Hi Boris
This is a followup after earlier post [1]
First 2 patches have been merged, sending the rest of the patches after
addressing comments and adding Thomas's reviewed by.
Please review and consider applying.
Changes since last post.
v2:
- Updated commit logs as suggested by Thomas and Boris
- Added Reviewed-by Thomas, and Tony
[1]https://lore.kernel.org/lkml/[email protected]/
Cheers,
Ashok
Ashok Raj (6):
x86/microcode/core: Move microcode_check() to cpu/microcode/core.c
x86/microcode/core: Take a snapshot before and after applying
microcode
x86/microcode: Display revisions only when update is successful
x86/microcode/intel: Use a plain revision argument for
print_ucode_rev()
x86/microcode/intel: Print old and new rev during early boot
x86/microcode/intel: Print when early microcode loading fails
arch/x86/include/asm/processor.h | 3 +-
arch/x86/kernel/cpu/cpu.h | 1 -
arch/x86/kernel/cpu/common.c | 32 --------------
arch/x86/kernel/cpu/microcode/core.c | 62 +++++++++++++++++++++++++--
arch/x86/kernel/cpu/microcode/intel.c | 52 +++++++++++-----------
5 files changed, 83 insertions(+), 67 deletions(-)
base-commit: 1b929c02afd37871d5afb9d498426f83432e71c2
--
2.34.1
microcode_check() is only called from microcode/core.c. Move it and make
it static to prepare for upcoming fix for false negative when checking CPU
features after a microcode update. Also move get_cpu_cap() to processor.h
for general use outside of arch/x86/kernel/cpu/cpu.h
No functional change.
Suggested-by: Alison Schofield <[email protected]>
Signed-off-by: Ashok Raj <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Cc: LKML <[email protected]>
Cc: x86 <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Alison Schofield <[email protected]>
Cc: Reinette Chatre <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Lendacky <[email protected]>
---
arch/x86/include/asm/processor.h | 3 +--
arch/x86/kernel/cpu/cpu.h | 1 -
arch/x86/kernel/cpu/common.c | 32 ----------------------------
arch/x86/kernel/cpu/microcode/core.c | 31 +++++++++++++++++++++++++++
4 files changed, 32 insertions(+), 35 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4e35c66edeb7..70d01ecc39a4 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -182,8 +182,8 @@ extern const struct seq_operations cpuinfo_op;
#define cache_line_size() (boot_cpu_data.x86_cache_alignment)
+extern void get_cpu_cap(struct cpuinfo_x86 *c);
extern void cpu_detect(struct cpuinfo_x86 *c);
-
static inline unsigned long long l1tf_pfn_limit(void)
{
return BIT_ULL(boot_cpu_data.x86_cache_bits - 1 - PAGE_SHIFT);
@@ -697,7 +697,6 @@ bool xen_set_default_idle(void);
#endif
void __noreturn stop_this_cpu(void *dummy);
-void microcode_check(void);
enum l1tf_mitigations {
L1TF_MITIGATION_OFF,
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 7c9b5893c30a..a142b8d543a3 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -63,7 +63,6 @@ static inline void tsx_ap_init(void) { }
extern void init_spectral_chicken(struct cpuinfo_x86 *c);
-extern void get_cpu_cap(struct cpuinfo_x86 *c);
extern void get_cpu_address_sizes(struct cpuinfo_x86 *c);
extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
extern void init_scattered_cpuid_features(struct cpuinfo_x86 *c);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 9cfca3d7d0e2..7b06034eeddc 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2296,38 +2296,6 @@ void cpu_init_secondary(void)
}
#endif
-#ifdef CONFIG_MICROCODE_LATE_LOADING
-/*
- * The microcode loader calls this upon late microcode load to recheck features,
- * only when microcode has been updated. Caller holds microcode_mutex and CPU
- * hotplug lock.
- */
-void microcode_check(void)
-{
- struct cpuinfo_x86 info;
-
- perf_check_microcode();
-
- /* Reload CPUID max function as it might've changed. */
- info.cpuid_level = cpuid_eax(0);
-
- /*
- * Copy all capability leafs to pick up the synthetic ones so that
- * memcmp() below doesn't fail on that. The ones coming from CPUID will
- * get overwritten in get_cpu_cap().
- */
- memcpy(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability));
-
- get_cpu_cap(&info);
-
- if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability)))
- return;
-
- pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
- pr_warn("x86/CPU: Please consider either early loading through initrd/built-in or a potential BIOS update.\n");
-}
-#endif
-
/*
* Invoked from core CPU hotplug code after hotplug operations
*/
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index c4cd7328177b..0051ebf7c53e 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -432,6 +432,37 @@ static int __reload_late(void *info)
return ret;
}
+/*
+ * The microcode loader calls this upon late microcode load to recheck features,
+ * only when microcode has been updated. Caller holds microcode_mutex and CPU
+ * hotplug lock.
