linux-kernel - [PATCH AUTOSEL 6.9 33/44] platform/x86/amd/hsmp: Check HSMP support on AMD family of processors

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Date: Mon, 17 Jun 2024 09:19:46 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Suma Hegde <suma.hegde@....com>,
	Naveen Krishna Chatradhi <naveenkrishna.chatradhi@....com>,
	Hans de Goede <hdegoede@...hat.com>,
	Sasha Levin <sashal@...nel.org>,
	ilpo.jarvinen@...ux.intel.com,
	platform-driver-x86@...r.kernel.org
Subject: [PATCH AUTOSEL 6.9 33/44] platform/x86/amd/hsmp: Check HSMP support on AMD family of processors

From: Suma Hegde <suma.hegde@....com>

[ 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@....com>
Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@....com>
Link: https://lore.kernel.org/r/20240603081512.142909-1-suma.hegde@amd.com
Reviewed-by: Hans de Goede <hdegoede@...hat.com>
Signed-off-by: Hans de Goede <hdegoede@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/platform/x86/amd/hsmp.c | 50 ++++++++++++++++++++++++++++-----
 1 file changed, 43 insertions(+), 7 deletions(-)

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);
 	}
-- 
2.43.0