Merge tag 'x86-urgent-2025-11-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:

 - Fix AMD PCI root device caching regression that triggers
   on certain firmware variants

 - Fix the zen5_rdseed_microcode[] array to be NULL-terminated

 - Add more AMD models to microcode signature checking

* tag 'x86-urgent-2025-11-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/microcode/AMD: Add more known models to entry sign checking
  x86/CPU/AMD: Add missing terminator for zen5_rdseed_microcode
  x86/amd_node: Fix AMD root device caching

Author: torvalds

arch/x86/include/asm/amd/node.h

@@ -23,7 +23,6 @@
 #define AMD_NODE0_PCI_SLOT	0x18
 
 struct pci_dev *amd_node_get_func(u16 node, u8 func);
-struct pci_dev *amd_node_get_root(u16 node);
 
 static inline u16 amd_num_nodes(void)
 {

arch/x86/kernel/amd_node.c

@@ -34,62 +34,6 @@ struct pci_dev *amd_node_get_func(u16 node, u8 func)
 	return pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(AMD_NODE0_PCI_SLOT + node, func));
 }
 
-#define DF_BLK_INST_CNT		0x040
-#define	DF_CFG_ADDR_CNTL_LEGACY	0x084
-#define	DF_CFG_ADDR_CNTL_DF4	0xC04
-
-#define DF_MAJOR_REVISION	GENMASK(27, 24)
-
-static u16 get_cfg_addr_cntl_offset(struct pci_dev *df_f0)
-{
-	u32 reg;
-
-	/*
-	 * Revision fields added for DF4 and later.
-	 *
-	 * Major revision of '0' is found pre-DF4. Field is Read-as-Zero.
-	 */
-	if (pci_read_config_dword(df_f0, DF_BLK_INST_CNT, &reg))
-		return 0;
-
-	if (reg & DF_MAJOR_REVISION)
-		return DF_CFG_ADDR_CNTL_DF4;
-
-	return DF_CFG_ADDR_CNTL_LEGACY;
-}
-
-struct pci_dev *amd_node_get_root(u16 node)
-{
-	struct pci_dev *root;
-	u16 cntl_off;
-	u8 bus;
-
-	if (!cpu_feature_enabled(X86_FEATURE_ZEN))
-		return NULL;
-
-	/*
-	 * D18F0xXXX [Config Address Control] (DF::CfgAddressCntl)
-	 * Bits [7:0] (SecBusNum) holds the bus number of the root device for
-	 * this Data Fabric instance. The segment, device, and function will be 0.
-	 */
-	struct pci_dev *df_f0 __free(pci_dev_put) = amd_node_get_func(node, 0);
-	if (!df_f0)
-		return NULL;
-
-	cntl_off = get_cfg_addr_cntl_offset(df_f0);
-	if (!cntl_off)
-		return NULL;
-
-	if (pci_read_config_byte(df_f0, cntl_off, &bus))
-		return NULL;
-
-	/* Grab the pointer for the actual root device instance. */
-	root = pci_get_domain_bus_and_slot(0, bus, 0);
-
-	pci_dbg(root, "is root for AMD node %u\n", node);
-	return root;
-}
-
 static struct pci_dev **amd_roots;
 
 /* Protect the PCI config register pairs used for SMN. */
@@ -274,51 +218,21 @@ 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();
-
-	amd_roots = kcalloc(num_nodes, sizeof(*amd_roots), GFP_KERNEL);
-	if (!amd_roots)
-		return -ENOMEM;
-
-	for (node = 0; node < num_nodes; node++)
-		amd_roots[node] = amd_node_get_root(node);
-
-	return 0;
-}
-
-static int reserve_root_config_spaces(void)
+static struct pci_dev *get_next_root(struct pci_dev *root)
 {
-	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)
+	while ((root = pci_get_class(PCI_CLASS_BRIDGE_HOST << 8, root))) {
+		/* Root device is Device 0 Function 0. */
+		if (root->devfn)
 			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;
-		}
+		break;
 	}
 
-	smn_exclusive = true;
-	return 0;
+	return root;
 }
 
 static bool enable_dfs;
@@ -332,7 +246,8 @@ __setup("amd_smn_debugfs_enable", amd_smn_enable_dfs);
 
 static int __init amd_smn_init(void)
 {
-	int err;
+	u16 count, num_roots, roots_per_node, node, num_nodes;
+	struct pci_dev *root;
 
 	if (!cpu_feature_enabled(X86_FEATURE_ZEN))
 		return 0;
@@ -342,13 +257,48 @@ static int __init amd_smn_init(void)
 	if (amd_roots)
 		return 0;
 
-	err = amd_cache_roots();
-	if (err)
-		return err;
+	num_roots = 0;
+	root = NULL;
+	while ((root = get_next_root(root))) {
+		pci_dbg(root, "Reserving PCI config space\n");
 
-	err = reserve_root_config_spaces();
-	if (err)
-		return err;
+		/*
+		 * 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;
+		}
+
+		num_roots++;
+	}
+
+	pr_debug("Found %d AMD root devices\n", num_roots);
+
+	if (!num_roots)
+		return -ENODEV;
+
+	num_nodes = amd_num_nodes();
+	amd_roots = kcalloc(num_nodes, sizeof(*amd_roots), GFP_KERNEL);
+	if (!amd_roots)
+		return -ENOMEM;
+
+	roots_per_node = num_roots / num_nodes;
+
+	count = 0;
+	node = 0;
+	root = NULL;
+	while (node < num_nodes && (root = get_next_root(root))) {
+		/* Use one root for each node and skip the rest. */
+		if (count++ % roots_per_node)
+			continue;
+
+		pci_dbg(root, "is root for AMD node %u\n", node);
+		amd_roots[node++] = root;
+	}
 
 	if (enable_dfs) {
 		debugfs_dir = debugfs_create_dir("amd_smn", arch_debugfs_dir);
@@ -358,6 +308,8 @@ static int __init amd_smn_init(void)
 		debugfs_create_file("value",	0600, debugfs_dir, NULL, &smn_value_fops);
 	}
 
+	smn_exclusive = true;
+
 	return 0;
 }
 

arch/x86/kernel/cpu/amd.c

@@ -1038,6 +1038,7 @@ static void init_amd_zen4(struct cpuinfo_x86 *c)
 static const struct x86_cpu_id zen5_rdseed_microcode[] = {
 	ZEN_MODEL_STEP_UCODE(0x1a, 0x02, 0x1, 0x0b00215a),
 	ZEN_MODEL_STEP_UCODE(0x1a, 0x11, 0x0, 0x0b101054),
+	{},
 };
 
 static void init_amd_zen5(struct cpuinfo_x86 *c)

arch/x86/kernel/cpu/microcode/amd.c

@@ -220,10 +220,12 @@ static bool need_sha_check(u32 cur_rev)
 	case 0xaa001: return cur_rev <= 0xaa00116; break;
 	case 0xaa002: return cur_rev <= 0xaa00218; break;
 	case 0xb0021: return cur_rev <= 0xb002146; break;
+	case 0xb0081: return cur_rev <= 0xb008111; break;
 	case 0xb1010: return cur_rev <= 0xb101046; break;
 	case 0xb2040: return cur_rev <= 0xb204031; break;
 	case 0xb4040: return cur_rev <= 0xb404031; break;
 	case 0xb6000: return cur_rev <= 0xb600031; break;
+	case 0xb6080: return cur_rev <= 0xb608031; break;
 	case 0xb7000: return cur_rev <= 0xb700031; break;
 	default: break;
 	}