[PATCH v4 0/3] AMD NB and SMN rework

[PATCH v4 0/3] AMD NB and SMN rework

[Yazen Ghannam]

Hi all,

This revision includes the remaining patches not yet accepted.

The only major change is to fix a build issue for an exported function.

Thanks,
Yazen

---
Changes in v4:
- Includes patches left out of v3. 
- Fix build issue for amd_smn_hsmp_rdwr(). Used Suma's suggestion.
- Link to v3: https://lore.kernel.org/r/20250107222847.3300430-1-yazen.ghannam@amd.com

Changes in v3:
- Based on public branch from Boris. 
- Add check for not finding any 'misc' devices during init. 
- Link to v2: https://lore.kernel.org/r/20241206161210.163701-1-yazen.ghannam@amd.com

Changes in v2:
- Rebase HSMP changes on latest upstream rework.
- Keep Node and SMN code together.
- Link to v1: https://lore.kernel.org/r/20241023172150.659002-1-yazen.ghannam@amd.com

---
Mario Limonciello (2):
      x86/amd_node: Add SMN offsets to exclusive region access
      x86/amd_node: Add support for debugfs access to SMN registers

Yazen Ghannam (1):
      x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD_NODE

 arch/x86/include/asm/amd_nb.h         |   1 -
 arch/x86/include/asm/amd_node.h       |  13 +++
 arch/x86/kernel/amd_nb.c              |   1 -
 arch/x86/kernel/amd_node.c            | 149 ++++++++++++++++++++++++++++++++++
 drivers/platform/x86/amd/hsmp/Kconfig |   2 +-
 drivers/platform/x86/amd/hsmp/acpi.c  |   7 +-
 drivers/platform/x86/amd/hsmp/hsmp.c  |   1 -
 drivers/platform/x86/amd/hsmp/hsmp.h  |   3 -
 drivers/platform/x86/amd/hsmp/plat.c  |  36 +++-----
 9 files changed, 179 insertions(+), 34 deletions(-)
---
base-commit: 25cb07b28aa8f42f3123a7b0bd09ea1d9a24fa28
change-id: 20241206-wip-x86-amd-nb-cleanup-6383ebdf8d25

[PATCH v4 1/3] x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD_NODE

[Yazen Ghannam]

The HSMP interface is just an SMN interface with different offsets.

Define an HSMP wrapper in the SMN code and have the HSMP platform driver
use that rather than a local solution.

Also, remove the "root" member from AMD_NB, since there are no more
users of it.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---

Notes:
    Link:
    https://lore.kernel.org/20241213152206.385573-1-yazen.ghannam@amd.com
    
    v2.2->v4
    * Was left out of v3 set.
    * Fix build issue for amd_smn_hsmp_rdwr().
    
    v2.1-v2.2:
    * Include <linux/build_bug.h> for static_assert()
    
    v2->v2.1:
    * Include static_assert() and comment for sysfs attributes.
    
    v1->v2:
    * Rebase on recent HSMP rework.

 arch/x86/include/asm/amd_nb.h         |  1 -
 arch/x86/include/asm/amd_node.h       | 13 +++++++++++++
 arch/x86/kernel/amd_nb.c              |  1 -
 arch/x86/kernel/amd_node.c            |  9 +++++++++
 drivers/platform/x86/amd/hsmp/Kconfig |  2 +-
 drivers/platform/x86/amd/hsmp/acpi.c  |  7 ++++---
 drivers/platform/x86/amd/hsmp/hsmp.c  |  1 -
 drivers/platform/x86/amd/hsmp/hsmp.h  |  3 ---
 drivers/platform/x86/amd/hsmp/plat.c  | 36 ++++++++++++-----------------------
 9 files changed, 39 insertions(+), 34 deletions(-)

diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
index 4c4efb93045e..adfa0854cf2d 100644
--- a/arch/x86/include/asm/amd_nb.h
+++ b/arch/x86/include/asm/amd_nb.h
@@ -27,7 +27,6 @@ struct amd_l3_cache {
 };
 
 struct amd_northbridge {
-	struct pci_dev *root;
 	struct pci_dev *misc;
 	struct pci_dev *link;
 	struct amd_l3_cache l3_cache;
diff --git a/arch/x86/include/asm/amd_node.h b/arch/x86/include/asm/amd_node.h
index 113ad3e8ee40..002c3afbd30f 100644
--- a/arch/x86/include/asm/amd_node.h
+++ b/arch/x86/include/asm/amd_node.h
@@ -30,7 +30,20 @@ static inline u16 amd_num_nodes(void)
 	return topology_amd_nodes_per_pkg() * topology_max_packages();
 }
 
+#ifdef CONFIG_AMD_NODE
 int __must_check amd_smn_read(u16 node, u32 address, u32 *value);
 int __must_check amd_smn_write(u16 node, u32 address, u32 value);
 
+/* Should only be used by the HSMP driver. */
+int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write);
+#else
+static inline int __must_check amd_smn_read(u16 node, u32 address, u32 *value) { return -ENODEV; }
+static inline int __must_check amd_smn_write(u16 node, u32 address, u32 value) { return -ENODEV; }
+
+static inline int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_AMD_NODE */
+
 #endif /*_ASM_X86_AMD_NODE_H_*/
diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index 11fac09e3a8c..24d7a87edf9c 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -73,7 +73,6 @@ static int amd_cache_northbridges(void)
 	amd_northbridges.nb = nb;
 
 	for (i = 0; i < amd_northbridges.num; i++) {
-		node_to_amd_nb(i)->root = amd_node_get_root(i);
 		node_to_amd_nb(i)->misc = amd_node_get_func(i, 3);
 
 		/*
diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index d2ec7fd555c5..65045f223c10 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -97,6 +97,9 @@ static DEFINE_MUTEX(smn_mutex);
 #define SMN_INDEX_OFFSET	0x60
 #define SMN_DATA_OFFSET		0x64
 
+#define HSMP_INDEX_OFFSET	0xc4
+#define HSMP_DATA_OFFSET	0xc8
+
 /*
  * SMN accesses may fail in ways that are difficult to detect here in the called
  * functions amd_smn_read() and amd_smn_write(). Therefore, callers must do
@@ -179,6 +182,12 @@ int __must_check amd_smn_write(u16 node, u32 address, u32 value)
 }
 EXPORT_SYMBOL_GPL(amd_smn_write);
 
+int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
+{
+	return __amd_smn_rw(HSMP_INDEX_OFFSET, HSMP_DATA_OFFSET, node, address, value, write);
+}
+EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
+
 static int amd_cache_roots(void)
 {
 	u16 node, num_nodes = amd_num_nodes();
diff --git a/drivers/platform/x86/amd/hsmp/Kconfig b/drivers/platform/x86/amd/hsmp/Kconfig
index 7d10d4462a45..d6f7a62d55b5 100644
--- a/drivers/platform/x86/amd/hsmp/Kconfig
+++ b/drivers/platform/x86/amd/hsmp/Kconfig
@@ -7,7 +7,7 @@ config AMD_HSMP
 	tristate
 
 menu "AMD HSMP Driver"
-	depends on AMD_NB || COMPILE_TEST
+	depends on AMD_NODE || COMPILE_TEST
 
 config AMD_HSMP_ACPI
 	tristate "AMD HSMP ACPI device driver"
diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
index 444b43be35a2..c1eccb3c80c5 100644
--- a/drivers/platform/x86/amd/hsmp/acpi.c
+++ b/drivers/platform/x86/amd/hsmp/acpi.c
@@ -10,7 +10,6 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
 #include <linux/acpi.h>
 #include <linux/device.h>
@@ -24,6 +23,8 @@
 
 #include <uapi/asm-generic/errno-base.h>
 
+#include <asm/amd_node.h>
+
 #include "hsmp.h"
 
 #define DRIVER_NAME		"amd_hsmp"
@@ -321,8 +322,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	if (!hsmp_pdev->is_probed) {
-		hsmp_pdev->num_sockets = amd_nb_num();
-		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
+		hsmp_pdev->num_sockets = amd_num_nodes();
+		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
 			return -ENODEV;
 
 		hsmp_pdev->sock = devm_kcalloc(&pdev->dev, hsmp_pdev->num_sockets,
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c
index 03164e30b3a5..a3ac09a90de4 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.c
+++ b/drivers/platform/x86/amd/hsmp/hsmp.c
@@ -8,7 +8,6 @@
  */
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
 #include <linux/acpi.h>
 #include <linux/delay.h>
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
index e852f0a947e4..af8b21f821d6 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.h
+++ b/drivers/platform/x86/amd/hsmp/hsmp.h
@@ -21,8 +21,6 @@
 
 #define HSMP_ATTR_GRP_NAME_SIZE	10
 
-#define MAX_AMD_SOCKETS 8
-
 #define HSMP_CDEV_NAME		"hsmp_cdev"
 #define HSMP_DEVNODE_NAME	"hsmp"
 
@@ -41,7 +39,6 @@ struct hsmp_socket {
 	void __iomem *virt_base_addr;
 	struct semaphore hsmp_sem;
 	char name[HSMP_ATTR_GRP_NAME_SIZE];
-	struct pci_dev *root;
 	struct device *dev;
 	u16 sock_ind;
 	int (*amd_hsmp_rdwr)(struct hsmp_socket *sock, u32 off, u32 *val, bool rw);
diff --git a/drivers/platform/x86/amd/hsmp/plat.c b/drivers/platform/x86/amd/hsmp/plat.c
index 02ca85762b68..b9782a078dbd 100644
--- a/drivers/platform/x86/amd/hsmp/plat.c
+++ b/drivers/platform/x86/amd/hsmp/plat.c
@@ -10,14 +10,16 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
+#include <linux/build_bug.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/sysfs.h>
 
+#include <asm/amd_node.h>
+
 #include "hsmp.h"
 
 #define DRIVER_NAME		"amd_hsmp"
@@ -34,28 +36,12 @@
 #define SMN_HSMP_MSG_RESP	0x0010980
 #define SMN_HSMP_MSG_DATA	0x00109E0
 
