF
+	bool
+
+menu "ARM CPU Idle Drivers"
+depends on ARM || ARM64
+source "drivers/cpuidle/Kconfig.arm"
+endmenu
+
+menu "MIPS CPU Idle Drivers"
+depends on MIPS
+source "drivers/cpuidle/Kconfig.mips"
+endmenu
+
+menu "POWERPC CPU Idle Drivers"
+depends on PPC
+source "drivers/cpuidle/Kconfig.powerpc"
+endmenu
+
+menu "RISC-V CPU Idle Drivers"
+depends on RISCV
+source "drivers/cpuidle/Kconfig.riscv"
+endmenu
+
+menu "S390 CPU Idle Drivers"
+depends on S390
+source "drivers/cpuidle/Kconfig.s390"
+endmenu
+
+config HALTPOLL_CPUIDLE
+	tristate "Halt poll cpuidle driver"
+	depends on X86 && KVM_GUEST
+	select CPU_IDLE_GOV_HALTPOLL
+	default y
+	help
+	 This option enables halt poll cpuidle driver, which allows to poll
+	 before halting in the guest (more efficient than polling in the
+	 host via halt_poll_ns for some scenarios).
+
+endif # CPU_IDLE
+
+config ARCH_NEEDS_CPU_IDLE_COUPLED
+	def_bool n
+endmenu