[PATCH] ppc: Add stub implementation of TRIG SPRs

[Joel Stanley]

Linux sets these to control cache flush behaviour on Power9. Supervisor
and hypervisor are allowed to write, and reads are noops.

Add implementations to avoid noisy messages when booting Linux under the
pseries machine with guest_errors enabled.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 target/ppc/cpu.h      |  2 ++
 target/ppc/cpu_init.c | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
index 25fac9577aa4..6826702ea658 100644
--- a/target/ppc/cpu.h
+++ b/target/ppc/cpu.h
@@ -1897,7 +1897,9 @@ void ppc_compat_add_property(Object *obj, const char 
*name,
 #define SPR_PSSCR             (0x357)
 #define SPR_440_INV0          (0x370)
 #define SPR_440_INV1          (0x371)
+#define SPR_TRIG1             (0x371)
 #define SPR_440_INV2          (0x372)
+#define SPR_TRIG2             (0x372)
 #define SPR_440_INV3          (0x373)
 #define SPR_440_ITV0          (0x374)
 #define SPR_440_ITV1          (0x375)
diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
index 02b7aad9b0e3..3b6ccb5ea4e6 100644
--- a/target/ppc/cpu_init.c
+++ b/target/ppc/cpu_init.c
@@ -5660,6 +5660,16 @@ static void register_power_common_book4_sprs(CPUPPCState 
*env)
                  SPR_NOACCESS, SPR_NOACCESS,
                  &spr_read_tfmr, &spr_write_tfmr,
                  0x00000000);
+    spr_register_hv(env, SPR_TRIG1, "TRIG1",
+                 SPR_NOACCESS, SPR_NOACCESS,
+                 &spr_access_nop, &spr_write_generic,
+                 &spr_access_nop, &spr_write_generic,
+                 0x00000000);
+    spr_register_hv(env, SPR_TRIG2, "TRIG2",
+                 SPR_NOACCESS, SPR_NOACCESS,
+                 &spr_access_nop, &spr_write_generic,
+                 &spr_access_nop, &spr_write_generic,
+                 0x00000000);
 #endif
 }
 
-- 
2.40.1