On Wed, Jun 30, 2021 at 06:22:54PM +0200, Borislav Petkov wrote:

On Wed, Jun 23, 2021 at 07:19:35PM +0000, Yazen Ghannam wrote:

quoted

The DF Indirect Access method allows for "Broadcast" accesses in which
case no specific instance is targeted. Add support using a reserved
instance ID of 0xFF to indicate a broadcast access. Set the FICAA
register appropriately.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
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v1->v2:
* New in v2.

 drivers/edac/amd64_edac.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index b94067e3952b..d67cd8f57b94 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c

@@ -1010,7 +1010,11 @@ struct df_reg {
  *
  * Fabric Indirect Configuration Access Data (FICAD): There are FICAD LO
  * and FICAD HI registers but so far we only need the LO register.
+ *
+ * Use Instance Id 0xFF to indicate a broadcast read.
  */
+
+#define DF_BROADCAST	0xFF
 static int amd_df_indirect_read(u16 node, struct df_reg reg, u8 instance_id, u32 *lo)
 {
 	struct pci_dev *F4;

@@ -1024,7 +1028,7 @@ static int amd_df_indirect_read(u16 node, struct df_reg reg, u8 instance_id, u32
 	if (!F4)
 		goto out;
 
-	ficaa  = 1;
+	ficaa  = (instance_id == DF_BROADCAST) ? 0 : 1;

Or, you can define two functions:

df_indirect_read_broadcast()
df_indirect_read_umc()

(no need for the "amd_" prefix either - this is a static function now)

which both call a low-level helper:

static int __df_indirect_read(u16 node, struct df_reg reg, u8 instance_id, u32 *lo)

and there you either pass the instance_id or 0xff depending on which
outer function is calling it...

Yeah, I like it. I'll see what I can do.

BTW, I'm thinking to include a "tmp" or "scratch" u32 value in the
context used to hold raw register values that don't need to be saved
long term. There are a few places where a value is read and some fields
are extracted, so a few functions have a u32 tmp variable declared. What
do you think?

Thanks,
Yazen