powerpc: Always use SPRN_SPRG_HSCRATCH0 when running in HV mode
This uses feature sections to arrange that we always use HSPRG1
as the scratch register in the interrupt entry code rather than
SPRG2 when we're running in hypervisor mode on POWER7. This will
ensure that we don't trash the guest's SPRG2 when we are running
KVM guests. To simplify the code, we define GET_SCRATCH0() and
SET_SCRATCH0() macros like the GET_PACA/SET_PACA macros.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 13429a0..76d7d5f 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -802,6 +802,20 @@
FTR_SECTION_ELSE_NESTED(66); \
mtspr SPRN_SPRG_HPACA,rX; \
ALT_FTR_SECTION_END_NESTED_IFCLR(CPU_FTR_HVMODE_206, 66)
+
+#define GET_SCRATCH0(rX) \
+ BEGIN_FTR_SECTION_NESTED(66); \
+ mfspr rX,SPRN_SPRG_SCRATCH0; \
+ FTR_SECTION_ELSE_NESTED(66); \
+ mfspr rX,SPRN_SPRG_HSCRATCH0; \
+ ALT_FTR_SECTION_END_NESTED_IFCLR(CPU_FTR_HVMODE_206, 66)
+
+#define SET_SCRATCH0(rX) \
+ BEGIN_FTR_SECTION_NESTED(66); \
+ mtspr SPRN_SPRG_SCRATCH0,rX; \
+ FTR_SECTION_ELSE_NESTED(66); \
+ mtspr SPRN_SPRG_HSCRATCH0,rX; \
+ ALT_FTR_SECTION_END_NESTED_IFCLR(CPU_FTR_HVMODE_206, 66)
#endif
#ifdef CONFIG_PPC_BOOK3E_64