Patch "arm64: efi: Use SMBIOS processor version to key off Ampere quirk" has been added to the 6.2-stable tree

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

    arm64: efi: Use SMBIOS processor version to key off Ampere quirk

to the 6.2-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:
     arm64-efi-use-smbios-processor-version-to-key-off-am.patch
and it can be found in the queue-6.2 subdirectory.

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



commit e54605c4cfdef990e26a4d2de02610ba01b2f7fc
Author: Ard Biesheuvel <ardb@xxxxxxxxxx>
Date:   Tue Feb 28 17:00:49 2023 +0100

    arm64: efi: Use SMBIOS processor version to key off Ampere quirk
    
    [ Upstream commit eb684408f3ea4856639675d6465f0024e498e4b1 ]
    
    Instead of using the SMBIOS type 1 record 'family' field, which is often
    modified by OEMs, use the type 4 'processor ID' and 'processor version'
    fields, which are set to a small set of probe-able values on all known
    Ampere EFI systems in the field.
    
    Fixes: 550b33cfd4452968 ("arm64: efi: Force the use of ...")
    Tested-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
    Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/firmware/efi/libstub/arm64.c b/drivers/firmware/efi/libstub/arm64.c
index 4501652e11ab6..84d94443c601d 100644
--- a/drivers/firmware/efi/libstub/arm64.c
+++ b/drivers/firmware/efi/libstub/arm64.c
@@ -16,20 +16,43 @@
 
 static bool system_needs_vamap(void)
 {
-	const u8 *type1_family = efi_get_smbios_string(1, family);
+	const struct efi_smbios_type4_record *record;
+	const u32 __aligned(1) *socid;
+	const u8 *version;
 
 	/*
 	 * Ampere eMAG, Altra, and Altra Max machines crash in SetTime() if
-	 * SetVirtualAddressMap() has not been called prior.
+	 * SetVirtualAddressMap() has not been called prior. Most Altra systems
+	 * can be identified by the SMCCC soc ID, which is conveniently exposed
+	 * via the type 4 SMBIOS records. Otherwise, test the processor version
+	 * field. eMAG systems all appear to have the processor version field
+	 * set to "eMAG".
 	 */
-	if (!type1_family || (
-	    strcmp(type1_family, "eMAG") &&
-	    strcmp(type1_family, "Altra") &&
-	    strcmp(type1_family, "Altra Max")))
+	record = (struct efi_smbios_type4_record *)efi_get_smbios_record(4);
+	if (!record)
 		return false;
 
-	efi_warn("Working around broken SetVirtualAddressMap()\n");
-	return true;
+	socid = (u32 *)record->processor_id;
+	switch (*socid & 0xffff000f) {
+		static char const altra[] = "Ampere(TM) Altra(TM) Processor";
+		static char const emag[] = "eMAG";
+
+	default:
+		version = efi_get_smbios_string(&record->header, 4,
+						processor_version);
+		if (!version || (strncmp(version, altra, sizeof(altra) - 1) &&
+				 strncmp(version, emag, sizeof(emag) - 1)))
+			break;
+
+		fallthrough;
+
+	case 0x0a160001:	// Altra
+	case 0x0a160002:	// Altra Max
+		efi_warn("Working around broken SetVirtualAddressMap()\n");
+		return true;
+	}
+
+	return false;
 }
 
 efi_status_t check_platform_features(void)
diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index 5b8f2c411ed82..f527816abab3e 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -1054,6 +1054,8 @@ struct efi_smbios_record {
 	u16	handle;
 };
 
+const struct efi_smbios_record *efi_get_smbios_record(u8 type);
+
 struct efi_smbios_type1_record {
 	struct efi_smbios_record	header;
 
@@ -1067,13 +1069,46 @@ struct efi_smbios_type1_record {
 	u8				family;
 };
 
-#define efi_get_smbios_string(__type, __name) ({			\
+struct efi_smbios_type4_record {
+	struct efi_smbios_record	header;
+
+	u8				socket;
+	u8				processor_type;
+	u8				processor_family;
+	u8				processor_manufacturer;
+	u8				processor_id[8];
+	u8				processor_version;
+	u8				voltage;
+	u16				external_clock;
+	u16				max_speed;
+	u16				current_speed;
+	u8				status;
+	u8				processor_upgrade;
+	u16				l1_cache_handle;
+	u16				l2_cache_handle;
+	u16				l3_cache_handle;
+	u8				serial_number;
+	u8				asset_tag;
+	u8				part_number;
+	u8				core_count;
+	u8				enabled_core_count;
+	u8				thread_count;
+	u16				processor_characteristics;
+	u16				processor_family2;
+	u16				core_count2;
+	u16				enabled_core_count2;
+	u16				thread_count2;
+	u16				thread_enabled;
+};
+
+#define efi_get_smbios_string(__record, __type, __name) ({		\
 	int size = sizeof(struct efi_smbios_type ## __type ## _record);	\
 	int off = offsetof(struct efi_smbios_type ## __type ## _record,	\
 			   __name);					\
-	__efi_get_smbios_string(__type, off, size);			\
+	__efi_get_smbios_string((__record), __type, off, size);		\
 })
 
-const u8 *__efi_get_smbios_string(u8 type, int offset, int recsize);
+const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record,
+				  u8 type, int offset, int recsize);
 
 #endif
diff --git a/drivers/firmware/efi/libstub/smbios.c b/drivers/firmware/efi/libstub/smbios.c
index aadb422b9637d..f9c159c28f461 100644
--- a/drivers/firmware/efi/libstub/smbios.c
+++ b/drivers/firmware/efi/libstub/smbios.c
@@ -22,19 +22,28 @@ struct efi_smbios_protocol {
 	u8 minor_version;
 };
 
-const u8 *__efi_get_smbios_string(u8 type, int offset, int recsize)
+const struct efi_smbios_record *efi_get_smbios_record(u8 type)
 {
 	struct efi_smbios_record *record;
 	efi_smbios_protocol_t *smbios;
 	efi_status_t status;
 	u16 handle = 0xfffe;
-	const u8 *strtable;
 
 	status = efi_bs_call(locate_protocol, &EFI_SMBIOS_PROTOCOL_GUID, NULL,
 			     (void **)&smbios) ?:
 		 efi_call_proto(smbios, get_next, &handle, &type, &record, NULL);
 	if (status != EFI_SUCCESS)
 		return NULL;
+	return record;
+}
+
+const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record,
+				  u8 type, int offset, int recsize)
+{
+	const u8 *strtable;
+
+	if (!record)
+		return NULL;
 
 	strtable = (u8 *)record + record->length;
 	for (int i = 1; i < ((u8 *)record)[offset]; i++) {



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