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Subject[PATCH 3/3] powernv:idle: Set LPCR_UPRT on wakeup from deep-stop
Date
From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>

On wakeup from a deep-stop used for CPU-Hotplug, we invoke
cur_cpu_spec->cpu_restore() which would set sane default values to
various SPRs including LPCR.

On POWER9, the cpu_restore_power9() call would would restore LPCR to a
sane value that is set at early boot time, thereby clearing LPCR_UPRT.

However, LPCR_UPRT is required to be set if we are running in Radix
mode. If this is not set we will end up with a crash when we enable
IR,DR.

To fix this, after returning from cur_cpu_spec->cpu_restore() in the
idle exit path, set LPCR_UPRT if we are running in Radix mode.

Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
---
arch/powerpc/kernel/idle_book3s.S | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 6a9bd28..39a9b63 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -804,6 +804,19 @@ no_segments:
#endif
mtctr r12
bctrl
+/*
+ * cur_cpu_spec->cpu_restore would restore LPCR to a
+ * sane value that is set at early boot time,
+ * thereby clearing LPCR_UPRT.
+ * LPCR_UPRT is required if we are running in Radix mode.
+ * Set it here if that be the case.
+ */
+BEGIN_MMU_FTR_SECTION
+ mfspr r3, SPRN_LPCR
+ LOAD_REG_IMMEDIATE(r4, LPCR_UPRT)
+ or r3, r3, r4
+ mtspr SPRN_LPCR, r3
+END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX)

hypervisor_state_restored:

--
1.9.4
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