+ */
+static void microcode_check(void)
+{
+ struct cpuinfo_x86 info;
+
+ perf_check_microcode();
+
+ /* Reload CPUID max function as it might've changed. */
+ info.cpuid_level = cpuid_eax(0);
+
+ /*
+ * Copy all capability leafs to pick up the synthetic ones so that
+ * memcmp() below doesn't fail on that. The ones coming from CPUID will
+ * get overwritten in get_cpu_cap().
+ */
+ memcpy(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability));
+
+ get_cpu_cap(&info);
+
+ if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability,
+ sizeof(info.x86_capability)))
+ return;
+
+ pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
+ pr_warn("x86/CPU: Please consider either early loading through initrd/built-in or a potential BIOS update.\n");
+}
+
/*
* Reload microcode late on all CPUs. Wait for a sec until they
* all gather together.
--
2.34.1
Right now, microcode loading failures and successes print the same
message "Reloading completed". This is misleading to users.
Display the updated revision number only if an update was successful.
Suggested-by: Thomas Gleixner <[email protected]>
Signed-off-by: Ashok Raj <[email protected]>
Reviewed-by: Tony Luck <[email protected]>
Link: https://lore.kernel.org/lkml/874judpqqd.ffs@tglx/
Cc: LKML <[email protected]>
Cc: x86 <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Alison Schofield <[email protected]>
Cc: Reinette Chatre <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Lendacky <[email protected]>
---
arch/x86/kernel/cpu/microcode/core.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index e2cdf3e989e7..e60cf0f66bf5 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -500,11 +500,12 @@ static int microcode_reload_late(void)
store_cpu_caps(&info);
ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
- if (ret == 0)
- microcode_check(&info);
- pr_info("Reload completed, microcode revision: 0x%x -> 0x%x\n",
- old, boot_cpu_data.microcode);
+ if (ret == 0) {
+ pr_info("Reload completed, microcode revision: 0x%x -> 0x%x\n",
+ old, boot_cpu_data.microcode);
+ microcode_check(&info);
+ }
return ret;
}
--
2.34.1
The kernel caches features about each CPU's features at boot in an
x86_capability[] structure. The microcode update takes one snapshot and
compares it with the saved copy at boot.
However, the capabilities in the boot copy can be turned off as a result of
certain command line parameters or configuration restrictions. This can
cause a mismatch when comparing the values before and after the microcode
update.
microcode_check() is called after an update to report any previously
cached CPUID bits might have changed due to the update.
store_cpu_caps() basically stores the original CPU reported values and not
the OS modified values. This will avoid giving a false warning even if no
capabilities have changed.
Ignore the capabilities recorded at boot. Take a new snapshot before the
update and compare with a snapshot after the update to eliminate the false
warning.
Fixes: 1008c52c09dc ("x86/CPU: Add a microcode loader callback")
Signed-off-by: Ashok Raj <[email protected]>
Cc: LKML <[email protected]>
Cc: x86 <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Alison Schofield <[email protected]>
Cc: Reinette Chatre <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Lendacky <[email protected]>
---
Changes since last post
- Boris : Change function from copy_cpu_caps() -> store_cpu_caps()
- Thomas : Commit log changes.
---
arch/x86/kernel/cpu/microcode/core.c | 42 +++++++++++++++++++++-------
1 file changed, 32 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 0051ebf7c53e..e2cdf3e989e7 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -432,12 +432,28 @@ static int __reload_late(void *info)
return ret;
}
+static void store_cpu_caps(struct cpuinfo_x86 *info)
+{
+ /* Reload CPUID max function as it might've changed. */
+ info->cpuid_level = cpuid_eax(0);
+
+ /*
+ * Copy all capability leafs to pick up the synthetic ones so that
+ * memcmp() below doesn't fail on that. The ones coming from CPUID will
+ * get overwritten in get_cpu_cap().
+ */
+ memcpy(info->x86_capability, &boot_cpu_data.x86_capability,
+ sizeof(info->x86_capability));
+
+ get_cpu_cap(info);
+}
+
/*
* The microcode loader calls this upon late microcode load to recheck features,
* only when microcode has been updated. Caller holds microcode_mutex and CPU
* hotplug lock.
*/
-static void microcode_check(void)
+static void microcode_check(struct cpuinfo_x86 *orig)
{
struct cpuinfo_x86 info;
@@ -447,15 +463,13 @@ static void microcode_check(void)
info.cpuid_level = cpuid_eax(0);
/*
- * Copy all capability leafs to pick up the synthetic ones so that
- * memcmp() below doesn't fail on that. The ones coming from CPUID will
- * get overwritten in get_cpu_cap().
