@@ -1077,6 +1077,27 @@ void cpu_set_radix_mode(void)
cpu_change_all_hid0(&req);
}
+static void cpu_cleanup_one(void *param __unused)
+{
+ mtspr(SPR_AMR, 0);
+ mtspr(SPR_IAMR, 0);
+}
+
+static int64_t cpu_cleanup_all(void)
+{
+ struct cpu_thread *cpu;
+
+ for_each_available_cpu(cpu) {
+ if (cpu == this_cpu()) {
+ cpu_cleanup_one(NULL);
+ continue;
+ }
+ cpu_wait_job(cpu_queue_job(cpu, "cpu_cleanup",
+ cpu_cleanup_one, NULL), true);
+ }
+ return OPAL_SUCCESS;
+}
+
void cpu_fast_reboot_complete(void)
{
/* Fast reboot will have cleared HID0:HILE */
@@ -1132,6 +1153,14 @@ static int64_t opal_reinit_cpus(uint64_t flags)
this_cpu()->in_reinit = true;
unlock(&reinit_lock);
+ /*
+ * This cleans up a few things left over by Linux
+ * that can cause problems in cases such as radix->hash
+ * transitions. Ideally Linux should do it but doing it
+ * here works around existing broken kernels.
+ */
+ cpu_cleanup_all();
+
/* If HILE change via HID0 is supported ... */
if (hile_supported &&
(flags & (OPAL_REINIT_CPUS_HILE_BE |
@@ -51,6 +51,8 @@
#define SPR_SRR0 0x01a /* RW: Exception save/restore reg 0 */
#define SPR_SRR1 0x01b /* RW: Exception save/restore reg 1 */
#define SPR_CFAR 0x01c /* RW: Come From Address Register */
+#define SPR_AMR 0x01d /* RW: Authority Mask Register */
+#define SPR_IAMR 0x03d /* RW: Instruction Authority Mask Register */
#define SPR_RPR 0x0ba /* RW: Relative Priority Register */
#define SPR_TBRL 0x10c /* RO: Timebase low */
#define SPR_TBRU 0x10d /* RO: Timebase high */
There's a bug in current Linux kernels leaving crap in those registers accross kexec and not sanitizing them on boot. This breaks kexec under some circumstances (such as booting a hash kernel from a radix one on P9 DD2.0). The long term fix is in Linux, but this workaround is a reasonable way of "sanitizing" those SPRs when Linux calls opal_reinit_cpus() and shouldn't have adverse effects. We could also use that same mechanism to cleanup other things as well such as restoring some other SPRs to their default value in the future. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> --- Balbir, can you sort out the kernel ? It should cleanup AMR/IAMR on entry at least, preferably on kexec too. core/cpu.c | 29 +++++++++++++++++++++++++++++ include/processor.h | 2 ++ 2 files changed, 31 insertions(+)