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Message-Id: <20221103175901.164783-5-ashok.raj@intel.com>
Date: Thu, 3 Nov 2022 17:58:52 +0000
From: Ashok Raj <ashok.raj@...el.com>
To: Borislav Petkov <bp@...en8.de>,
Thomas Gleixner <tglx@...utronix.de>
Cc: "LKML Mailing List" <linux-kernel@...r.kernel.org>,
X86-kernel <x86@...nel.org>, Tony Luck <tony.luck@...el.com>,
Dave Hansen <dave.hansen@...el.com>,
Arjan van de Ven <arjan.van.de.ven@...el.com>,
Andy Lutomirski <luto@...nel.org>,
Jacon Jun Pan <jacob.jun.pan@...el.com>,
Tom Lendacky <thomas.lendacky@....com>,
Kai Huang <kai.huang@...el.com>,
Andrew Cooper <andrew.cooper3@...rix.com>,
Ashok Raj <ashok.raj@...el.com>
Subject: [v2 04/13] x86/microcode: Fix microcode_check() compare after a new uCode update
microcode_check() seems to take a snapshot after an update to compare with
previously cached values of x86_capabilities. Some capabilities can be
turned off by OS as a result of certain command line parameters or due to
some configuration.
Even though there was no change in CPUID bits, reloading the same microcode
threw a warning, that some CPUID bits changed.
To eliminate the false warning, take a snapshot before the update and one
after the update. This eliminates the miscompare.
Also move the microcode_check() from cpu/common.c -> cpu/microcode/core.c
Reviewed-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Ashok Raj <ashok.raj@...el.com>
---
arch/x86/include/asm/processor.h | 1 -
arch/x86/kernel/cpu/common.c | 32 -----------------
arch/x86/kernel/cpu/microcode/core.c | 51 +++++++++++++++++++++++++++-
3 files changed, 50 insertions(+), 34 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 67c9d73b31fa..2acc8ae0bf47 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -835,7 +835,6 @@ 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/common.c b/arch/x86/kernel/cpu/common.c
index 3e508f239098..bbd362ead043 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2305,38 +2305,6 @@ 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 712aafff96e0..9ed1f6e138d6 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -40,6 +40,8 @@
#include <asm/cmdline.h>
#include <asm/setup.h>
+#include "../cpu.h"
+
#define DRIVER_VERSION "2.2"
static struct microcode_ops *microcode_ops;
@@ -431,6 +433,51 @@ static int __reload_late(void *info)
return ret;
}
+static void copy_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(struct cpuinfo_x86 *orig)
+{
+ 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, &orig->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.
@@ -438,6 +485,7 @@ 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");
@@ -445,9 +493,10 @@ static int microcode_reload_late(void)
atomic_set(&late_cpus_in, 0);
atomic_set(&late_cpus_out, 0);
+ copy_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
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