-#define HSMP_INDEX_REG		0xc4
-#define HSMP_DATA_REG		0xc8
-
 static struct hsmp_plat_device *hsmp_pdev;
 
 static int amd_hsmp_pci_rdwr(struct hsmp_socket *sock, u32 offset,
 			     u32 *value, bool write)
 {
-	int ret;
-
-	if (!sock->root)
-		return -ENODEV;
-
-	ret = pci_write_config_dword(sock->root, HSMP_INDEX_REG,
-				     sock->mbinfo.base_addr + offset);
-	if (ret)
-		return ret;
-
-	ret = (write ? pci_write_config_dword(sock->root, HSMP_DATA_REG, *value)
-		     : pci_read_config_dword(sock->root, HSMP_DATA_REG, value));
-
-	return ret;
+	return amd_smn_hsmp_rdwr(sock->sock_ind, sock->mbinfo.base_addr + offset, value, write);
 }
 
 static ssize_t hsmp_metric_tbl_plat_read(struct file *filp, struct kobject *kobj,
@@ -95,7 +81,12 @@ static umode_t hsmp_is_sock_attr_visible(struct kobject *kobj,
  * Static array of 8 + 1(for NULL) elements is created below
  * to create sysfs groups for sockets.
  * is_bin_visible function is used to show / hide the necessary groups.
+ *
+ * Validate the maximum number against MAX_AMD_NUM_NODES. If this changes,
+ * then the attributes and groups below must be adjusted.
  */
+static_assert(MAX_AMD_NUM_NODES == 8);
+
 #define HSMP_BIN_ATTR(index, _list)					\
 static const struct bin_attribute attr##index = {			\
 	.attr = { .name = HSMP_METRICS_TABLE_NAME, .mode = 0444},	\
@@ -159,10 +150,7 @@ static int init_platform_device(struct device *dev)
 	int ret, i;
 
 	for (i = 0; i < hsmp_pdev->num_sockets; i++) {
-		if (!node_to_amd_nb(i))
-			return -ENODEV;
 		sock = &hsmp_pdev->sock[i];
-		sock->root			= node_to_amd_nb(i)->root;
 		sock->sock_ind			= i;
 		sock->dev			= dev;
 		sock->mbinfo.base_addr		= SMN_HSMP_BASE;
@@ -305,11 +293,11 @@ static int __init hsmp_plt_init(void)
 		return -ENOMEM;
 
 	/*
-	 * amd_nb_num() returns number of SMN/DF interfaces present in the system
+	 * amd_num_nodes() returns number of SMN/DF interfaces present in the system
 	 * if we have N SMN/DF interfaces that ideally means N sockets
 	 */
-	hsmp_pdev->num_sockets = amd_nb_num();
-	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
+	hsmp_pdev->num_sockets = amd_num_nodes();
+	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
 		return ret;
 
 	ret = platform_driver_register(&amd_hsmp_driver);

-- 
2.43.0

[PATCH v4 2/3] x86/amd_node: Add SMN offsets to exclusive region access

[Yazen Ghannam]

From: Mario Limonciello <mario.limonciello@amd.com>

Offsets 0x60 and 0x64 are used internally by kernel drivers that call
the amd_smn_read() and amd_smn_write() functions. If userspace accesses
the regions at the same time as the kernel it may cause malfunctions in
drivers using the offsets.

Add these offsets to the exclusions so that the kernel is tainted if a
non locked down userspace tries to access them.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---

Notes:
    Link:
    https://lore.kernel.org/20241206161210.163701-16-yazen.ghannam@amd.com
    
    v2->v4:
    * Was left out of v3.
    * No change.
    
    v1->v2:
    * No change.

 arch/x86/kernel/amd_node.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index 65045f223c10..ac571948cb35 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -93,6 +93,7 @@ static struct pci_dev **amd_roots;
 
 /* Protect the PCI config register pairs used for SMN. */
 static DEFINE_MUTEX(smn_mutex);
+static bool smn_exclusive;
 
 #define SMN_INDEX_OFFSET	0x60
 #define SMN_DATA_OFFSET		0x64
@@ -149,6 +150,9 @@ static int __amd_smn_rw(u8 i_off, u8 d_off, u16 node, u32 address, u32 *value, b
 	if (!root)
 		return err;
 
+	if (!smn_exclusive)
+		return err;
+
 	guard(mutex)(&smn_mutex);
 
 	err = pci_write_config_dword(root, i_off, address);
@@ -202,6 +206,39 @@ static int amd_cache_roots(void)
 	return 0;
 }
 
+static int reserve_root_config_spaces(void)
+{
+	struct pci_dev *root = NULL;
+	struct pci_bus *bus = NULL;
+
+	while ((bus = pci_find_next_bus(bus))) {
+		/* Root device is Device 0 Function 0 on each Primary Bus. */
+		root = pci_get_slot(bus, 0);
+		if (!root)
+			continue;
+
+		if (root->vendor != PCI_VENDOR_ID_AMD &&
+		    root->vendor != PCI_VENDOR_ID_HYGON)
+			continue;
+
+		pci_dbg(root, "Reserving PCI config space\n");
+
+		/*
+		 * There are a few SMN index/data pairs and other registers
+		 * that shouldn't be accessed by user space.
+		 * So reserve the entire PCI config space for simplicity rather
+		 * than covering specific registers piecemeal.
+		 */
+		if (!pci_request_config_region_exclusive(root, 0, PCI_CFG_SPACE_SIZE, NULL)) {
+			pci_err(root, "Failed to reserve config space\n");
+			return -EEXIST;
+		}
+	}
+
+	smn_exclusive = true;
+	return 0;
+}
+
 static int __init amd_smn_init(void)
 {
 	int err;
@@ -218,6 +255,10 @@ static int __init amd_smn_init(void)
 	if (err)
 		return err;
 
+	err = reserve_root_config_spaces();
+	if (err)
+		return err;
+
 	return 0;
 }
 

-- 
2.43.0

[PATCH v4 3/3] x86/amd_node: Add support for debugfs access to SMN registers

[Yazen Ghannam]

From: Mario Limonciello <mario.limonciello@amd.com>

There are certain registers on AMD Zen systems that can only be
accessed through SMN.

Introduce a new interface that provides debugfs files for accessing SMN.
As this introduces the capability for userspace to manipulate the
hardware in unpredictable ways, taint the kernel when writing.

Include a kernel parameter to enable the debugfs interface. This is
intentionally left undocumented to discourage use of the interface.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---

Notes:
    Link:
    https://lore.kernel.org/20241206161210.163701-17-yazen.ghannam@amd.com
    
    v2->v4:
    * Was left out of v3.
    * No change.
    
    v1->v2:
    * Use TAINT_CPU_OUT_OF_SPEC.
    * Add parameter to enable debugfs interface.
    * Validate node input from user.

 arch/x86/kernel/amd_node.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index ac571948cb35..b670fa85c61b 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -8,6 +8,7 @@
  * Author: Yazen Ghannam <Yazen.Ghannam@amd.com>
  */
 
+#include <linux/debugfs.h>
 #include <asm/amd_node.h>
 
 /*
@@ -192,6 +193,87 @@ int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write
 }
 EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
 
+static struct dentry *debugfs_dir;
+static u16 debug_node;
+static u32 debug_address;
+
+static ssize_t smn_node_write(struct file *file, const char __user *userbuf,
+			      size_t count, loff_t *ppos)
+{
+	u16 node;
+	int ret;
+
+	ret = kstrtou16_from_user(userbuf, count, 0, &node);
+	if (ret)
+		return ret;
+
+	if (node >= amd_num_nodes())
+		return -ENODEV;
+
+	debug_node = node;
+	return count;
+}
+
+static int smn_node_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "0x%08x\n", debug_node);
+	return 0;
+}
+
+static ssize_t smn_address_write(struct file *file, const char __user *userbuf,
+				 size_t count, loff_t *ppos)
+{
+	int ret;
+
+	ret = kstrtouint_from_user(userbuf, count, 0, &debug_address);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static int smn_address_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "0x%08x\n", debug_address);
+	return 0;
+}
+
+static int smn_value_show(struct seq_file *m, void *v)
+{
+	u32 val;
+	int ret;
+
+	ret = amd_smn_read(debug_node, debug_address, &val);
+	if (ret)
+		return ret;
+
+	seq_printf(m, "0x%08x\n", val);
+	return 0;
+}
+
+static ssize_t smn_value_write(struct file *file, const char __user *userbuf,
+			       size_t count, loff_t *ppos)
+{
+	u32 val;
+	int ret;
+
+	ret = kstrtouint_from_user(userbuf, count, 0, &val);
+	if (ret)
+		return ret;
+
+	add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
+
+	ret = amd_smn_write(debug_node, debug_address, val);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_node);
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_address);
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_value);
+
 static int amd_cache_roots(void)
 {
 	u16 node, num_nodes = amd_num_nodes();
@@ -239,6 +321,15 @@ static int reserve_root_config_spaces(void)
 	return 0;
 }
 
+static bool enable_dfs;
+
+static int __init amd_smn_enable_dfs(char *str)
+{
+	enable_dfs = true;
+	return 1;
+}
+__setup("amd_smn_debugfs_enable", amd_smn_enable_dfs);
+
 static int __init amd_smn_init(void)
 {
 	int err;
@@ -259,6 +350,14 @@ static int __init amd_smn_init(void)
 	if (err)
 		return err;
 
+	if (enable_dfs) {
+		debugfs_dir = debugfs_create_dir("amd_smn", arch_debugfs_dir);
+
+		debugfs_create_file("node",	0600, debugfs_dir, NULL, &smn_node_fops);
+		debugfs_create_file("address",	0600, debugfs_dir, NULL, &smn_address_fops);
+		debugfs_create_file("value",	0600, debugfs_dir, NULL, &smn_value_fops);
+	}
+
 	return 0;
 }
 

-- 
2.43.0

Re: [PATCH v4 1/3] x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD_NODE

[Carlos Bilbao]

On 1/30/25 13:48, Yazen Ghannam wrote:

