From: Ganesh Goudar ganeshgr@linux.ibm.com
commit 8d0e2101274358d9b6b1f27232b40253ca48bab5 upstream.
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: 116ac378bb3f ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/powerpc/kernel/mce.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
--- a/arch/powerpc/kernel/mce.c +++ b/arch/powerpc/kernel/mce.c @@ -591,12 +591,11 @@ EXPORT_SYMBOL_GPL(machine_check_print_ev 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 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);