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powerpc/mce: Avoid nmi_enter/exit in real mode on pseries hash 

Use of nmi_enter/exit in real mode handler causes the kernel to panic
and reboot on injecting SLB mutihit on pseries machine running in hash
MMU mode, because these calls try to accesses memory outside RMO
region in real mode handler where translation is disabled.

Add check to not to use these calls on pseries machine running in hash
MMU mode.

Fixes: 116ac378bb ("powerpc/64s: machine check interrupt update NMI accounting")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201009064005.19777-2-ganeshgr@linux.ibm.com
This commit is contained in:
Ganesh Goudar 2020-10-09 12:10:04 +05:30 committed by Michael Ellerman
parent d4263b12a1
commit 8d0e210127
1 changed files with 3 additions and 4 deletions
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7
arch/powerpc/kernel/mce.c
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@ -591,12 +591,11 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
long notrace machine_check_early(struct pt_regs *regs)
{
long handled = 0;
bool nested = in_nmi();
u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
this_cpu_set_ftrace_enabled(0);
if (!nested)
/* Do not use nmi_enter/exit for pseries hpte guest */
if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
nmi_enter();
hv_nmi_check_nonrecoverable(regs);
@ -607,7 +606,7 @@ long notrace machine_check_early(struct pt_regs *regs)
if (ppc_md.machine_check_early)
handled = ppc_md.machine_check_early(regs);
if (!nested)
if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
nmi_exit();
this_cpu_set_ftrace_enabled(ftrace_enabled);