> The HSMP interface is just an SMN interface with different offsets.
>
> Define an HSMP wrapper in the SMN code and have the HSMP platform driver
> use that rather than a local solution.
>
> Also, remove the "root" member from AMD_NB, since there are no more
> users of it.
>
> Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
> ---
>
> Notes:
>     Link:
>     https://lore.kernel.org/20241213152206.385573-1-yazen.ghannam@amd.com
>     
>     v2.2->v4
>     * Was left out of v3 set.
>     * Fix build issue for amd_smn_hsmp_rdwr().
>     
>     v2.1-v2.2:
>     * Include <linux/build_bug.h> for static_assert()
>     
>     v2->v2.1:
>     * Include static_assert() and comment for sysfs attributes.
>     
>     v1->v2:
>     * Rebase on recent HSMP rework.
>
>  arch/x86/include/asm/amd_nb.h         |  1 -
>  arch/x86/include/asm/amd_node.h       | 13 +++++++++++++
>  arch/x86/kernel/amd_nb.c              |  1 -
>  arch/x86/kernel/amd_node.c            |  9 +++++++++
>  drivers/platform/x86/amd/hsmp/Kconfig |  2 +-
>  drivers/platform/x86/amd/hsmp/acpi.c  |  7 ++++---
>  drivers/platform/x86/amd/hsmp/hsmp.c  |  1 -
>  drivers/platform/x86/amd/hsmp/hsmp.h  |  3 ---
>  drivers/platform/x86/amd/hsmp/plat.c  | 36 ++++++++++++-----------------------
>  9 files changed, 39 insertions(+), 34 deletions(-)
>
> diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
> index 4c4efb93045e..adfa0854cf2d 100644
> --- a/arch/x86/include/asm/amd_nb.h
> +++ b/arch/x86/include/asm/amd_nb.h
> @@ -27,7 +27,6 @@ struct amd_l3_cache {
>  };
>  
>  struct amd_northbridge {
> -	struct pci_dev *root;
>  	struct pci_dev *misc;
>  	struct pci_dev *link;
>  	struct amd_l3_cache l3_cache;
> diff --git a/arch/x86/include/asm/amd_node.h b/arch/x86/include/asm/amd_node.h
> index 113ad3e8ee40..002c3afbd30f 100644
> --- a/arch/x86/include/asm/amd_node.h
> +++ b/arch/x86/include/asm/amd_node.h
> @@ -30,7 +30,20 @@ static inline u16 amd_num_nodes(void)
>  	return topology_amd_nodes_per_pkg() * topology_max_packages();
>  }
>  
> +#ifdef CONFIG_AMD_NODE
>  int __must_check amd_smn_read(u16 node, u32 address, u32 *value);
>  int __must_check amd_smn_write(u16 node, u32 address, u32 value);
>  
> +/* Should only be used by the HSMP driver. */
> +int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write);
> +#else
> +static inline int __must_check amd_smn_read(u16 node, u32 address, u32 *value) { return -ENODEV; }
> +static inline int __must_check amd_smn_write(u16 node, u32 address, u32 value) { return -ENODEV; }
> +
> +static inline int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
> +{
> +	return -ENODEV;
> +}
> +#endif /* CONFIG_AMD_NODE */
> +
>  #endif /*_ASM_X86_AMD_NODE_H_*/
> diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
> index 11fac09e3a8c..24d7a87edf9c 100644
> --- a/arch/x86/kernel/amd_nb.c
> +++ b/arch/x86/kernel/amd_nb.c
> @@ -73,7 +73,6 @@ static int amd_cache_northbridges(void)
>  	amd_northbridges.nb = nb;
>  
>  	for (i = 0; i < amd_northbridges.num; i++) {
> -		node_to_amd_nb(i)->root = amd_node_get_root(i);
>  		node_to_amd_nb(i)->misc = amd_node_get_func(i, 3);
>  
>  		/*
> diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
> index d2ec7fd555c5..65045f223c10 100644
> --- a/arch/x86/kernel/amd_node.c
> +++ b/arch/x86/kernel/amd_node.c
> @@ -97,6 +97,9 @@ static DEFINE_MUTEX(smn_mutex);
>  #define SMN_INDEX_OFFSET	0x60
>  #define SMN_DATA_OFFSET		0x64
>  
> +#define HSMP_INDEX_OFFSET	0xc4
> +#define HSMP_DATA_OFFSET	0xc8
> +
>  /*
>   * SMN accesses may fail in ways that are difficult to detect here in the called
>   * functions amd_smn_read() and amd_smn_write(). Therefore, callers must do
> @@ -179,6 +182,12 @@ int __must_check amd_smn_write(u16 node, u32 address, u32 value)
>  }
>  EXPORT_SYMBOL_GPL(amd_smn_write);
>  
> +int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
> +{
> +	return __amd_smn_rw(HSMP_INDEX_OFFSET, HSMP_DATA_OFFSET, node, address, value, write);
> +}
> +EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
> +
>  static int amd_cache_roots(void)
>  {
>  	u16 node, num_nodes = amd_num_nodes();
> diff --git a/drivers/platform/x86/amd/hsmp/Kconfig b/drivers/platform/x86/amd/hsmp/Kconfig
> index 7d10d4462a45..d6f7a62d55b5 100644
> --- a/drivers/platform/x86/amd/hsmp/Kconfig
> +++ b/drivers/platform/x86/amd/hsmp/Kconfig
> @@ -7,7 +7,7 @@ config AMD_HSMP
>  	tristate
>  
>  menu "AMD HSMP Driver"
> -	depends on AMD_NB || COMPILE_TEST
> +	depends on AMD_NODE || COMPILE_TEST
>  
>  config AMD_HSMP_ACPI
>  	tristate "AMD HSMP ACPI device driver"
> diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
> index 444b43be35a2..c1eccb3c80c5 100644
> --- a/drivers/platform/x86/amd/hsmp/acpi.c
> +++ b/drivers/platform/x86/amd/hsmp/acpi.c
> @@ -10,7 +10,6 @@
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
>  #include <asm/amd_hsmp.h>
> -#include <asm/amd_nb.h>
>  
>  #include <linux/acpi.h>
>  #include <linux/device.h>
> @@ -24,6 +23,8 @@
>  
>  #include <uapi/asm-generic/errno-base.h>
>  
> +#include <asm/amd_node.h>
> +
>  #include "hsmp.h"
>  
>  #define DRIVER_NAME		"amd_hsmp"
> @@ -321,8 +322,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	if (!hsmp_pdev->is_probed) {
> -		hsmp_pdev->num_sockets = amd_nb_num();
> -		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
> +		hsmp_pdev->num_sockets = amd_num_nodes();
> +		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
>  			return -ENODEV;
>  
>  		hsmp_pdev->sock = devm_kcalloc(&pdev->dev, hsmp_pdev->num_sockets,
> diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c
> index 03164e30b3a5..a3ac09a90de4 100644
> --- a/drivers/platform/x86/amd/hsmp/hsmp.c
> +++ b/drivers/platform/x86/amd/hsmp/hsmp.c
> @@ -8,7 +8,6 @@
>   */
>  
>  #include <asm/amd_hsmp.h>
> -#include <asm/amd_nb.h>
>  
>  #include <linux/acpi.h>
>  #include <linux/delay.h>
> diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
> index e852f0a947e4..af8b21f821d6 100644
> --- a/drivers/platform/x86/amd/hsmp/hsmp.h
> +++ b/drivers/platform/x86/amd/hsmp/hsmp.h
> @@ -21,8 +21,6 @@
>  
>  #define HSMP_ATTR_GRP_NAME_SIZE	10
>  
> -#define MAX_AMD_SOCKETS 8
> -
>  #define HSMP_CDEV_NAME		"hsmp_cdev"
>  #define HSMP_DEVNODE_NAME	"hsmp"
>  
> @@ -41,7 +39,6 @@ struct hsmp_socket {
>  	void __iomem *virt_base_addr;
>  	struct semaphore hsmp_sem;
>  	char name[HSMP_ATTR_GRP_NAME_SIZE];
> -	struct pci_dev *root;
>  	struct device *dev;
>  	u16 sock_ind;
>  	int (*amd_hsmp_rdwr)(struct hsmp_socket *sock, u32 off, u32 *val, bool rw);
> diff --git a/drivers/platform/x86/amd/hsmp/plat.c b/drivers/platform/x86/amd/hsmp/plat.c
> index 02ca85762b68..b9782a078dbd 100644
> --- a/drivers/platform/x86/amd/hsmp/plat.c
> +++ b/drivers/platform/x86/amd/hsmp/plat.c
> @@ -10,14 +10,16 @@
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
>  #include <asm/amd_hsmp.h>
> -#include <asm/amd_nb.h>
>  
> +#include <linux/build_bug.h>
>  #include <linux/device.h>
>  #include <linux/module.h>
>  #include <linux/pci.h>
>  #include <linux/platform_device.h>
>  #include <linux/sysfs.h>
>  
> +#include <asm/amd_node.h>
> +
>  #include "hsmp.h"
>  
>  #define DRIVER_NAME		"amd_hsmp"
> @@ -34,28 +36,12 @@
>  #define SMN_HSMP_MSG_RESP	0x0010980
>  #define SMN_HSMP_MSG_DATA	0x00109E0
>  
> -#define HSMP_INDEX_REG		0xc4
> -#define HSMP_DATA_REG		0xc8
> -
>  static struct hsmp_plat_device *hsmp_pdev;
>  
>  static int amd_hsmp_pci_rdwr(struct hsmp_socket *sock, u32 offset,
>  			     u32 *value, bool write)
>  {
> -	int ret;
> -
> -	if (!sock->root)
> -		return -ENODEV;
> -
> -	ret = pci_write_config_dword(sock->root, HSMP_INDEX_REG,
> -				     sock->mbinfo.base_addr + offset);
> -	if (ret)
> -		return ret;
> -
> -	ret = (write ? pci_write_config_dword(sock->root, HSMP_DATA_REG, *value)
> -		     : pci_read_config_dword(sock->root, HSMP_DATA_REG, value));
> -
> -	return ret;
> +	return amd_smn_hsmp_rdwr(sock->sock_ind, sock->mbinfo.base_addr + offset, value, write);
>  }
>  
>  static ssize_t hsmp_metric_tbl_plat_read(struct file *filp, struct kobject *kobj,
> @@ -95,7 +81,12 @@ static umode_t hsmp_is_sock_attr_visible(struct kobject *kobj,
>   * Static array of 8 + 1(for NULL) elements is created below
>   * to create sysfs groups for sockets.
>   * is_bin_visible function is used to show / hide the necessary groups.
> + *
> + * Validate the maximum number against MAX_AMD_NUM_NODES. If this changes,
> + * then the attributes and groups below must be adjusted.
>   */
> +static_assert(MAX_AMD_NUM_NODES == 8);
> +
>  #define HSMP_BIN_ATTR(index, _list)					\
>  static const struct bin_attribute attr##index = {			\
>  	.attr = { .name = HSMP_METRICS_TABLE_NAME, .mode = 0444},	\
> @@ -159,10 +150,7 @@ static int init_platform_device(struct device *dev)
>  	int ret, i;
>  
>  	for (i = 0; i < hsmp_pdev->num_sockets; i++) {
> -		if (!node_to_amd_nb(i))
> -			return -ENODEV;
>  		sock = &hsmp_pdev->sock[i];
> -		sock->root			= node_to_amd_nb(i)->root;
>  		sock->sock_ind			= i;
>  		sock->dev			= dev;
>  		sock->mbinfo.base_addr		= SMN_HSMP_BASE;
> @@ -305,11 +293,11 @@ static int __init hsmp_plt_init(void)
>  		return -ENOMEM;
>  
>  	/*
> -	 * amd_nb_num() returns number of SMN/DF interfaces present in the system
> +	 * amd_num_nodes() returns number of SMN/DF interfaces present in the system
>  	 * if we have N SMN/DF interfaces that ideally means N sockets
>  	 */
> -	hsmp_pdev->num_sockets = amd_nb_num();
> -	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
> +	hsmp_pdev->num_sockets = amd_num_nodes();
> +	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
>  		return ret;
>  
>  	ret = platform_driver_register(&amd_hsmp_driver);
>

