Re: [PATCH v3 1/2] powerpc/mce: remove nmi_enter/exit from real mode handler
From: Ganesh <hidden>
Date: 2020-10-09 06:36:17
On 10/1/20 11:21 PM, Ganesh Goudar wrote:
quoted hunk ↗ jump to hunk
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, As 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") Signed-off-by: Ganesh Goudar <redacted> --- arch/powerpc/kernel/mce.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c index ada59f6c4298..3bf39dd5dd43 100644 --- a/arch/powerpc/kernel/mce.c +++ b/arch/powerpc/kernel/mce.c@@ -591,12 +591,14 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info); long notrace machine_check_early(struct pt_regs *regs) { long handled = 0; - bool nested = in_nmi(); + bool is_pseries_hpt_guest; u8 ftrace_enabled = this_cpu_get_ftrace_enabled(); this_cpu_set_ftrace_enabled(0); - - if (!nested) + is_pseries_hpt_guest = machine_is(pseries) && + mmu_has_feature(MMU_FTR_HPTE_TABLE); + /* Do not use nmi_enter/exit for pseries hpte guest */ + if (!is_pseries_hpt_guest)
In an offline discussion mpe suggested to use radix_enabled() to check if it is radix or hash, as MMU_FTR_HPTE_TABLE may be true on radix machines also and use of FW_FEATURE_LPAR better than machine_is(pseries), sending v4 with these changes.
quoted hunk ↗ jump to hunk
nmi_enter(); hv_nmi_check_nonrecoverable(regs);@@ -607,7 +609,7 @@ 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 (!is_pseries_hpt_guest) nmi_exit(); this_cpu_set_ftrace_enabled(ftrace_enabled);