Unlike classic, we don't really need the MSR change to be atomic with the
branch. This eliminates a trap as a KVM guest (in the absence of
hardware hypervisor extensions), where mtmsr is paravirtualized but rfi
is not. For a virtualized guest without any paravirtualization, this
eliminates an additional two traps (SRR0/1).
Signed-off-by: Scott Wood <scottw...@freescale.com>
---
arch/powerpc/kernel/entry_32.S | 16 ++++++++++++++++
1 files changed, 16 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index ba3aeb4..6bb637c 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -193,6 +193,9 @@ transfer_to_handler_cont:
lwz r11,0(r9) /* virtual address of handler */
lwz r9,4(r9) /* where to go when done */
#ifdef CONFIG_TRACE_IRQFLAGS
+#ifdef CONFIG_BOOKE
+ mtmsr r10
+#else
lis r12,reenable_mmu@h
ori r12,r12,reenable_mmu@l
mtspr SPRN_SRR0,r12
@@ -201,6 +204,7 @@ transfer_to_handler_cont:
RFI
reenable_mmu: /* re-enable mmu so we can */
mfmsr r10
+#endif /* !CONFIG_BOOKE */
lwz r12,_MSR(r1)
xor r10,r10,r12
andi. r10,r10,MSR_EE /* Did EE change? */
@@ -247,11 +251,23 @@ reenable_mmu: /* re-enable
mmu so we can */
mtlr r9
bctr /* jump to handler */
#else /* CONFIG_TRACE_IRQFLAGS */
+#ifdef CONFIG_BOOKE
+ /*
+ * We're not changing address space on Book E, and the extra rfi
+ * can hurt when virtualized without hardware support -- whereas
+ * mtmsr can be paravirtualized.
+ */
+ mtmsr r10
+ mtctr r11
+ mtlr r9
+ bctr
+#else
mtspr SPRN_SRR0,r11
mtspr SPRN_SRR1,r10
mtlr r9
SYNC
RFI /* jump to handler, enable MMU */
+#endif /* !CONFIG_BOOKE */
#endif /* CONFIG_TRACE_IRQFLAGS */
#if defined (CONFIG_6xx) || defined(CONFIG_E500)
--
1.7.5.4
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
