AOSCOS: arm64: Disable MPAM by default

We have to work OotB on W510, and ARM64 does not support extending the
built-in command line with the one from the bootloader.  So only try
MPAM if the user explicitly gives "aosc.try_mpam=1" via the cmdline.

Signed-off-by: Xi Ruoyao <[email protected]>

Author: xry111

arch/arm64/kernel/pi/idreg-override.c

@@ -215,6 +215,17 @@ static const struct ftr_set_desc sw_features __prel64_initconst = {
 	},
 };
 
+static struct arm64_ftr_override __read_mostly aosc_feature_override;
+
+static const struct ftr_set_desc aosc_features __prel64_initconst = {
+	.name		= "aosc",
+	.override	= &aosc_feature_override,
+	.fields		= {
+		FIELD("try_mpam", 0, NULL),
+		{}
+	},
+};
+
 static const
 PREL64(const struct ftr_set_desc, reg) regs[] __prel64_initconst = {
 	{ &mmfr0	},
@@ -226,6 +237,7 @@ PREL64(const struct ftr_set_desc, reg) regs[] __prel64_initconst = {
 	{ &isar2	},
 	{ &smfr0	},
 	{ &sw_features	},
+	{ &aosc_features	},
 };
 
 static const struct {
@@ -390,6 +402,14 @@ static __init void parse_cmdline(const void *fdt, int chosen)
 
 	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && prop)
 		__parse_cmdline(prop, true);
+
+	/*
+	 * Sorry but we have to work OotB on some platforms with broken
+	 * firmware, notably W510.  Use "aosc.try_mpam=1" if you really need
+	 * MPAM on AOSC.
+	 */
+	if (!arm64_apply_feature_override(0, 0, 4, &aosc_feature_override))
+		__parse_cmdline("arm64.nompam", true);
 }
 
 void __init init_feature_override(u64 boot_status, const void *fdt,