From 18aa0da33e18cb2037932f7ad5c7d51f22e012f5 Mon Sep 17 00:00:00 2001
From: Paul Mackerras <paulus@samba.org>
Date: Fri, 11 Apr 2014 16:43:35 +1000
Subject: [PATCH] powerpc: Don't try to set LPCR unless we're in hypervisor
mode
Commit 8f619b5429d9 ("powerpc/ppc64: Do not turn AIL (reloc-on
interrupts) too early") added code to set the AIL bit in the LPCR
without checking whether the kernel is running in hypervisor mode. The
result is that when the kernel is running as a guest (i.e., under
PowerKVM or PowerVM), the processor takes a privileged instruction
interrupt at that point, causing a panic. The visible result is that
the kernel hangs after printing "returning from prom_init".
This fixes it by checking for hypervisor mode being available before
setting LPCR. If we are not in hypervisor mode, we enable relocation-on
interrupts later in pSeries_setup_arch using the H_SET_MODE hcall.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
arch/powerpc/kernel/setup_64.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 3d7a50a08f5e1..fbe24377eda3e 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -201,7 +201,8 @@ static void cpu_ready_for_interrupts(void)
get_paca()->kernel_msr = MSR_KERNEL;
/* Enable AIL if supported */
- if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
+ if (cpu_has_feature(CPU_FTR_HVMODE) &&
+ cpu_has_feature(CPU_FTR_ARCH_207S)) {
unsigned long lpcr = mfspr(SPRN_LPCR);
mtspr(SPRN_LPCR, lpcr | LPCR_AIL_3);
}
--
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