Reviewed-by: Carlos Bilbao <carlos.bilbao@kernel.org>


Thanks, Carlos

Re: [PATCH v4 1/3] x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD_NODE

[Ilpo Järvinen]

[-- Attachment #1: Type: text/plain, Size: 10368 bytes --]

On Thu, 30 Jan 2025, Yazen Ghannam wrote:

> The HSMP interface is just an SMN interface with different offsets.
> 
> Define an HSMP wrapper in the SMN code and have the HSMP platform driver
> use that rather than a local solution.
> 
> Also, remove the "root" member from AMD_NB, since there are no more
> users of it.
> 
> Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
> ---
> 
> Notes:
>     Link:
>     https://lore.kernel.org/20241213152206.385573-1-yazen.ghannam@amd.com
>     
>     v2.2->v4
>     * Was left out of v3 set.
>     * Fix build issue for amd_smn_hsmp_rdwr().
>     
>     v2.1-v2.2:
>     * Include <linux/build_bug.h> for static_assert()
>     
>     v2->v2.1:
>     * Include static_assert() and comment for sysfs attributes.
>     
>     v1->v2:
>     * Rebase on recent HSMP rework.
> 
>  arch/x86/include/asm/amd_nb.h         |  1 -
>  arch/x86/include/asm/amd_node.h       | 13 +++++++++++++
>  arch/x86/kernel/amd_nb.c              |  1 -
>  arch/x86/kernel/amd_node.c            |  9 +++++++++
>  drivers/platform/x86/amd/hsmp/Kconfig |  2 +-
>  drivers/platform/x86/amd/hsmp/acpi.c  |  7 ++++---
>  drivers/platform/x86/amd/hsmp/hsmp.c  |  1 -
>  drivers/platform/x86/amd/hsmp/hsmp.h  |  3 ---
>  drivers/platform/x86/amd/hsmp/plat.c  | 36 ++++++++++++-----------------------
>  9 files changed, 39 insertions(+), 34 deletions(-)
> 
> diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
> index 4c4efb93045e..adfa0854cf2d 100644
> --- a/arch/x86/include/asm/amd_nb.h
> +++ b/arch/x86/include/asm/amd_nb.h
> @@ -27,7 +27,6 @@ struct amd_l3_cache {
>  };
>  
>  struct amd_northbridge {
> -	struct pci_dev *root;
>  	struct pci_dev *misc;
>  	struct pci_dev *link;
>  	struct amd_l3_cache l3_cache;
> diff --git a/arch/x86/include/asm/amd_node.h b/arch/x86/include/asm/amd_node.h
> index 113ad3e8ee40..002c3afbd30f 100644
> --- a/arch/x86/include/asm/amd_node.h
> +++ b/arch/x86/include/asm/amd_node.h
> @@ -30,7 +30,20 @@ static inline u16 amd_num_nodes(void)
>  	return topology_amd_nodes_per_pkg() * topology_max_packages();
>  }
>  
> +#ifdef CONFIG_AMD_NODE
>  int __must_check amd_smn_read(u16 node, u32 address, u32 *value);
>  int __must_check amd_smn_write(u16 node, u32 address, u32 value);
>  
> +/* Should only be used by the HSMP driver. */
> +int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write);
> +#else
> +static inline int __must_check amd_smn_read(u16 node, u32 address, u32 *value) { return -ENODEV; }
> +static inline int __must_check amd_smn_write(u16 node, u32 address, u32 value) { return -ENODEV; }
> +
> +static inline int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
> +{
> +	return -ENODEV;
> +}
> +#endif /* CONFIG_AMD_NODE */
> +
>  #endif /*_ASM_X86_AMD_NODE_H_*/
> diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
> index 11fac09e3a8c..24d7a87edf9c 100644
> --- a/arch/x86/kernel/amd_nb.c
> +++ b/arch/x86/kernel/amd_nb.c
> @@ -73,7 +73,6 @@ static int amd_cache_northbridges(void)
>  	amd_northbridges.nb = nb;
>  
>  	for (i = 0; i < amd_northbridges.num; i++) {
> -		node_to_amd_nb(i)->root = amd_node_get_root(i);
>  		node_to_amd_nb(i)->misc = amd_node_get_func(i, 3);
>  
>  		/*
> diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
> index d2ec7fd555c5..65045f223c10 100644
> --- a/arch/x86/kernel/amd_node.c
> +++ b/arch/x86/kernel/amd_node.c
> @@ -97,6 +97,9 @@ static DEFINE_MUTEX(smn_mutex);
>  #define SMN_INDEX_OFFSET	0x60
>  #define SMN_DATA_OFFSET		0x64
>  
> +#define HSMP_INDEX_OFFSET	0xc4
> +#define HSMP_DATA_OFFSET	0xc8
> +
>  /*
>   * SMN accesses may fail in ways that are difficult to detect here in the called
>   * functions amd_smn_read() and amd_smn_write(). Therefore, callers must do
> @@ -179,6 +182,12 @@ int __must_check amd_smn_write(u16 node, u32 address, u32 value)
>  }
>  EXPORT_SYMBOL_GPL(amd_smn_write);
>  
> +int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
> +{
> +	return __amd_smn_rw(HSMP_INDEX_OFFSET, HSMP_DATA_OFFSET, node, address, value, write);
> +}
> +EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
> +
>  static int amd_cache_roots(void)
>  {
>  	u16 node, num_nodes = amd_num_nodes();
> diff --git a/drivers/platform/x86/amd/hsmp/Kconfig b/drivers/platform/x86/amd/hsmp/Kconfig
> index 7d10d4462a45..d6f7a62d55b5 100644
> --- a/drivers/platform/x86/amd/hsmp/Kconfig
> +++ b/drivers/platform/x86/amd/hsmp/Kconfig
> @@ -7,7 +7,7 @@ config AMD_HSMP
>  	tristate
>  
>  menu "AMD HSMP Driver"
> -	depends on AMD_NB || COMPILE_TEST
> +	depends on AMD_NODE || COMPILE_TEST
>  
>  config AMD_HSMP_ACPI
>  	tristate "AMD HSMP ACPI device driver"
> diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
> index 444b43be35a2..c1eccb3c80c5 100644
> --- a/drivers/platform/x86/amd/hsmp/acpi.c
> +++ b/drivers/platform/x86/amd/hsmp/acpi.c
> @@ -10,7 +10,6 @@
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
>  #include <asm/amd_hsmp.h>
> -#include <asm/amd_nb.h>
>  
>  #include <linux/acpi.h>
>  #include <linux/device.h>
> @@ -24,6 +23,8 @@
>  
>  #include <uapi/asm-generic/errno-base.h>
>  
> +#include <asm/amd_node.h>
> +
>  #include "hsmp.h"
>  
>  #define DRIVER_NAME		"amd_hsmp"
> @@ -321,8 +322,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	if (!hsmp_pdev->is_probed) {
> -		hsmp_pdev->num_sockets = amd_nb_num();
> -		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
> +		hsmp_pdev->num_sockets = amd_num_nodes();
> +		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
>  			return -ENODEV;
>  
>  		hsmp_pdev->sock = devm_kcalloc(&pdev->dev, hsmp_pdev->num_sockets,
> diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c
> index 03164e30b3a5..a3ac09a90de4 100644
> --- a/drivers/platform/x86/amd/hsmp/hsmp.c
> +++ b/drivers/platform/x86/amd/hsmp/hsmp.c
> @@ -8,7 +8,6 @@
>   */
>  
>  #include <asm/amd_hsmp.h>
> -#include <asm/amd_nb.h>
>  
>  #include <linux/acpi.h>
>  #include <linux/delay.h>
> diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
> index e852f0a947e4..af8b21f821d6 100644
> --- a/drivers/platform/x86/amd/hsmp/hsmp.h
> +++ b/drivers/platform/x86/amd/hsmp/hsmp.h
> @@ -21,8 +21,6 @@
>  
>  #define HSMP_ATTR_GRP_NAME_SIZE	10
>  
> -#define MAX_AMD_SOCKETS 8
> -
>  #define HSMP_CDEV_NAME		"hsmp_cdev"
>  #define HSMP_DEVNODE_NAME	"hsmp"
>  
> @@ -41,7 +39,6 @@ struct hsmp_socket {
>  	void __iomem *virt_base_addr;
>  	struct semaphore hsmp_sem;
>  	char name[HSMP_ATTR_GRP_NAME_SIZE];
> -	struct pci_dev *root;
>  	struct device *dev;
>  	u16 sock_ind;
>  	int (*amd_hsmp_rdwr)(struct hsmp_socket *sock, u32 off, u32 *val, bool rw);
> diff --git a/drivers/platform/x86/amd/hsmp/plat.c b/drivers/platform/x86/amd/hsmp/plat.c
> index 02ca85762b68..b9782a078dbd 100644
> --- a/drivers/platform/x86/amd/hsmp/plat.c
> +++ b/drivers/platform/x86/amd/hsmp/plat.c
> @@ -10,14 +10,16 @@
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
>  #include <asm/amd_hsmp.h>
> -#include <asm/amd_nb.h>
>  
> +#include <linux/build_bug.h>
>  #include <linux/device.h>
>  #include <linux/module.h>
>  #include <linux/pci.h>
>  #include <linux/platform_device.h>
>  #include <linux/sysfs.h>
>  
> +#include <asm/amd_node.h>
> +
>  #include "hsmp.h"
>  
>  #define DRIVER_NAME		"amd_hsmp"
> @@ -34,28 +36,12 @@
>  #define SMN_HSMP_MSG_RESP	0x0010980
>  #define SMN_HSMP_MSG_DATA	0x00109E0
>  
> -#define HSMP_INDEX_REG		0xc4
> -#define HSMP_DATA_REG		0xc8
> -
>  static struct hsmp_plat_device *hsmp_pdev;
>  
>  static int amd_hsmp_pci_rdwr(struct hsmp_socket *sock, u32 offset,
>  			     u32 *value, bool write)
>  {
> -	int ret;
> -
> -	if (!sock->root)
> -		return -ENODEV;
> -
> -	ret = pci_write_config_dword(sock->root, HSMP_INDEX_REG,
> -				     sock->mbinfo.base_addr + offset);
> -	if (ret)
> -		return ret;
> -
> -	ret = (write ? pci_write_config_dword(sock->root, HSMP_DATA_REG, *value)
> -		     : pci_read_config_dword(sock->root, HSMP_DATA_REG, value));
> -
> -	return ret;
> +	return amd_smn_hsmp_rdwr(sock->sock_ind, sock->mbinfo.base_addr + offset, value, write);
>  }
>  
>  static ssize_t hsmp_metric_tbl_plat_read(struct file *filp, struct kobject *kobj,
> @@ -95,7 +81,12 @@ static umode_t hsmp_is_sock_attr_visible(struct kobject *kobj,
>   * Static array of 8 + 1(for NULL) elements is created below
>   * to create sysfs groups for sockets.
>   * is_bin_visible function is used to show / hide the necessary groups.
> + *
> + * Validate the maximum number against MAX_AMD_NUM_NODES. If this changes,
> + * then the attributes and groups below must be adjusted.
>   */
> +static_assert(MAX_AMD_NUM_NODES == 8);
> +
>  #define HSMP_BIN_ATTR(index, _list)					\
>  static const struct bin_attribute attr##index = {			\
>  	.attr = { .name = HSMP_METRICS_TABLE_NAME, .mode = 0444},	\
> @@ -159,10 +150,7 @@ static int init_platform_device(struct device *dev)
>  	int ret, i;
>  
>  	for (i = 0; i < hsmp_pdev->num_sockets; i++) {
> -		if (!node_to_amd_nb(i))
> -			return -ENODEV;
>  		sock = &hsmp_pdev->sock[i];
> -		sock->root			= node_to_amd_nb(i)->root;
>  		sock->sock_ind			= i;
>  		sock->dev			= dev;
>  		sock->mbinfo.base_addr		= SMN_HSMP_BASE;
> @@ -305,11 +293,11 @@ static int __init hsmp_plt_init(void)
>  		return -ENOMEM;
>  
>  	/*
> -	 * amd_nb_num() returns number of SMN/DF interfaces present in the system
> +	 * amd_num_nodes() returns number of SMN/DF interfaces present in the system
>  	 * if we have N SMN/DF interfaces that ideally means N sockets
>  	 */
> -	hsmp_pdev->num_sockets = amd_nb_num();
> -	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
> +	hsmp_pdev->num_sockets = amd_num_nodes();
> +	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
>  		return ret;
>  
>  	ret = platform_driver_register(&amd_hsmp_driver);

Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

-- 
 i.

[tip: x86/misc] x86/amd_node: Add support for debugfs access to SMN registers

[tip-bot2 for Mario Limonciello]

The following commit has been merged into the x86/misc branch of tip:

Commit-ID:     6b06755af6679fd7c98ebc017ac31c8a74127538
Gitweb:        https://git.kernel.org/tip/6b06755af6679fd7c98ebc017ac31c8a74127538
Author:        Mario Limonciello <mario.limonciello@amd.com>
AuthorDate:    Thu, 30 Jan 2025 19:48:57 
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 17 Feb 2025 10:09:56 +01:00

x86/amd_node: Add support for debugfs access to SMN registers

There are certain registers on AMD Zen systems that can only be accessed
through SMN.

Introduce a new interface that provides debugfs files for accessing SMN.  As
this introduces the capability for userspace to manipulate the hardware in
unpredictable ways, taint the kernel when writing.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250130-wip-x86-amd-nb-cleanup-v4-3-b5cc997e471b@amd.com
---
 arch/x86/kernel/amd_node.c |  99 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 99 insertions(+)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index ac57194..b670fa8 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -8,6 +8,7 @@
  * Author: Yazen Ghannam <Yazen.Ghannam@amd.com>
  */
 
+#include <linux/debugfs.h>
 #include <asm/amd_node.h>
 
 /*
@@ -192,6 +193,87 @@ int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write
 }
 EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
 
+static struct dentry *debugfs_dir;
+static u16 debug_node;
+static u32 debug_address;
+
+static ssize_t smn_node_write(struct file *file, const char __user *userbuf,
+			      size_t count, loff_t *ppos)
+{
+	u16 node;
+	int ret;
+
+	ret = kstrtou16_from_user(userbuf, count, 0, &node);
+	if (ret)
+		return ret;
+
+	if (node >= amd_num_nodes())
+		return -ENODEV;
+
+	debug_node = node;
+	return count;
+}
+
+static int smn_node_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "0x%08x\n", debug_node);
+	return 0;
+}
+
+static ssize_t smn_address_write(struct file *file, const char __user *userbuf,
+				 size_t count, loff_t *ppos)
+{
+	int ret;
+
+	ret = kstrtouint_from_user(userbuf, count, 0, &debug_address);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static int smn_address_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "0x%08x\n", debug_address);
+	return 0;
+}
+
+static int smn_value_show(struct seq_file *m, void *v)
+{
+	u32 val;
+	int ret;
+
+	ret = amd_smn_read(debug_node, debug_address, &val);
+	if (ret)
+		return ret;
+
+	seq_printf(m, "0x%08x\n", val);
+	return 0;
+}
+
+static ssize_t smn_value_write(struct file *file, const char __user *userbuf,
+			       size_t count, loff_t *ppos)
+{
+	u32 val;
+	int ret;
+
+	ret = kstrtouint_from_user(userbuf, count, 0, &val);
+	if (ret)
+		return ret;
+
+	add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
+
+	ret = amd_smn_write(debug_node, debug_address, val);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_node);
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_address);
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_value);
+
 static int amd_cache_roots(void)
 {
 	u16 node, num_nodes = amd_num_nodes();
@@ -239,6 +321,15 @@ static int reserve_root_config_spaces(void)
 	return 0;
 }
 
+static bool enable_dfs;
+
+static int __init amd_smn_enable_dfs(char *str)
+{
+	enable_dfs = true;
+	return 1;
+}
+__setup("amd_smn_debugfs_enable", amd_smn_enable_dfs);
+
 static int __init amd_smn_init(void)
 {
 	int err;
@@ -259,6 +350,14 @@ static int __init amd_smn_init(void)
 	if (err)
 		return err;
 
+	if (enable_dfs) {
+		debugfs_dir = debugfs_create_dir("amd_smn", arch_debugfs_dir);
+
+		debugfs_create_file("node",	0600, debugfs_dir, NULL, &smn_node_fops);
+		debugfs_create_file("address",	0600, debugfs_dir, NULL, &smn_address_fops);
+		debugfs_create_file("value",	0600, debugfs_dir, NULL, &smn_value_fops);
+	}
+
 	return 0;
 }
 

[tip: x86/misc] x86/amd_node: Add SMN offsets to exclusive region access

[tip-bot2 for Mario Limonciello]

The following commit has been merged into the x86/misc branch of tip:

Commit-ID:     bebe0afb74514ae51f4f348b28326c658b02209d
Gitweb:        https://git.kernel.org/tip/bebe0afb74514ae51f4f348b28326c658b02209d
Author:        Mario Limonciello <mario.limonciello@amd.com>
AuthorDate:    Thu, 30 Jan 2025 19:48:56 
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 17 Feb 2025 10:06:10 +01:00

x86/amd_node: Add SMN offsets to exclusive region access

Offsets 0x60 and 0x64 are used internally by kernel drivers that call
the amd_smn_read() and amd_smn_write() functions. If userspace accesses
the regions at the same time as the kernel it may cause malfunctions in
drivers using the offsets.

