[PATCH v3 1/5] platform/x86/amd/hsmp: Serialize ACPI HSMP is_probed with a probe mutex

[PATCH v3 1/5] platform/x86/amd/hsmp: Serialize ACPI HSMP is_probed with a probe mutex

[Muralidhara M K]

Add hsmp_acpi_probe_mutex and hold it across ACPI probe, remove, and
init_acpi() so concurrent platform probes cannot race the global is_probed
handshake or the one-time socket allocation.  Use lockdep_assert_held() in
init_acpi() to catch incorrect locking under lockdep.

Signed-off-by: Muralidhara M K <muralidhara.mk@amd.com>
---
 drivers/platform/x86/amd/hsmp/acpi.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
index 72f68cef1297..206eb7897b61 100644
--- a/drivers/platform/x86/amd/hsmp/acpi.c
+++ b/drivers/platform/x86/amd/hsmp/acpi.c
@@ -18,8 +18,11 @@
 #include <linux/device.h>
 #include <linux/dev_printk.h>
 #include <linux/ioport.h>
+#include <linux/cleanup.h>
+#include <linux/lockdep.h>
 #include <linux/kstrtox.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/string.h>
 #include <linux/sysfs.h>
@@ -39,6 +42,8 @@
 
 static struct hsmp_plat_device *hsmp_pdev;
 
+static DEFINE_MUTEX(hsmp_acpi_probe_mutex);
+
 struct hsmp_sys_attr {
 	struct device_attribute dattr;
 	u32 msg_id;
@@ -482,11 +487,17 @@ static ssize_t hsmp_freq_limit_source_show(struct device *dev, struct device_att
 	return len;
 }
 
+/**
+ * init_acpi() - Parse ACPI mailbox resources for one socket and validate HSMP.
+ * @dev: ACPI companion device for this socket.
+ */
 static int init_acpi(struct device *dev)
 {
 	u16 sock_ind;
 	int ret;
 
+	lockdep_assert_held(&hsmp_acpi_probe_mutex);
+
 	ret = hsmp_get_uid(dev, &sock_ind);
 	if (ret)
 		return ret;
@@ -607,6 +618,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
 	if (!hsmp_pdev)
 		return -ENOMEM;
 
+	guard(mutex)(&hsmp_acpi_probe_mutex);
+
 	if (!hsmp_pdev->is_probed) {
 		hsmp_pdev->num_sockets = topology_max_packages();
 		if (!hsmp_pdev->num_sockets) {
@@ -642,6 +655,7 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
 
 static void hsmp_acpi_remove(struct platform_device *pdev)
 {
+	mutex_lock(&hsmp_acpi_probe_mutex);
 	/*
 	 * We register only one misc_device even on multi-socket system.
 	 * So, deregister should happen only once.
@@ -650,6 +664,7 @@ static void hsmp_acpi_remove(struct platform_device *pdev)
 		hsmp_misc_deregister();
 		hsmp_pdev->is_probed = false;
 	}
+	mutex_unlock(&hsmp_acpi_probe_mutex);
 }
 
 static struct platform_driver amd_hsmp_driver = {
-- 
2.34.1

Re: [PATCH v3 1/5] platform/x86/amd/hsmp: Serialize ACPI HSMP is_probed with a probe mutex

[Ilpo Järvinen]

On Tue, 7 Jul 2026, Muralidhara M K wrote:

