[tip:ras/core] x86/mce: Carve out the crashing_cpu check

tip-bot for Borislav Petkov
2018-06-22T12:41:23Z

Commit-ID: d3d6923cd1ae61a493a405f2f001293ab62eb092
Gitweb: https://git.kernel.org/tip/d3d6923cd1ae61a493a405f2f001293ab62eb092
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Fri, 22 Jun 2018 11:54:24 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 22 Jun 2018 14:37:22 +0200

x86/mce: Carve out the crashing_cpu check

Carve out the rendezvous handler timeout avoidance check into a separate
function in order to simplify the #MC handler.

No functional changes.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20180622095428.626-4-bp@alien8.de

---
arch/x86/kernel/cpu/mcheck/mce.c | 64 +++++++++++++++++++++++-----------------
1 file changed, 37 insertions(+), 27 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index d62201e40027..18804834dbc0 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1104,6 +1104,34 @@ static void mce_unmap_kpfn(unsigned long pfn)
}
#endif

+
+/*
+ * Cases where we avoid rendezvous handler timeout:
+ * 1) If this CPU is offline.
+ *
+ * 2) If crashing_cpu was set, e.g. we're entering kdump and we need to
+ * skip those CPUs which remain looping in the 1st kernel - see
+ * crash_nmi_callback().
+ *
+ * Note: there still is a small window between kexec-ing and the new,
+ * kdump kernel establishing a new #MC handler where a broadcasted MCE
+ * might not get handled properly.
+ */
+static bool __mc_check_crashing_cpu(int cpu)
+{
+ if (cpu_is_offline(cpu) ||
+ (crashing_cpu != -1 && crashing_cpu != cpu)) {
+ u64 mcgstatus;
+
+ mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
+ if (mcgstatus & MCG_STATUS_RIPV) {
+ mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
+ return true;
+ }
+ }
+ return false;
+}
+
/*
* The actual machine check handler. This only handles real
* exceptions when something got corrupted coming in through int 18.
@@ -1118,60 +1146,42 @@ static void mce_unmap_kpfn(unsigned long pfn)
*/
void do_machine_check(struct pt_regs *regs, long error_code)
{
+ DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
+ DECLARE_BITMAP(toclear, MAX_NR_BANKS);
struct mca_config *cfg = &mca_cfg;
+ int cpu = smp_processor_id();
+ char *msg = "Unknown";
struct mce m, *final;
- int i;
int worst = 0;
int severity;
+ int i;

/*
* Establish sequential order between the CPUs entering the machine
* check handler.
*/
int order = -1;
+
/*
* If no_way_out gets set, there is no safe way to recover from this
* MCE. If mca_cfg.tolerant is cranked up, we'll try anyway.
*/
int no_way_out = 0;
+
/*
* If kill_it gets set, there might be a way to recover from this
* error.
*/
int kill_it = 0;
- DECLARE_BITMAP(toclear, MAX_NR_BANKS);
- DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
- char *msg = "Unknown";

/*
* MCEs are always local on AMD. Same is determined by MCG_STATUS_LMCES
* on Intel.
*/
int lmce = 1;
- int cpu = smp_processor_id();
-
- /*
- * Cases where we avoid rendezvous handler timeout:
- * 1) If this CPU is offline.
- *
- * 2) If crashing_cpu was set, e.g. we're entering kdump and we need to
- * skip those CPUs which remain looping in the 1st kernel - see
- * crash_nmi_callback().
- *
- * Note: there still is a small window between kexec-ing and the new,
- * kdump kernel establishing a new #MC handler where a broadcasted MCE
- * might not get handled properly.
- */
- if (cpu_is_offline(cpu) ||
- (crashing_cpu != -1 && crashing_cpu != cpu)) {
- u64 mcgstatus;

- mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
- if (mcgstatus & MCG_STATUS_RIPV) {
- mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
- return;
- }
- }
+ if (__mc_check_crashing_cpu(cpu))
+ return;

ist_enter(regs);