x86/fpu: Handle FPU-related and clearcpuid command line arguments earlier

FPU initialization handles them currently. However, in the case
of clearcpuid=, some other early initialization code may check for
features before the FPU initialization code is called. Handling the
argument earlier allows the command line to influence those early
initializations.

Signed-off-by: Mike Hommey <mh@glandium.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200921215638.37980-1-mh@glandium.org

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c5d6f17d9b9d38d213524cd2842ee737c94881a7..3c7519398ad5ca88f821c84712bb4502bfc74294 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/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);

diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index f8ff895aaf7e17b8559a3c793453cf06b64d12b1..701f196d7c686621d6d775ce5facd3f6e59f789b 100644 (file)
--- a/arch/x86/kernel/fpu/init.c
+++ b/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>
@@ -237,66 +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[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");
-}
-
 /*
  * 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);
 
        /*