Add these offsets to the exclusions so that the kernel is tainted if a
non locked down userspace tries to access them.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250130-wip-x86-amd-nb-cleanup-v4-2-b5cc997e471b@amd.com
---
 arch/x86/kernel/amd_node.c | 41 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index 65045f2..ac57194 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -93,6 +93,7 @@ static struct pci_dev **amd_roots;
 
 /* Protect the PCI config register pairs used for SMN. */
 static DEFINE_MUTEX(smn_mutex);
+static bool smn_exclusive;
 
 #define SMN_INDEX_OFFSET	0x60
 #define SMN_DATA_OFFSET		0x64
@@ -149,6 +150,9 @@ static int __amd_smn_rw(u8 i_off, u8 d_off, u16 node, u32 address, u32 *value, b
 	if (!root)
 		return err;
 
+	if (!smn_exclusive)
+		return err;
+
 	guard(mutex)(&smn_mutex);
 
 	err = pci_write_config_dword(root, i_off, address);
@@ -202,6 +206,39 @@ static int amd_cache_roots(void)
 	return 0;
 }
 
+static int reserve_root_config_spaces(void)
+{
+	struct pci_dev *root = NULL;
+	struct pci_bus *bus = NULL;
+
+	while ((bus = pci_find_next_bus(bus))) {
+		/* Root device is Device 0 Function 0 on each Primary Bus. */
+		root = pci_get_slot(bus, 0);
+		if (!root)
+			continue;
+
+		if (root->vendor != PCI_VENDOR_ID_AMD &&
+		    root->vendor != PCI_VENDOR_ID_HYGON)
+			continue;
+
+		pci_dbg(root, "Reserving PCI config space\n");
+
+		/*
+		 * There are a few SMN index/data pairs and other registers
+		 * that shouldn't be accessed by user space.
+		 * So reserve the entire PCI config space for simplicity rather
+		 * than covering specific registers piecemeal.
+		 */
+		if (!pci_request_config_region_exclusive(root, 0, PCI_CFG_SPACE_SIZE, NULL)) {
+			pci_err(root, "Failed to reserve config space\n");
+			return -EEXIST;
+		}
+	}
+
+	smn_exclusive = true;
+	return 0;
+}
+
 static int __init amd_smn_init(void)
 {
 	int err;
@@ -218,6 +255,10 @@ static int __init amd_smn_init(void)
 	if (err)
 		return err;
 
+	err = reserve_root_config_spaces();
+	if (err)
+		return err;
+
 	return 0;
 }
 

[tip: x86/misc] x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD_NODE

[tip-bot2 for Yazen Ghannam]

The following commit has been merged into the x86/misc branch of tip:

Commit-ID:     735049b801cf3d597752017385cfc8768ce44303
Gitweb:        https://git.kernel.org/tip/735049b801cf3d597752017385cfc8768ce44303
Author:        Yazen Ghannam <yazen.ghannam@amd.com>
AuthorDate:    Thu, 30 Jan 2025 19:48:55 
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 17 Feb 2025 09:47:31 +01:00

x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD_NODE

The HSMP interface is just an SMN interface with different offsets.

Define an HSMP wrapper in the SMN code and have the HSMP platform driver
use that rather than a local solution.

Also, remove the "root" member from AMD_NB, since there are no more
users of it.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Carlos Bilbao <carlos.bilbao@kernel.org>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250130-wip-x86-amd-nb-cleanup-v4-1-b5cc997e471b@amd.com
---
 arch/x86/include/asm/amd_nb.h         |  1 +-
 arch/x86/include/asm/amd_node.h       | 13 +++++++++-
 arch/x86/kernel/amd_nb.c              |  1 +-
 arch/x86/kernel/amd_node.c            |  9 +++++++-
 drivers/platform/x86/amd/hsmp/Kconfig |  2 +-
 drivers/platform/x86/amd/hsmp/acpi.c  |  7 ++---
 drivers/platform/x86/amd/hsmp/hsmp.c  |  1 +-
 drivers/platform/x86/amd/hsmp/hsmp.h  |  3 +--
 drivers/platform/x86/amd/hsmp/plat.c  | 36 ++++++++------------------
 9 files changed, 39 insertions(+), 34 deletions(-)

diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
index 4c4efb9..adfa085 100644
--- a/arch/x86/include/asm/amd_nb.h
+++ b/arch/x86/include/asm/amd_nb.h
@@ -27,7 +27,6 @@ struct amd_l3_cache {
 };
 
 struct amd_northbridge {
-	struct pci_dev *root;
 	struct pci_dev *misc;
 	struct pci_dev *link;
 	struct amd_l3_cache l3_cache;
diff --git a/arch/x86/include/asm/amd_node.h b/arch/x86/include/asm/amd_node.h
index 113ad3e..002c3af 100644
--- a/arch/x86/include/asm/amd_node.h
+++ b/arch/x86/include/asm/amd_node.h
@@ -30,7 +30,20 @@ static inline u16 amd_num_nodes(void)
 	return topology_amd_nodes_per_pkg() * topology_max_packages();
 }
 
+#ifdef CONFIG_AMD_NODE
 int __must_check amd_smn_read(u16 node, u32 address, u32 *value);
 int __must_check amd_smn_write(u16 node, u32 address, u32 value);
 
+/* Should only be used by the HSMP driver. */
+int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write);
+#else
+static inline int __must_check amd_smn_read(u16 node, u32 address, u32 *value) { return -ENODEV; }
+static inline int __must_check amd_smn_write(u16 node, u32 address, u32 value) { return -ENODEV; }
+
+static inline int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_AMD_NODE */
+
 #endif /*_ASM_X86_AMD_NODE_H_*/
diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index 11fac09..24d7a87 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -73,7 +73,6 @@ static int amd_cache_northbridges(void)
 	amd_northbridges.nb = nb;
 
 	for (i = 0; i < amd_northbridges.num; i++) {
-		node_to_amd_nb(i)->root = amd_node_get_root(i);
 		node_to_amd_nb(i)->misc = amd_node_get_func(i, 3);
 
 		/*
diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index d2ec7fd..65045f2 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -97,6 +97,9 @@ static DEFINE_MUTEX(smn_mutex);
 #define SMN_INDEX_OFFSET	0x60
 #define SMN_DATA_OFFSET		0x64
 
+#define HSMP_INDEX_OFFSET	0xc4
+#define HSMP_DATA_OFFSET	0xc8
+
 /*
  * SMN accesses may fail in ways that are difficult to detect here in the called
  * functions amd_smn_read() and amd_smn_write(). Therefore, callers must do
@@ -179,6 +182,12 @@ int __must_check amd_smn_write(u16 node, u32 address, u32 value)
 }
 EXPORT_SYMBOL_GPL(amd_smn_write);
 
+int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
+{
+	return __amd_smn_rw(HSMP_INDEX_OFFSET, HSMP_DATA_OFFSET, node, address, value, write);
+}
+EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
+
 static int amd_cache_roots(void)
 {
 	u16 node, num_nodes = amd_num_nodes();
diff --git a/drivers/platform/x86/amd/hsmp/Kconfig b/drivers/platform/x86/amd/hsmp/Kconfig
index 7d10d44..d6f7a62 100644
--- a/drivers/platform/x86/amd/hsmp/Kconfig
+++ b/drivers/platform/x86/amd/hsmp/Kconfig
@@ -7,7 +7,7 @@ config AMD_HSMP
 	tristate
 
 menu "AMD HSMP Driver"
-	depends on AMD_NB || COMPILE_TEST
+	depends on AMD_NODE || COMPILE_TEST
 
 config AMD_HSMP_ACPI
 	tristate "AMD HSMP ACPI device driver"
diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
index 444b43b..c1eccb3 100644
--- a/drivers/platform/x86/amd/hsmp/acpi.c
+++ b/drivers/platform/x86/amd/hsmp/acpi.c
@@ -10,7 +10,6 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
 #include <linux/acpi.h>
 #include <linux/device.h>
@@ -24,6 +23,8 @@
 
 #include <uapi/asm-generic/errno-base.h>
 
+#include <asm/amd_node.h>
+
 #include "hsmp.h"
 
 #define DRIVER_NAME		"amd_hsmp"
@@ -321,8 +322,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	if (!hsmp_pdev->is_probed) {
-		hsmp_pdev->num_sockets = amd_nb_num();
-		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
+		hsmp_pdev->num_sockets = amd_num_nodes();
+		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
 			return -ENODEV;
 
 		hsmp_pdev->sock = devm_kcalloc(&pdev->dev, hsmp_pdev->num_sockets,
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c
index 03164e3..a3ac09a 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.c
+++ b/drivers/platform/x86/amd/hsmp/hsmp.c
@@ -8,7 +8,6 @@
  */
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
 #include <linux/acpi.h>
 #include <linux/delay.h>
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
index e852f0a..af8b21f 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.h
+++ b/drivers/platform/x86/amd/hsmp/hsmp.h
@@ -21,8 +21,6 @@
 
 #define HSMP_ATTR_GRP_NAME_SIZE	10
 
-#define MAX_AMD_SOCKETS 8
-
 #define HSMP_CDEV_NAME		"hsmp_cdev"
 #define HSMP_DEVNODE_NAME	"hsmp"
 
@@ -41,7 +39,6 @@ struct hsmp_socket {
 	void __iomem *virt_base_addr;
 	struct semaphore hsmp_sem;
 	char name[HSMP_ATTR_GRP_NAME_SIZE];
-	struct pci_dev *root;
 	struct device *dev;
 	u16 sock_ind;
 	int (*amd_hsmp_rdwr)(struct hsmp_socket *sock, u32 off, u32 *val, bool rw);
diff --git a/drivers/platform/x86/amd/hsmp/plat.c b/drivers/platform/x86/amd/hsmp/plat.c
index 02ca857..b9782a0 100644
--- a/drivers/platform/x86/amd/hsmp/plat.c
+++ b/drivers/platform/x86/amd/hsmp/plat.c
@@ -10,14 +10,16 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
+#include <linux/build_bug.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/sysfs.h>
 
+#include <asm/amd_node.h>
+
 #include "hsmp.h"
 
 #define DRIVER_NAME		"amd_hsmp"
@@ -34,28 +36,12 @@
 #define SMN_HSMP_MSG_RESP	0x0010980
 #define SMN_HSMP_MSG_DATA	0x00109E0
 
-#define HSMP_INDEX_REG		0xc4
-#define HSMP_DATA_REG		0xc8
-
 static struct hsmp_plat_device *hsmp_pdev;
 
 static int amd_hsmp_pci_rdwr(struct hsmp_socket *sock, u32 offset,
 			     u32 *value, bool write)
 {
-	int ret;
-
-	if (!sock->root)
-		return -ENODEV;
-
-	ret = pci_write_config_dword(sock->root, HSMP_INDEX_REG,
-				     sock->mbinfo.base_addr + offset);
-	if (ret)
-		return ret;
-
-	ret = (write ? pci_write_config_dword(sock->root, HSMP_DATA_REG, *value)
-		     : pci_read_config_dword(sock->root, HSMP_DATA_REG, value));
-
-	return ret;
+	return amd_smn_hsmp_rdwr(sock->sock_ind, sock->mbinfo.base_addr + offset, value, write);
 }
 
 static ssize_t hsmp_metric_tbl_plat_read(struct file *filp, struct kobject *kobj,
@@ -95,7 +81,12 @@ static umode_t hsmp_is_sock_attr_visible(struct kobject *kobj,
  * Static array of 8 + 1(for NULL) elements is created below
  * to create sysfs groups for sockets.
  * is_bin_visible function is used to show / hide the necessary groups.
+ *
+ * Validate the maximum number against MAX_AMD_NUM_NODES. If this changes,
+ * then the attributes and groups below must be adjusted.
  */
+static_assert(MAX_AMD_NUM_NODES == 8);
+
 #define HSMP_BIN_ATTR(index, _list)					\
 static const struct bin_attribute attr##index = {			\
 	.attr = { .name = HSMP_METRICS_TABLE_NAME, .mode = 0444},	\
@@ -159,10 +150,7 @@ static int init_platform_device(struct device *dev)
 	int ret, i;
 
 	for (i = 0; i < hsmp_pdev->num_sockets; i++) {
-		if (!node_to_amd_nb(i))
-			return -ENODEV;
 		sock = &hsmp_pdev->sock[i];
-		sock->root			= node_to_amd_nb(i)->root;
 		sock->sock_ind			= i;
 		sock->dev			= dev;
 		sock->mbinfo.base_addr		= SMN_HSMP_BASE;
@@ -305,11 +293,11 @@ static int __init hsmp_plt_init(void)
 		return -ENOMEM;
 