- */
- memcpy(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability));
+ * Copy all capability leafs to pick up the synthetic ones so that
+ * memcmp() below doesn't fail on that. The ones coming from CPUID will
+ * get overwritten in get_cpu_cap().
+ */
+ store_cpu_caps(&info);
- get_cpu_cap(&info);
-
- if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability,
+ if (!memcmp(&info.x86_capability, &orig->x86_capability,
sizeof(info.x86_capability)))
return;
@@ -470,6 +484,7 @@ static void microcode_check(void)
static int microcode_reload_late(void)
{
int old = boot_cpu_data.microcode, ret;
+ struct cpuinfo_x86 info;
pr_err("Attempting late microcode loading - it is dangerous and taints the kernel.\n");
pr_err("You should switch to early loading, if possible.\n");
@@ -477,9 +492,16 @@ static int microcode_reload_late(void)
atomic_set(&late_cpus_in, 0);
atomic_set(&late_cpus_out, 0);
+ /*
+ * Take a snapshot before the microcode update, so we can compare
+ * them after the update is successful to check for any bits
+ * changed.
+ */
+ store_cpu_caps(&info);
+
ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
if (ret == 0)
- microcode_check();
+ microcode_check(&info);
pr_info("Reload completed, microcode revision: 0x%x -> 0x%x\n",
old, boot_cpu_data.microcode);
--
2.34.1
On Tue, Dec 27, 2022 at 11:23:35AM -0800, Ashok Raj wrote:
> microcode_check() is only called from microcode/core.c. Move it and make
> it static to prepare for upcoming fix for false negative when checking CPU
> features after a microcode update. Also move get_cpu_cap() to processor.h
> for general use outside of arch/x86/kernel/cpu/cpu.h
I thought we agreed not to do this:
https://lore.kernel.org/r/Y44bbZMMf8I6Lzl/@zn.tnic
Or was this a misunderstanding?
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Tue, Dec 27, 2022 at 08:50:25PM +0100, Borislav Petkov wrote:
> On Tue, Dec 27, 2022 at 11:23:35AM -0800, Ashok Raj wrote:
> > microcode_check() is only called from microcode/core.c. Move it and make
> > it static to prepare for upcoming fix for false negative when checking CPU
> > features after a microcode update. Also move get_cpu_cap() to processor.h
> > for general use outside of arch/x86/kernel/cpu/cpu.h
>
> I thought we agreed not to do this:
>
> https://lore.kernel.org/r/Y44bbZMMf8I6Lzl/@zn.tnic
>
> Or was this a misunderstanding?
Bah... you are correct, I should drop this one.
I'll fix it up
Cheers,
Ashok
This is a preparation before the next patch uses this to compare CPU
capabilities after performing an update.
Add a parameter to store CPU capabilities before performing a microcode
update.
Signed-off-by: Ashok Raj <[email protected]>
Cc: LKML <[email protected]>
Cc: x86 <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Alison Schofield <[email protected]>
Cc: Reinette Chatre <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Lendacky <[email protected]>
---
arch/x86/include/asm/processor.h | 2 +-
arch/x86/kernel/cpu/common.c | 12 +++++-------
arch/x86/kernel/cpu/microcode/core.c | 3 ++-
3 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4e35c66edeb7..387578049de0 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -697,7 +697,7 @@ bool xen_set_default_idle(void);
#endif
void __noreturn stop_this_cpu(void *dummy);
-void microcode_check(void);
+void microcode_check(struct cpuinfo_x86 *info);
enum l1tf_mitigations {
L1TF_MITIGATION_OFF,
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 9cfca3d7d0e2..b9c7529c920e 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2302,25 +2302,23 @@ void cpu_init_secondary(void)
* only when microcode has been updated. Caller holds microcode_mutex and CPU
* hotplug lock.
*/
-void microcode_check(void)
+void microcode_check(struct cpuinfo_x86 *info)
{
- struct cpuinfo_x86 info;
-
perf_check_microcode();
/* Reload CPUID max function as it might've changed. */
- info.cpuid_level = cpuid_eax(0);
+ info->cpuid_level = cpuid_eax(0);
/*
* Copy all capability leafs to pick up the synthetic ones so that
* memcmp() below doesn't fail on that. The ones coming from CPUID will
* get overwritten in get_cpu_cap().
