FPU initialization handles the clearcpuid command line argument. If it
comes after BSP init, clearcpuid cannot be used to disable features that
trigger some parts of the BSP init code.
Signed-off-by: Mike Hommey <[email protected]>
---
arch/x86/kernel/cpu/common.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
I was trying to use clearcpuid=440 to disable X86_FEATURES_AMD_SSBD to
reproduce the behavior that happens on Zen/Zen+ on a Zen2 machine, but
that didn't work because the command line is handled after the setup for
X86_FEATURE_LS_CFG_SSBD.
I tought about either moving the command line handling earlier, but it
seems there wasn't a specific reason for BSP init being earlier than FPU
initialization so I went with reordering those instead.
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c5d6f17d9b9d..c3bbca91a14b 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1261,9 +1261,6 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
c->cpu_index = 0;
filter_cpuid_features(c, false);
-
- if (this_cpu->c_bsp_init)
- this_cpu->c_bsp_init(c);
} else {
setup_clear_cpu_cap(X86_FEATURE_CPUID);
}
@@ -1276,6 +1273,10 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
fpu__init_system(c);
+ if (have_cpuid_p()) {
+ if (this_cpu->c_bsp_init)
+ this_cpu->c_bsp_init(c);
+ }
#ifdef CONFIG_X86_32
/*
* Regardless of whether PCID is enumerated, the SDM says
--
2.28.0
On Sun, Sep 20, 2020 at 10:03:10AM +0900, Mike Hommey wrote:
> FPU initialization handles the clearcpuid command line argument. If it
> comes after BSP init, clearcpuid cannot be used to disable features that
> trigger some parts of the BSP init code.
>
> Signed-off-by: Mike Hommey <[email protected]>
> ---
> arch/x86/kernel/cpu/common.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> I was trying to use clearcpuid=440 to disable X86_FEATURES_AMD_SSBD to
> reproduce the behavior that happens on Zen/Zen+ on a Zen2 machine, but
> that didn't work because the command line is handled after the setup for
> X86_FEATURE_LS_CFG_SSBD.
>
> I tought about either moving the command line handling earlier, but it
> seems there wasn't a specific reason for BSP init being earlier than FPU
> initialization so I went with reordering those instead.
Our boot order is fragile and the functionality in
fpu__init_parse_early_param() which does the clearcpuid= parsing should be
independent from FPU, as your use case shows.
So I'd prefer if you moved that function perhaps to right after the call
setup_force_cpu_cap(X86_FEATURE_CPUID);
in early_identify_cpu() and renamed it to something generic instead.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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 <[email protected]>
---
arch/x86/kernel/cpu/common.c | 41 ++++++++++++++++++++++++++++++++++++
arch/x86/kernel/fpu/init.c | 41 ------------------------------------
2 files changed, 41 insertions(+), 41 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c5d6f17d9b9d..5e2e4d3621bd 100644
--- 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 +1221,45 @@ static void detect_nopl(void)
#endif
}
+/*
+ * We parse cpu parameters early because early_identify_cpu() is executed
+ * before parse_early_param().
+ */
+static void __init cpu__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);
+}
+
/*
* Do minimum CPU detection early.
* Fields really needed: vendor, cpuid_level, family, model, mask,
@@ -1255,6 +1295,7 @@ 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__init_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 61ddc3a5e5c2..701f196d7c68 100644
--- 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>
@@ -237,52 +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);
/*
--
2.28.0
On Mon, Sep 21, 2020 at 07:00:36AM +0900, Mike Hommey wrote:
> 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 <[email protected]>
> ---
> arch/x86/kernel/cpu/common.c | 41 ++++++++++++++++++++++++++++++++++++
> arch/x86/kernel/fpu/init.c | 41 ------------------------------------
> 2 files changed, 41 insertions(+), 41 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index c5d6f17d9b9d..5e2e4d3621bd 100644
> --- 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 +1221,45 @@ static void detect_nopl(void)
> #endif
> }
>
> +/*
> + * We parse cpu parameters early because early_identify_cpu() is executed
> + * before parse_early_param().
> + */
> +static void __init cpu__init_parse_early_param(void)
Yeah, let's call it simply "cpu_parse_early_param".
Also, I forgot to says this, sorry about that, but can you pls do your
patch ontop of tip/master:
https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/log/
because there are other changes in that area and your patch as is,
doesn't apply.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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 <[email protected]>
---
arch/x86/kernel/cpu/common.c | 55 ++++++++++++++++++++++++++++++++++++
arch/x86/kernel/fpu/init.c | 55 ------------------------------------
2 files changed, 55 insertions(+), 55 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 8d4715e84268..6220fae87263 100644
--- 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 f8ff895aaf7e..701f196d7c68 100644
--- 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);
/*
--
2.28.0
The following commit has been merged into the x86/fpu branch of tip:
Commit-ID: 1ef5423a55c2ac6f1361811efe75b6e46d1023ed
Gitweb: https://git.kernel.org/tip/1ef5423a55c2ac6f1361811efe75b6e46d1023ed
Author: Mike Hommey <[email protected]>
AuthorDate: Tue, 22 Sep 2020 06:56:38 +09:00
Committer: Borislav Petkov <[email protected]>
CommitterDate: Tue, 22 Sep 2020 00:24:27 +02:00
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 <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
---
arch/x86/kernel/cpu/common.c | 55 +++++++++++++++++++++++++++++++++++-
arch/x86/kernel/fpu/init.c | 55 +-----------------------------------
2 files changed, 55 insertions(+), 55 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index c5d6f17..3c75193 100644
--- 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>
@@ -1221,6 +1222,59 @@ static void detect_nopl(void)
}
/*
+ * 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,
* cache alignment.
@@ -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 f8ff895..701f196 100644
--- 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>
@@ -238,65 +237,11 @@ static void __init fpu__init_system_ctx_switch(void)
}
/*
- * 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);
/*