> Add hsmp_acpi_probe_mutex and hold it across ACPI probe, remove, and
> init_acpi() so concurrent platform probes cannot race the global is_probed
> handshake or the one-time socket allocation.  Use lockdep_assert_held() in
> init_acpi() to catch incorrect locking under lockdep.
> 
> Signed-off-by: Muralidhara M K <muralidhara.mk@amd.com>
> ---
>  drivers/platform/x86/amd/hsmp/acpi.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
> index 72f68cef1297..206eb7897b61 100644
> --- a/drivers/platform/x86/amd/hsmp/acpi.c
> +++ b/drivers/platform/x86/amd/hsmp/acpi.c
> @@ -18,8 +18,11 @@
>  #include <linux/device.h>
>  #include <linux/dev_printk.h>
>  #include <linux/ioport.h>
> +#include <linux/cleanup.h>
> +#include <linux/lockdep.h>
>  #include <linux/kstrtox.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
>  #include <linux/platform_device.h>
>  #include <linux/string.h>
>  #include <linux/sysfs.h>
> @@ -39,6 +42,8 @@
>  
>  static struct hsmp_plat_device *hsmp_pdev;
>  
> +static DEFINE_MUTEX(hsmp_acpi_probe_mutex);
> +
>  struct hsmp_sys_attr {
>  	struct device_attribute dattr;
>  	u32 msg_id;
> @@ -482,11 +487,17 @@ static ssize_t hsmp_freq_limit_source_show(struct device *dev, struct device_att
>  	return len;
>  }
>  
> +/**
> + * init_acpi() - Parse ACPI mailbox resources for one socket and validate HSMP.
> + * @dev: ACPI companion device for this socket.
> + */
>  static int init_acpi(struct device *dev)
>  {
>  	u16 sock_ind;
>  	int ret;
>  
> +	lockdep_assert_held(&hsmp_acpi_probe_mutex);
> +
>  	ret = hsmp_get_uid(dev, &sock_ind);
>  	if (ret)
>  		return ret;
> @@ -607,6 +618,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
>  	if (!hsmp_pdev)
>  		return -ENOMEM;
>  
> +	guard(mutex)(&hsmp_acpi_probe_mutex);
> +
>  	if (!hsmp_pdev->is_probed) {
>  		hsmp_pdev->num_sockets = topology_max_packages();
>  		if (!hsmp_pdev->num_sockets) {
> @@ -642,6 +655,7 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
>  
>  static void hsmp_acpi_remove(struct platform_device *pdev)
>  {
> +	mutex_lock(&hsmp_acpi_probe_mutex);

Any particular reason why this too doesn't use guard()?

>  	/*
>  	 * We register only one misc_device even on multi-socket system.
>  	 * So, deregister should happen only once.
> @@ -650,6 +664,7 @@ static void hsmp_acpi_remove(struct platform_device *pdev)
>  		hsmp_misc_deregister();
>  		hsmp_pdev->is_probed = false;
>  	}
> +	mutex_unlock(&hsmp_acpi_probe_mutex);
>  }
>  
>  static struct platform_driver amd_hsmp_driver = {
> 

-- 
 i.

[PATCH v3 0/5] platform/x86/amd/hsmp: ACPI/platform HSMP concurrency and lifecycle hardening

[Muralidhara M K]

This series hardens the AMD HSMP ACPI and platform drivers against
probe/remove concurrency, use-after-free of the per-socket state, and
resource leaks across unbind/rebind cycles.

On multi-socket systems several ACPI platform devices are probed and
removed independently while a single /dev/hsmp (and the hwmon sysfs
attributes) drive a lock-free data plane.  The existing code raced the
global is_probed handshake and the one-time socket allocation, freed the
socket array from under in-flight hsmp_send_message() callers, and leaked
metric-table mappings on rebind.

The patches, in order:

  1. Serialize ACPI probe/remove/init_acpi() with a dedicated mutex so
     the is_probed handshake and the one-time socket allocation cannot
     race across per-socket platform devices.
  2. Map the metric-table DRAM explicitly and add per-socket mutexes.
  3. Add hsmp_sock_rwsem so the lock-free data plane is drained and kept
     out while a socket is torn down; wire the non-ACPI platform path
     into it.
  4. Refcount the ACPI socket platform devices with struct kref and run a
     coordinated release on the final put (deregister /dev/hsmp, unmap
     metric DRAM, free the socket array); clear the per-socket dev under
     the teardown write lock on both remove and probe failure.
  5. Drop any stale metric-table mapping before remapping on rebind.

Testing:
  - Each patch builds individually (W=1) with no new warnings; the series
    is bisectable.
  - checkpatch.pl --strict is clean on every patch.

