linux-kernel - [PATCH v2 12/16] x86/amd_node: Remove dependency on AMD

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Message-ID: <20241206161210.163701-13-yazen.ghannam@amd.com>
Date: Fri, 6 Dec 2024 16:12:05 +0000
From: Yazen Ghannam <yazen.ghannam@....com>
To: <yazen.ghannam@....com>, <x86@...nel.org>, Tony Luck
	<tony.luck@...el.com>, Mario Limonciello <mario.limonciello@....com>, "Bjorn
 Helgaas" <bhelgaas@...gle.com>, Jean Delvare <jdelvare@...e.com>, "Guenter
 Roeck" <linux@...ck-us.net>, Clemens Ladisch <clemens@...isch.de>, "Shyam
 Sundar S K" <Shyam-sundar.S-k@....com>, Hans de Goede <hdegoede@...hat.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>, "Naveen
 Krishna Chatradhi" <naveenkrishna.chatradhi@....com>, Suma Hegde
	<suma.hegde@....com>
CC: <linux-kernel@...r.kernel.org>, <linux-edac@...r.kernel.org>,
	<linux-pci@...r.kernel.org>, <linux-hwmon@...r.kernel.org>,
	<platform-driver-x86@...r.kernel.org>
Subject: [PATCH v2 12/16] x86/amd_node: Remove dependency on AMD_NB

Cache the root devices locally so that there are no more dependencies on
AMD_NB.

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

Notes:
    Link:
    https://lore.kernel.org/20241023172150.659002-13-yazen.ghannam@amd.com
    
    v1->v2:
    * Apply to amd_node.c.
    * Change sizeof() parameter in kcalloc().

 arch/x86/kernel/amd_node.c | 42 +++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c
index 0cca541e18d5..45077e2e6f2f 100644
--- a/arch/x86/kernel/amd_node.c
+++ b/arch/x86/kernel/amd_node.c
@@ -8,7 +8,6 @@
  * Author: Yazen Ghannam <Yazen.Ghannam@....com>
  */
 
-#include <asm/amd_nb.h>
 #include <asm/amd_node.h>
 
 /*
@@ -90,6 +89,8 @@ struct pci_dev *amd_node_get_root(u16 node)
 	return root;
 }
 
+static struct pci_dev **amd_roots;
+
 /* Protect the PCI config register pairs used for SMN. */
 static DEFINE_MUTEX(smn_mutex);
 
@@ -135,10 +136,10 @@ static int __amd_smn_rw(u16 node, u32 address, u32 *value, bool write)
 	struct pci_dev *root;
 	int err = -ENODEV;
 
-	if (node >= amd_nb_num())
+	if (node >= amd_num_nodes())
 		return err;
 
-	root = node_to_amd_nb(node)->root;
+	root = amd_roots[node];
 	if (!root)
 		return err;
 
@@ -174,3 +175,38 @@ int __must_check amd_smn_write(u16 node, u32 address, u32 value)
 	return __amd_smn_rw(node, address, &value, true);
 }
 EXPORT_SYMBOL_GPL(amd_smn_write);
+
+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 __init amd_smn_init(void)
+{
+	int err;
+
+	if (!cpu_feature_enabled(X86_FEATURE_ZEN))
+		return 0;
+
+	guard(mutex)(&smn_mutex);
+
+	if (amd_roots)
+		return 0;
+
+	err = amd_cache_roots();
+	if (err)
+		return err;
+
+	return 0;
+}
+
+fs_initcall(amd_smn_init);
-- 
2.43.0