The system reset interrupt may use HSRR registers (e.g., to call in to
OPAL), but code that uses HSRR registers is not required to clear
MSR[RI] by convention.
Rather than introduce that requirement, have system reset interrupt
save HSRRs before they might be used.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/kernel/traps.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index b429b2264a1f..d54459152a2b 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -438,14 +438,32 @@ void hv_nmi_check_nonrecoverable(struct pt_regs *regs)
void system_reset_exception(struct pt_regs *regs)
{
+ unsigned long hsrr0, hsrr1;
+ bool hsrrs_saved = false;
+ bool nested = in_nmi();
+
/*
* Avoid crashes in case of nested NMI exceptions. Recoverability
* is determined by RI and in_nmi
*/
- bool nested = in_nmi();
if (!nested)
nmi_enter();
+ /*
+ * System reset can interrupt a region where HSRRs are live and
+ * MSR[RI]=1, and it may clobber HSRRs itself (e.g., to call OPAL),
+ * so save them before doing anything.
+ *
+ * Machine checks should be okay to avoid this, as the real mode
+ * handler is careful to avoid HSRRs, and the virt code is not
+ * delivered as an NMI.
+ */
+ if (cpu_has_feature(CPU_FTR_HVMODE)) {
+ hsrrs_saved = true;
+ hsrr0 = mfspr(SPRN_HSRR0);
+ hsrr1 = mfspr(SPRN_HSRR1);
+ }
+
hv_nmi_check_nonrecoverable(regs);
__this_cpu_inc(irq_stat.sreset_irqs);
@@ -495,6 +513,11 @@ void system_reset_exception(struct pt_regs *regs)
if (!(regs->msr & MSR_RI))
nmi_panic(regs, "Unrecoverable System Reset");
+ if (hsrrs_saved) {
+ mtspr(SPRN_HSRR0, hsrr0);
+ mtspr(SPRN_HSRR1, hsrr1);
+ }
+
if (!nested)
nmi_exit();
--
2.18.0