 	/*
-	 * amd_nb_num() returns number of SMN/DF interfaces present in the system
+	 * amd_num_nodes() returns number of SMN/DF interfaces present in the system
 	 * if we have N SMN/DF interfaces that ideally means N sockets
 	 */
-	hsmp_pdev->num_sockets = amd_nb_num();
-	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
+	hsmp_pdev->num_sockets = amd_num_nodes();
+	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
 		return ret;
 
 	ret = platform_driver_register(&amd_hsmp_driver);

[tip: x86/core] x86/amd_node: Add SMN offsets to exclusive region access

[tip-bot2 for Mario Limonciello]

The following commit has been merged into the x86/core branch of tip:

Commit-ID:     83518453074d1f3eadbf7e61652b608a60087317
Gitweb:        https://git.kernel.org/tip/83518453074d1f3eadbf7e61652b608a60087317
Author:        Mario Limonciello <mario.limonciello@amd.com>
AuthorDate:    Thu, 30 Jan 2025 19:48:56 
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 19 Mar 2025 11:18:23 +01:00

x86/amd_node: Add SMN offsets to exclusive region access

Offsets 0x60 and 0x64 are used internally by kernel drivers that call
the amd_smn_read() and amd_smn_write() functions. If userspace accesses
the regions at the same time as the kernel it may cause malfunctions in
drivers using the offsets.

Add these offsets to the exclusions so that the kernel is tainted if a
non locked down userspace tries to access them.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250130-wip-x86-amd-nb-cleanup-v4-2-b5cc997e471b@amd.com
---
 arch/x86/kernel/amd_node.c | 41 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index 65045f2..ac57194 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -93,6 +93,7 @@ static struct pci_dev **amd_roots;
 
 /* Protect the PCI config register pairs used for SMN. */
 static DEFINE_MUTEX(smn_mutex);
+static bool smn_exclusive;
 
 #define SMN_INDEX_OFFSET	0x60
 #define SMN_DATA_OFFSET		0x64
@@ -149,6 +150,9 @@ static int __amd_smn_rw(u8 i_off, u8 d_off, u16 node, u32 address, u32 *value, b
 	if (!root)
 		return err;
 
+	if (!smn_exclusive)
+		return err;
+
 	guard(mutex)(&smn_mutex);
 
 	err = pci_write_config_dword(root, i_off, address);
@@ -202,6 +206,39 @@ static int amd_cache_roots(void)
 	return 0;
 }
 
+static int reserve_root_config_spaces(void)
+{
+	struct pci_dev *root = NULL;
+	struct pci_bus *bus = NULL;
+
+	while ((bus = pci_find_next_bus(bus))) {
+		/* Root device is Device 0 Function 0 on each Primary Bus. */
+		root = pci_get_slot(bus, 0);
+		if (!root)
+			continue;
+
+		if (root->vendor != PCI_VENDOR_ID_AMD &&
+		    root->vendor != PCI_VENDOR_ID_HYGON)
+			continue;
+
+		pci_dbg(root, "Reserving PCI config space\n");
+
+		/*
+		 * There are a few SMN index/data pairs and other registers
+		 * that shouldn't be accessed by user space.
+		 * So reserve the entire PCI config space for simplicity rather
+		 * than covering specific registers piecemeal.
+		 */
+		if (!pci_request_config_region_exclusive(root, 0, PCI_CFG_SPACE_SIZE, NULL)) {
+			pci_err(root, "Failed to reserve config space\n");
+			return -EEXIST;
+		}
+	}
+
+	smn_exclusive = true;
+	return 0;
+}
+
 static int __init amd_smn_init(void)
 {
 	int err;
@@ -218,6 +255,10 @@ static int __init amd_smn_init(void)
 	if (err)
 		return err;
 
+	err = reserve_root_config_spaces();
+	if (err)
+		return err;
+
 	return 0;
 }
 

[tip: x86/core] x86/amd_node: Add support for debugfs access to SMN registers

[tip-bot2 for Mario Limonciello]

The following commit has been merged into the x86/core branch of tip:

Commit-ID:     9c19cc1f5f571b03cc56338ed12836531a4989a4
Gitweb:        https://git.kernel.org/tip/9c19cc1f5f571b03cc56338ed12836531a4989a4
Author:        Mario Limonciello <mario.limonciello@amd.com>
AuthorDate:    Thu, 30 Jan 2025 19:48:57 
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 19 Mar 2025 11:18:33 +01:00

x86/amd_node: Add support for debugfs access to SMN registers

There are certain registers on AMD Zen systems that can only be accessed
through SMN.

Introduce a new interface that provides debugfs files for accessing SMN.  As
this introduces the capability for userspace to manipulate the hardware in
unpredictable ways, taint the kernel when writing.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250130-wip-x86-amd-nb-cleanup-v4-3-b5cc997e471b@amd.com
---
 arch/x86/kernel/amd_node.c |  99 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 99 insertions(+)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index ac57194..b670fa8 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -8,6 +8,7 @@
  * Author: Yazen Ghannam <Yazen.Ghannam@amd.com>
  */
 
+#include <linux/debugfs.h>
 #include <asm/amd_node.h>
 
 /*
@@ -192,6 +193,87 @@ int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write
 }
 EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
 
+static struct dentry *debugfs_dir;
+static u16 debug_node;
+static u32 debug_address;
+
+static ssize_t smn_node_write(struct file *file, const char __user *userbuf,
+			      size_t count, loff_t *ppos)
+{
+	u16 node;
+	int ret;
+
+	ret = kstrtou16_from_user(userbuf, count, 0, &node);
+	if (ret)
+		return ret;
+
+	if (node >= amd_num_nodes())
+		return -ENODEV;
+
+	debug_node = node;
+	return count;
+}
+
+static int smn_node_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "0x%08x\n", debug_node);
+	return 0;
+}
+
+static ssize_t smn_address_write(struct file *file, const char __user *userbuf,
+				 size_t count, loff_t *ppos)
+{
+	int ret;
+
+	ret = kstrtouint_from_user(userbuf, count, 0, &debug_address);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static int smn_address_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "0x%08x\n", debug_address);
+	return 0;
+}
+
+static int smn_value_show(struct seq_file *m, void *v)
+{
+	u32 val;
+	int ret;
+
+	ret = amd_smn_read(debug_node, debug_address, &val);
+	if (ret)
+		return ret;
+
+	seq_printf(m, "0x%08x\n", val);
+	return 0;
+}
+
+static ssize_t smn_value_write(struct file *file, const char __user *userbuf,
+			       size_t count, loff_t *ppos)
+{
+	u32 val;
+	int ret;
+
+	ret = kstrtouint_from_user(userbuf, count, 0, &val);
+	if (ret)
+		return ret;
+
+	add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
+
+	ret = amd_smn_write(debug_node, debug_address, val);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_node);
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_address);
+DEFINE_SHOW_STORE_ATTRIBUTE(smn_value);
+
 static int amd_cache_roots(void)
 {
 	u16 node, num_nodes = amd_num_nodes();
@@ -239,6 +321,15 @@ static int reserve_root_config_spaces(void)
 	return 0;
 }
 
+static bool enable_dfs;
+
+static int __init amd_smn_enable_dfs(char *str)
+{
+	enable_dfs = true;
+	return 1;
+}
+__setup("amd_smn_debugfs_enable", amd_smn_enable_dfs);
+
 static int __init amd_smn_init(void)
 {
 	int err;
@@ -259,6 +350,14 @@ static int __init amd_smn_init(void)
 	if (err)
 		return err;
 
+	if (enable_dfs) {
+		debugfs_dir = debugfs_create_dir("amd_smn", arch_debugfs_dir);
+
+		debugfs_create_file("node",	0600, debugfs_dir, NULL, &smn_node_fops);
+		debugfs_create_file("address",	0600, debugfs_dir, NULL, &smn_address_fops);
+		debugfs_create_file("value",	0600, debugfs_dir, NULL, &smn_value_fops);
+	}
+
 	return 0;
 }
 

[tip: x86/core] x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD_NODE

[tip-bot2 for Yazen Ghannam]

The following commit has been merged into the x86/core branch of tip:

Commit-ID:     8a3dc0f7c4ccf13098dba804be06799b4bd46c7a
Gitweb:        https://git.kernel.org/tip/8a3dc0f7c4ccf13098dba804be06799b4bd46c7a
Author:        Yazen Ghannam <yazen.ghannam@amd.com>
AuthorDate:    Thu, 30 Jan 2025 19:48:55 
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 19 Mar 2025 11:18:05 +01:00

x86/amd_node, platform/x86/amd/hsmp: Have HSMP use SMN through AMD_NODE

The HSMP interface is just an SMN interface with different offsets.

Define an HSMP wrapper in the SMN code and have the HSMP platform driver
use that rather than a local solution.

