[PATCH 12/16] x86/amd_smn: Remove dependency on AMD_NB

Yazen Ghannam
2024-10-23T17:22:21Z

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

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
arch/x86/kernel/amd_smn.c | 42 ++++++++++++++++++++++++++++++++++++---
1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/amd_smn.c b/arch/x86/kernel/amd_smn.c
index e53db07d1a77..45cf86cd9014 100644
--- a/arch/x86/kernel/amd_smn.c
+++ b/arch/x86/kernel/amd_smn.c
@@ -8,9 +8,10 @@

#include <linux/pci.h>

-#include <asm/amd_nb.h>
#include <asm/amd_smn.h>

+static struct pci_dev **amd_roots;
+
/* Protect the PCI config register pairs used for SMN. */
static DEFINE_MUTEX(smn_mutex);

@@ -56,10 +57,10 @@ 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;

@@ -95,3 +96,38 @@ 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(struct pci_dev *), 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