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x86/mce: Carve out the crashing_cpu check

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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
This commit is contained in:
Borislav Petkov 2018-06-22 11:54:24 +02:00 committed by Thomas Gleixner
parent bc39f01020
commit d3d6923cd1
1 changed files with 37 additions and 27 deletions
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64
arch/x86/kernel/cpu/mcheck/mce.c
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@ -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);