Patch "platform/x86/amd/hsmp: Check HSMP support on AMD family of processors" has been added to the 6.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    platform/x86/amd/hsmp: Check HSMP support on AMD family of processors

to the 6.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     platform-x86-amd-hsmp-check-hsmp-support-on-amd-fami.patch
and it can be found in the queue-6.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 137d99d8a96545b99cab2bfe589813f0df91a35f
Author: Suma Hegde <suma.hegde@xxxxxxx>
Date:   Mon Jun 3 08:15:12 2024 +0000

    platform/x86/amd/hsmp: Check HSMP support on AMD family of processors
    
    [ Upstream commit 77f1972bdcf7513293e8bbe376b9fe837310ee9c ]
    
    HSMP interface is supported only on few x86 processors from AMD.
    Accessing HSMP registers on rest of the platforms might cause
    unexpected behaviour. So add a check.
    
    Also unavailability of this interface on rest of the processors
    is not an error. Hence, use pr_info() instead of the pr_err() to
    log the message.
    
    Signed-off-by: Suma Hegde <suma.hegde@xxxxxxx>
    Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@xxxxxxx>
    Link: https://lore.kernel.org/r/20240603081512.142909-1-suma.hegde@xxxxxxx
    Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>
    Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/platform/x86/amd/hsmp.c b/drivers/platform/x86/amd/hsmp.c
index 1927be901108e..272d32a95e216 100644
--- a/drivers/platform/x86/amd/hsmp.c
+++ b/drivers/platform/x86/amd/hsmp.c
@@ -907,16 +907,44 @@ static int hsmp_plat_dev_register(void)
 	return ret;
 }
 
+/*
+ * This check is only needed for backward compatibility of previous platforms.
+ * All new platforms are expected to support ACPI based probing.
+ */
+static bool legacy_hsmp_support(void)
+{
+	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
+		return false;
+
+	switch (boot_cpu_data.x86) {
+	case 0x19:
+		switch (boot_cpu_data.x86_model) {
+		case 0x00 ... 0x1F:
+		case 0x30 ... 0x3F:
+		case 0x90 ... 0x9F:
+		case 0xA0 ... 0xAF:
+			return true;
+		default:
+			return false;
+		}
+	case 0x1A:
+		switch (boot_cpu_data.x86_model) {
+		case 0x00 ... 0x1F:
+			return true;
+		default:
+			return false;
+		}
+	default:
+		return false;
+	}
+
+	return false;
+}
+
 static int __init hsmp_plt_init(void)
 {
 	int ret = -ENODEV;
 
-	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD || boot_cpu_data.x86 < 0x19) {
-		pr_err("HSMP is not supported on Family:%x model:%x\n",
-		       boot_cpu_data.x86, boot_cpu_data.x86_model);
-		return ret;
-	}
-
 	/*
 	 * amd_nb_num() returns number of SMN/DF interfaces present in the system
 	 * if we have N SMN/DF interfaces that ideally means N sockets
@@ -930,7 +958,15 @@ static int __init hsmp_plt_init(void)
 		return ret;
 
 	if (!plat_dev.is_acpi_device) {
-		ret = hsmp_plat_dev_register();
+		if (legacy_hsmp_support()) {
+			/* Not ACPI device, but supports HSMP, register a plat_dev */
+			ret = hsmp_plat_dev_register();
+		} else {
+			/* Not ACPI, Does not support HSMP */
+			pr_info("HSMP is not supported on Family:%x model:%x\n",
+				boot_cpu_data.x86, boot_cpu_data.x86_model);
+			ret = -ENODEV;
+		}
 		if (ret)
 			platform_driver_unregister(&amd_hsmp_driver);
 	}