[PATCH v2 01/16] x86/mce: Define mce_setup() helpers for common and per-CPU fields

[Yazen Ghannam]

Generally, MCA information for an error is gathered on the CPU that
reported the error. In this case, CPU-specific information from the
running CPU will be correct.

However, this will be incorrect if the MCA information is gathered while
running on a CPU that didn't report the error. One example is creating
an MCA record using mce_setup() for errors reported from ACPI.

Split mce_setup() so that there is a helper function to gather common,
i.e. not CPU-specific, information and another helper for CPU-specific
information.

Leave mce_setup() defined as-is for the common case when running on the
reporting CPU.

Get MCG_CAP in the global helper even though the register is per-CPU.
This value is not already cached per-CPU like other values. And it does
not assist with any per-CPU decoding or handling.

Signed-off-by: Yazen Ghannam <yazen.ghannam@xxxxxxx>
---

Notes:
    Link:
    https://lkml.kernel.org/r/20231118193248.1296798-3-yazen.ghannam@xxxxxxx
    
    v1->v2:
    * Change helper names and pass-in CPU number (Boris)

 arch/x86/kernel/cpu/mce/core.c     | 34 ++++++++++++++++++++----------
 arch/x86/kernel/cpu/mce/internal.h |  2 ++
 2 files changed, 25 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index b5cc557cfc37..7a857b33f515 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -117,20 +117,32 @@ static struct irq_work mce_irq_work;
  */
 BLOCKING_NOTIFIER_HEAD(x86_mce_decoder_chain);
 
-/* Do initial initialization of a struct mce */
-void mce_setup(struct mce *m)
+void mce_setup_common(struct mce *m)
 {
 	memset(m, 0, sizeof(struct mce));
-	m->cpu = m->extcpu = smp_processor_id();
+
+	m->cpuid	= cpuid_eax(1);
+	m->cpuvendor	= boot_cpu_data.x86_vendor;
+	m->mcgcap	= __rdmsr(MSR_IA32_MCG_CAP);
 	/* need the internal __ version to avoid deadlocks */
-	m->time = __ktime_get_real_seconds();
-	m->cpuvendor = boot_cpu_data.x86_vendor;
-	m->cpuid = cpuid_eax(1);
-	m->socketid = cpu_data(m->extcpu).topo.pkg_id;
-	m->apicid = cpu_data(m->extcpu).topo.initial_apicid;
-	m->mcgcap = __rdmsr(MSR_IA32_MCG_CAP);
-	m->ppin = cpu_data(m->extcpu).ppin;
-	m->microcode = boot_cpu_data.microcode;
+	m->time		= __ktime_get_real_seconds();
+}
+
+void mce_setup_for_cpu(unsigned int cpu, struct mce *m)
+{
+	m->cpu			= cpu;
+	m->extcpu		= cpu;
+	m->apicid		= cpu_data(m->extcpu).topo.initial_apicid;
+	m->microcode		= cpu_data(m->extcpu).microcode;
+	m->ppin			= cpu_data(m->extcpu).ppin;
+	m->socketid		= cpu_data(m->extcpu).topo.pkg_id;
+}
+
+/* Do initial initialization of a struct mce */
+void mce_setup(struct mce *m)
+{
+	mce_setup_common(m);
+	mce_setup_for_cpu(smp_processor_id(), m);
 }
 
 DEFINE_PER_CPU(struct mce, injectm);
diff --git a/arch/x86/kernel/cpu/mce/internal.h b/arch/x86/kernel/cpu/mce/internal.h
index 01f8f03969e6..e86e53695828 100644
--- a/arch/x86/kernel/cpu/mce/internal.h
+++ b/arch/x86/kernel/cpu/mce/internal.h
@@ -261,6 +261,8 @@ enum mca_msr {
 
 /* Decide whether to add MCE record to MCE event pool or filter it out. */
 extern bool filter_mce(struct mce *m);
+void mce_setup_common(struct mce *m);
+void mce_setup_for_cpu(unsigned int cpu, struct mce *m);
 
 #ifdef CONFIG_X86_MCE_AMD
 extern bool amd_filter_mce(struct mce *m);
-- 
2.34.1