Merge tag 'x86_fpu_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fpu updates from Borislav Petkov:

 - Allow clearcpuid= to accept multiple bits (Arvind Sankar)

 - Move clearcpuid= parameter handling earlier in the boot, away from
   the FPU init code and to a generic location (Mike Hommey)

* tag 'x86_fpu_for_v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/fpu: Handle FPU-related and clearcpuid command line arguments earlier
  x86/fpu: Allow multiple bits in clearcpuid= parameter

Author: torvalds

Documentation/admin-guide/kernel-parameters.txt

@@ -577,7 +577,7 @@
 			loops can be debugged more effectively on production
 			systems.
 
-	clearcpuid=BITNUM [X86]
+	clearcpuid=BITNUM[,BITNUM...] [X86]
 			Disable CPUID feature X for the kernel. See
 			arch/x86/include/asm/cpufeatures.h for the valid bit
 			numbers. Note the Linux specific bits are not necessarily

arch/x86/kernel/cpu/common.c

@@ -23,6 +23,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/pgtable.h>
 
+#include <asm/cmdline.h>
 #include <asm/stackprotector.h>
 #include <asm/perf_event.h>
 #include <asm/mmu_context.h>
@@ -1220,6 +1221,59 @@ static void detect_nopl(void)
 #endif
 }
 
+/*
+ * We parse cpu parameters early because fpu__init_system() is executed
+ * before parse_early_param().
+ */
+static void __init cpu_parse_early_param(void)
+{
+	char arg[128];
+	char *argptr = arg;
+	int arglen, res, bit;
+
+#ifdef CONFIG_X86_32
+	if (cmdline_find_option_bool(boot_command_line, "no387"))
+#ifdef CONFIG_MATH_EMULATION
+		setup_clear_cpu_cap(X86_FEATURE_FPU);
+#else
+		pr_err("Option 'no387' required CONFIG_MATH_EMULATION enabled.\n");
+#endif
+
+	if (cmdline_find_option_bool(boot_command_line, "nofxsr"))
+		setup_clear_cpu_cap(X86_FEATURE_FXSR);
+#endif
+
+	if (cmdline_find_option_bool(boot_command_line, "noxsave"))
+		setup_clear_cpu_cap(X86_FEATURE_XSAVE);
+
+	if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
+		setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
+
+	if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
+		setup_clear_cpu_cap(X86_FEATURE_XSAVES);
+
+	arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));
+	if (arglen <= 0)
+		return;
+
+	pr_info("Clearing CPUID bits:");
+	do {
+		res = get_option(&argptr, &bit);
+		if (res == 0 || res == 3)
+			break;
+
+		/* If the argument was too long, the last bit may be cut off */
+		if (res == 1 && arglen >= sizeof(arg))
+			break;
+
+		if (bit >= 0 && bit < NCAPINTS * 32) {
+			pr_cont(" " X86_CAP_FMT, x86_cap_flag(bit));
+			setup_clear_cpu_cap(bit);
+		}
+	} while (res == 2);
+	pr_cont("\n");
+}
+
 /*
  * Do minimum CPU detection early.
  * Fields really needed: vendor, cpuid_level, family, model, mask,
@@ -1255,6 +1309,7 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 		get_cpu_cap(c);
 		get_cpu_address_sizes(c);
 		setup_force_cpu_cap(X86_FEATURE_CPUID);
+		cpu_parse_early_param();
 
 		if (this_cpu->c_early_init)
 			this_cpu->c_early_init(c);

arch/x86/kernel/fpu/init.c

@@ -5,7 +5,6 @@
 #include <asm/fpu/internal.h>
 #include <asm/tlbflush.h>
 #include <asm/setup.h>
-#include <asm/cmdline.h>
 
 #include <linux/sched.h>
 #include <linux/sched/task.h>
@@ -237,52 +236,12 @@ static void __init fpu__init_system_ctx_switch(void)
 	on_boot_cpu = 0;
 }
 
-/*
- * We parse fpu parameters early because fpu__init_system() is executed
- * before parse_early_param().
- */
-static void __init fpu__init_parse_early_param(void)
-{
-	char arg[32];
-	char *argptr = arg;
-	int bit;
-
-#ifdef CONFIG_X86_32
-	if (cmdline_find_option_bool(boot_command_line, "no387"))
-#ifdef CONFIG_MATH_EMULATION
-		setup_clear_cpu_cap(X86_FEATURE_FPU);
-#else
-		pr_err("Option 'no387' required CONFIG_MATH_EMULATION enabled.\n");
-#endif
-
-	if (cmdline_find_option_bool(boot_command_line, "nofxsr"))
-		setup_clear_cpu_cap(X86_FEATURE_FXSR);
-#endif
-
-	if (cmdline_find_option_bool(boot_command_line, "noxsave"))
-		setup_clear_cpu_cap(X86_FEATURE_XSAVE);
-
-	if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
-		setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
-
-	if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
-		setup_clear_cpu_cap(X86_FEATURE_XSAVES);
-
-	if (cmdline_find_option(boot_command_line, "clearcpuid", arg,
-				sizeof(arg)) &&
-	    get_option(&argptr, &bit) &&
-	    bit >= 0 &&
-	    bit < NCAPINTS * 32)
-		setup_clear_cpu_cap(bit);
-}
-
 /*
  * Called on the boot CPU once per system bootup, to set up the initial
  * FPU state that is later cloned into all processes:
  */
 void __init fpu__init_system(struct cpuinfo_x86 *c)
 {
-	fpu__init_parse_early_param();
 	fpu__init_system_early_generic(c);
 
 	/*