*/
- memcpy(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability));
+ memcpy(&info->x86_capability, &boot_cpu_data.x86_capability, sizeof(info->x86_capability));
- get_cpu_cap(&info);
+ get_cpu_cap(info);
- if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability)))
+ if (!memcmp(&info->x86_capability, &boot_cpu_data.x86_capability, sizeof(info->x86_capability)))
return;
pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index c4cd7328177b..d86a4f910a6b 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -439,6 +439,7 @@ static int __reload_late(void *info)
static int microcode_reload_late(void)
{
int old = boot_cpu_data.microcode, ret;
+ struct cpuinfo_x86 info;
pr_err("Attempting late microcode loading - it is dangerous and taints the kernel.\n");
pr_err("You should switch to early loading, if possible.\n");
@@ -448,7 +449,7 @@ static int microcode_reload_late(void)
ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
if (ret == 0)
- microcode_check();
+ microcode_check(&info);
pr_info("Reload completed, microcode revision: 0x%x -> 0x%x\n",
old, boot_cpu_data.microcode);
--
2.34.1
The kernel caches features about each CPU's features at boot in an
x86_capability[] structure. The microcode update takes one snapshot and
compares it with the saved copy at boot.
However, the capabilities in the boot copy can be turned off as a result of
certain command line parameters or configuration restrictions. This can
cause a mismatch when comparing the values before and after the microcode
update.
microcode_check() is called after an update to report any previously
cached CPUID bits might have changed due to the update.
microcode_store_cpu_caps() basically stores the original CPU reported
values and not the OS modified values. This will avoid giving a false
warning even if no capabilities have changed.
Ignore the capabilities recorded at boot. Take a new snapshot before the
update and compare with a snapshot after the update to eliminate the false
warning.
Fixes: 1008c52c09dc ("x86/CPU: Add a microcode loader callback")
Signed-off-by: Ashok Raj <[email protected]>
Cc: LKML <[email protected]>
Cc: x86 <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Alison Schofield <[email protected]>
Cc: Reinette Chatre <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Lendacky <[email protected]>
---
Changes since last post
- Boris
- Change function from copy_cpu_caps() -> store_cpu_caps()
- Keep microcode_check() inside cpu/common.c and not bleed
get_cpu_caps() outside of core code.
- Thomas : Commit log changes.
---
arch/x86/include/asm/processor.h | 1 +
arch/x86/kernel/cpu/common.c | 17 +++++++++++++++++
arch/x86/kernel/cpu/microcode/core.c | 7 +++++++
3 files changed, 25 insertions(+)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 387578049de0..ac2e67156b9b 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -697,6 +697,7 @@ bool xen_set_default_idle(void);
#endif
void __noreturn stop_this_cpu(void *dummy);
+void microcode_store_cpu_caps(struct cpuinfo_x86 *info);
void microcode_check(struct cpuinfo_x86 *info);
enum l1tf_mitigations {
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index b9c7529c920e..1f0b57a5d89d 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2297,6 +2297,23 @@ void cpu_init_secondary(void)
#endif
#ifdef CONFIG_MICROCODE_LATE_LOADING
+
+void microcode_store_cpu_caps(struct cpuinfo_x86 *info)
+{
+ /* Reload CPUID max function as it might've changed. */
+ info->cpuid_level = cpuid_eax(0);
+
+ /*
+ * Copy all capability leafs to pick up the synthetic ones so that
+ * memcmp() below doesn't fail on that. The ones coming from CPUID will
+ * get overwritten in get_cpu_cap().
+ */
+ memcpy(info->x86_capability, &boot_cpu_data.x86_capability,
+ sizeof(info->x86_capability));
+
+ get_cpu_cap(info);
+}
+
/*
* The microcode loader calls this upon late microcode load to recheck features,
* only when microcode has been updated. Caller holds microcode_mutex and CPU
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index d86a4f910a6b..14d9031ed68a 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -447,6 +447,13 @@ static int microcode_reload_late(void)
atomic_set(&late_cpus_in, 0);
atomic_set(&late_cpus_out, 0);
+ /*
+ * Take a snapshot before the microcode update, so we can compare
+ * them after the update is successful to check for any bits
+ * changed.
+ */
+ microcode_store_cpu_caps(&info);
+
ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
if (ret == 0)
microcode_check(&info);
--
2.34.1
On Tue, Dec 27, 2022 at 01:01:44PM -0800, Ashok Raj wrote:
> The kernel caches features about each CPU's features at boot in an
> x86_capability[] structure. The microcode update takes one snapshot and
> compares it with the saved copy at boot.
>
> However, the capabilities in the boot copy can be turned off as a result of
> certain command line parameters or configuration restrictions. This can
> cause a mismatch when comparing the values before and after the microcode
> update.
>
> microcode_check() is called after an update to report any previously
> cached CPUID bits might have changed due to the update.
>
I'll send you a clean version. Somehow this picked up an interim change and
the change to microcode_check() is not there. I remember testing but it
happened to be a different system I updated.
I'll send something after the new years.. working during holidays isn't
efficient :-(.
Cheers,
Ashok