Also, remove the "root" member from AMD_NB, since there are no more
users of it.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Carlos Bilbao <carlos.bilbao@kernel.org>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250130-wip-x86-amd-nb-cleanup-v4-1-b5cc997e471b@amd.com
---
 arch/x86/include/asm/amd_nb.h         |  1 +-
 arch/x86/include/asm/amd_node.h       | 13 +++++++++-
 arch/x86/kernel/amd_nb.c              |  1 +-
 arch/x86/kernel/amd_node.c            |  9 +++++++-
 drivers/platform/x86/amd/hsmp/Kconfig |  2 +-
 drivers/platform/x86/amd/hsmp/acpi.c  |  7 ++---
 drivers/platform/x86/amd/hsmp/hsmp.c  |  1 +-
 drivers/platform/x86/amd/hsmp/hsmp.h  |  3 +--
 drivers/platform/x86/amd/hsmp/plat.c  | 36 ++++++++------------------
 9 files changed, 39 insertions(+), 34 deletions(-)

diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h
index 4c4efb9..adfa085 100644
--- a/arch/x86/include/asm/amd_nb.h
+++ b/arch/x86/include/asm/amd_nb.h
@@ -27,7 +27,6 @@ struct amd_l3_cache {
 };
 
 struct amd_northbridge {
-	struct pci_dev *root;
 	struct pci_dev *misc;
 	struct pci_dev *link;
 	struct amd_l3_cache l3_cache;
diff --git a/arch/x86/include/asm/amd_node.h b/arch/x86/include/asm/amd_node.h
index 113ad3e..002c3af 100644
--- a/arch/x86/include/asm/amd_node.h
+++ b/arch/x86/include/asm/amd_node.h
@@ -30,7 +30,20 @@ static inline u16 amd_num_nodes(void)
 	return topology_amd_nodes_per_pkg() * topology_max_packages();
 }
 
+#ifdef CONFIG_AMD_NODE
 int __must_check amd_smn_read(u16 node, u32 address, u32 *value);
 int __must_check amd_smn_write(u16 node, u32 address, u32 value);
 
+/* Should only be used by the HSMP driver. */
+int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write);
+#else
+static inline int __must_check amd_smn_read(u16 node, u32 address, u32 *value) { return -ENODEV; }
+static inline int __must_check amd_smn_write(u16 node, u32 address, u32 value) { return -ENODEV; }
+
+static inline int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_AMD_NODE */
+
 #endif /*_ASM_X86_AMD_NODE_H_*/
diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index 67e7737..6d12a9b 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -73,7 +73,6 @@ static int amd_cache_northbridges(void)
 	amd_northbridges.nb = nb;
 
 	for (i = 0; i < amd_northbridges.num; i++) {
-		node_to_amd_nb(i)->root = amd_node_get_root(i);
 		node_to_amd_nb(i)->misc = amd_node_get_func(i, 3);
 
 		/*
diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index d2ec7fd..65045f2 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -97,6 +97,9 @@ static DEFINE_MUTEX(smn_mutex);
 #define SMN_INDEX_OFFSET	0x60
 #define SMN_DATA_OFFSET		0x64
 
+#define HSMP_INDEX_OFFSET	0xc4
+#define HSMP_DATA_OFFSET	0xc8
+
 /*
  * SMN accesses may fail in ways that are difficult to detect here in the called
  * functions amd_smn_read() and amd_smn_write(). Therefore, callers must do
@@ -179,6 +182,12 @@ int __must_check amd_smn_write(u16 node, u32 address, u32 value)
 }
 EXPORT_SYMBOL_GPL(amd_smn_write);
 
+int __must_check amd_smn_hsmp_rdwr(u16 node, u32 address, u32 *value, bool write)
+{
+	return __amd_smn_rw(HSMP_INDEX_OFFSET, HSMP_DATA_OFFSET, node, address, value, write);
+}
+EXPORT_SYMBOL_GPL(amd_smn_hsmp_rdwr);
+
 static int amd_cache_roots(void)
 {
 	u16 node, num_nodes = amd_num_nodes();
diff --git a/drivers/platform/x86/amd/hsmp/Kconfig b/drivers/platform/x86/amd/hsmp/Kconfig
index 7d10d44..d6f7a62 100644
--- a/drivers/platform/x86/amd/hsmp/Kconfig
+++ b/drivers/platform/x86/amd/hsmp/Kconfig
@@ -7,7 +7,7 @@ config AMD_HSMP
 	tristate
 
 menu "AMD HSMP Driver"
-	depends on AMD_NB || COMPILE_TEST
+	depends on AMD_NODE || COMPILE_TEST
 
 config AMD_HSMP_ACPI
 	tristate "AMD HSMP ACPI device driver"
diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
index 444b43b..c1eccb3 100644
--- a/drivers/platform/x86/amd/hsmp/acpi.c
+++ b/drivers/platform/x86/amd/hsmp/acpi.c
@@ -10,7 +10,6 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
 #include <linux/acpi.h>
 #include <linux/device.h>
@@ -24,6 +23,8 @@
 
 #include <uapi/asm-generic/errno-base.h>
 
+#include <asm/amd_node.h>
+
 #include "hsmp.h"
 
 #define DRIVER_NAME		"amd_hsmp"
@@ -321,8 +322,8 @@ static int hsmp_acpi_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	if (!hsmp_pdev->is_probed) {
-		hsmp_pdev->num_sockets = amd_nb_num();
-		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
+		hsmp_pdev->num_sockets = amd_num_nodes();
+		if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
 			return -ENODEV;
 
 		hsmp_pdev->sock = devm_kcalloc(&pdev->dev, hsmp_pdev->num_sockets,
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c
index 03164e3..a3ac09a 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.c
+++ b/drivers/platform/x86/amd/hsmp/hsmp.c
@@ -8,7 +8,6 @@
  */
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
 #include <linux/acpi.h>
 #include <linux/delay.h>
diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
index e852f0a..af8b21f 100644
--- a/drivers/platform/x86/amd/hsmp/hsmp.h
+++ b/drivers/platform/x86/amd/hsmp/hsmp.h
@@ -21,8 +21,6 @@
 
 #define HSMP_ATTR_GRP_NAME_SIZE	10
 
-#define MAX_AMD_SOCKETS 8
-
 #define HSMP_CDEV_NAME		"hsmp_cdev"
 #define HSMP_DEVNODE_NAME	"hsmp"
 
@@ -41,7 +39,6 @@ struct hsmp_socket {
 	void __iomem *virt_base_addr;
 	struct semaphore hsmp_sem;
 	char name[HSMP_ATTR_GRP_NAME_SIZE];
-	struct pci_dev *root;
 	struct device *dev;
 	u16 sock_ind;
 	int (*amd_hsmp_rdwr)(struct hsmp_socket *sock, u32 off, u32 *val, bool rw);
diff --git a/drivers/platform/x86/amd/hsmp/plat.c b/drivers/platform/x86/amd/hsmp/plat.c
index 02ca857..b9782a0 100644
--- a/drivers/platform/x86/amd/hsmp/plat.c
+++ b/drivers/platform/x86/amd/hsmp/plat.c
@@ -10,14 +10,16 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <asm/amd_hsmp.h>
-#include <asm/amd_nb.h>
 
+#include <linux/build_bug.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/sysfs.h>
 
+#include <asm/amd_node.h>
+
 #include "hsmp.h"
 
 #define DRIVER_NAME		"amd_hsmp"
@@ -34,28 +36,12 @@
 #define SMN_HSMP_MSG_RESP	0x0010980
 #define SMN_HSMP_MSG_DATA	0x00109E0
 
-#define HSMP_INDEX_REG		0xc4
-#define HSMP_DATA_REG		0xc8
-
 static struct hsmp_plat_device *hsmp_pdev;
 
 static int amd_hsmp_pci_rdwr(struct hsmp_socket *sock, u32 offset,
 			     u32 *value, bool write)
 {
-	int ret;
-
-	if (!sock->root)
-		return -ENODEV;
-
-	ret = pci_write_config_dword(sock->root, HSMP_INDEX_REG,
-				     sock->mbinfo.base_addr + offset);
-	if (ret)
-		return ret;
-
-	ret = (write ? pci_write_config_dword(sock->root, HSMP_DATA_REG, *value)
-		     : pci_read_config_dword(sock->root, HSMP_DATA_REG, value));
-
-	return ret;
+	return amd_smn_hsmp_rdwr(sock->sock_ind, sock->mbinfo.base_addr + offset, value, write);
 }
 
 static ssize_t hsmp_metric_tbl_plat_read(struct file *filp, struct kobject *kobj,
@@ -95,7 +81,12 @@ static umode_t hsmp_is_sock_attr_visible(struct kobject *kobj,
  * Static array of 8 + 1(for NULL) elements is created below
  * to create sysfs groups for sockets.
  * is_bin_visible function is used to show / hide the necessary groups.
+ *
+ * Validate the maximum number against MAX_AMD_NUM_NODES. If this changes,
+ * then the attributes and groups below must be adjusted.
  */
+static_assert(MAX_AMD_NUM_NODES == 8);
+
 #define HSMP_BIN_ATTR(index, _list)					\
 static const struct bin_attribute attr##index = {			\
 	.attr = { .name = HSMP_METRICS_TABLE_NAME, .mode = 0444},	\
@@ -159,10 +150,7 @@ static int init_platform_device(struct device *dev)
 	int ret, i;
 
 	for (i = 0; i < hsmp_pdev->num_sockets; i++) {
-		if (!node_to_amd_nb(i))
-			return -ENODEV;
 		sock = &hsmp_pdev->sock[i];
-		sock->root			= node_to_amd_nb(i)->root;
 		sock->sock_ind			= i;
 		sock->dev			= dev;
 		sock->mbinfo.base_addr		= SMN_HSMP_BASE;
@@ -305,11 +293,11 @@ static int __init hsmp_plt_init(void)
 		return -ENOMEM;
 
 	/*
-	 * amd_nb_num() returns number of SMN/DF interfaces present in the system
+	 * amd_num_nodes() returns number of SMN/DF interfaces present in the system
 	 * if we have N SMN/DF interfaces that ideally means N sockets
 	 */
-	hsmp_pdev->num_sockets = amd_nb_num();
-	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_SOCKETS)
+	hsmp_pdev->num_sockets = amd_num_nodes();
+	if (hsmp_pdev->num_sockets == 0 || hsmp_pdev->num_sockets > MAX_AMD_NUM_NODES)
 		return ret;
 
 	ret = platform_driver_register(&amd_hsmp_driver);