[PATCH v2 12/16] x86/amd_node: Remove dependency on AMD_NB

Yazen Ghannam
2024-12-06T16:12:41Z

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

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