Changes since v2:
  - This revision covers only the five ACPI/platform probe, teardown, and
    lifecycle patches.  The ACPI UID / _DSD mailbox validation and the
    sock->dev readiness-gate changes from v2 are accepted in maintainer branch.
  - Reworded the teardown rwsem comments in "Serialize the data plane
    against socket teardown" so they describe the drain contract in terms
    of a generic teardown path (a teardown path takes the write side)
    rather than attributing it to the ACPI path, which is wired into the
    drain in the following patch.

v2: https://patch.msgid.link/20260625123337.886435-1-muralidhara.mk@amd.com

Muralidhara M K (5):
  platform/x86/amd/hsmp: Serialize ACPI HSMP is_probed with a probe
    mutex
  platform/x86/amd/hsmp: Add explicit metric DRAM mapping and per-socket
    mutexes
  platform/x86/amd/hsmp: Serialize the data plane against socket
    teardown
  platform/x86/amd/hsmp: ACPI HSMP refcounted sockets and coordinated
    release
  platform/x86/amd/hsmp: Drop stale metric table mapping on rebind

 drivers/platform/x86/amd/hsmp/acpi.c | 147 ++++++++++++++++++++++++---
 drivers/platform/x86/amd/hsmp/hsmp.c | 112 ++++++++++++++++++--
 drivers/platform/x86/amd/hsmp/hsmp.h |  11 +-
 drivers/platform/x86/amd/hsmp/plat.c |  39 ++++++-
 4 files changed, 285 insertions(+), 24 deletions(-)


base-commit: ff7836fa850c2f815bc219f1e48f6ec8699f4ae7
-- 
2.34.1

[PATCH v3 1/5] platform/x86/amd/hsmp: Serialize ACPI HSMP is_probed with a probe mutex

[Muralidhara M K]

Add hsmp_acpi_probe_mutex and hold it across ACPI probe, remove, and
init_acpi() so concurrent platform probes cannot race the global is_probed
handshake or the one-time socket allocation.  Use lockdep_assert_held() in
init_acpi() to catch incorrect locking under lockdep.

Signed-off-by: Muralidhara M K <muralidhara.mk@amd.com>
---
 drivers/platform/x86/amd/hsmp/acpi.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
index 72f68cef1297..206eb7897b61 100644
--- a/drivers/platform/x86/amd/hsmp/acpi.c
+++ b/drivers/platform/x86/amd/hsmp/acpi.c
@@ -18,8 +18,11 @@
 #include <linux/device.h>
 #include <linux/dev_printk.h>
 #include <linux/ioport.h>
+#include <linux/cleanup.h>
+#include <linux/lockdep.h>
 #include <linux/kstrtox.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/platform_device.h>
 #include <linux/string.h>
 #include <linux/sysfs.h>
@@ -39,6 +42,8 @@
 
 static struct hsmp_plat_device *hsmp_pdev;
 
+static DEFINE_MUTEX(hsmp_acpi_probe_mutex);
+
 struct hsmp_sys_attr {
 	struct device_attribute dattr;
 	u32 msg_id;
@@ -482,11 +487,17 @@ static ssize_t hsmp_freq_limit_source_show(struct device *dev, struct device_att
 	return len;
 }
 
+/**
+ * init_acpi() - Parse ACPI mailbox resources for one socket and validate HSMP.
+ * @dev: ACPI companion device for this socket.
+ */
 static int init_acpi(struct device *dev)
 {
 	u16 sock_ind;
 	int ret;
 
+	lockdep_assert_held(&hsmp_acpi_probe_mutex);
+
 	ret = hsmp_get_uid(dev, &sock_ind);
 	if (ret)
 		return ret;
@@ -607,6 +618,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
 	if (!hsmp_pdev)
 		return -ENOMEM;
 
+	guard(mutex)(&hsmp_acpi_probe_mutex);
+
 	if (!hsmp_pdev->is_probed) {
 		hsmp_pdev->num_sockets = topology_max_packages();
 		if (!hsmp_pdev->num_sockets) {
@@ -642,6 +655,7 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
 
 static void hsmp_acpi_remove(struct platform_device *pdev)
 {
+	mutex_lock(&hsmp_acpi_probe_mutex);
 	/*
 	 * We register only one misc_device even on multi-socket system.
 	 * So, deregister should happen only once.
@@ -650,6 +664,7 @@ static void hsmp_acpi_remove(struct platform_device *pdev)
 		hsmp_misc_deregister();
 		hsmp_pdev->is_probed = false;
 	}
+	mutex_unlock(&hsmp_acpi_probe_mutex);
 }
 
 static struct platform_driver amd_hsmp_driver = {

base-commit: ff7836fa850c2f815bc219f1e48f6ec8699f4ae7
-- 
2.34.1