[PATCH v2 03/10] ppc/spapr|pnv: Remove SAO from pa-features

[Nicholas Piggin]

SAO is a page table attribute that strengthens the memory ordering of
accesses. QEMU with MTTCG does not implement this, so clear it in
ibm,pa-features. This is an obscure feature that has been removed from
POWER10 ISA v3.1, there isn't much concern with removing it.

Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/ppc/pnv.c   |  2 +-
 hw/ppc/spapr.c | 14 ++++++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 0b47b92baa..aa9786e970 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -150,7 +150,7 @@ static void pnv_dt_core(PnvChip *chip, PnvCore *pc, void 
*fdt)
     uint32_t page_sizes_prop[64];
     size_t page_sizes_prop_size;
     const uint8_t pa_features[] = { 24, 0,
-                                    0xf6, 0x3f, 0xc7, 0xc0, 0x80, 0xf0,
+                                    0xf6, 0x3f, 0xc7, 0xc0, 0x00, 0xf0,
                                     0x80, 0x00, 0x00, 0x00, 0x00, 0x00,
                                     0x00, 0x00, 0x00, 0x00, 0x80, 0x00,
                                     0x80, 0x00, 0x80, 0x00, 0x80, 0x00 };
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 55263f0815..3108d7c532 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -233,17 +233,23 @@ static void spapr_dt_pa_features(SpaprMachineState *spapr,
                                  PowerPCCPU *cpu,
                                  void *fdt, int offset)
 {
+    /*
+     * SSO (SAO) ordering is supported on KVM and thread=single hosts,
+     * but not MTTCG, so disable it. To advertise it, a cap would have
+     * to be added, or support implemented for MTTCG.
+     */
+
     uint8_t pa_features_206[] = { 6, 0,
-        0xf6, 0x1f, 0xc7, 0x00, 0x80, 0xc0 };
+        0xf6, 0x1f, 0xc7, 0x00, 0x00, 0xc0 };
     uint8_t pa_features_207[] = { 24, 0,
-        0xf6, 0x1f, 0xc7, 0xc0, 0x80, 0xf0,
+        0xf6, 0x1f, 0xc7, 0xc0, 0x00, 0xf0,
         0x80, 0x00, 0x00, 0x00, 0x00, 0x00,
         0x00, 0x00, 0x00, 0x00, 0x80, 0x00,
         0x80, 0x00, 0x80, 0x00, 0x00, 0x00 };
     uint8_t pa_features_300[] = { 66, 0,
         /* 0: MMU|FPU|SLB|RUN|DABR|NX, 1: fri[nzpm]|DABRX|SPRG3|SLB0|PP110 */
-        /* 2: VPM|DS205|PPR|DS202|DS206, 3: LSD|URG, SSO, 5: LE|CFAR|EB|LSQ */
-        0xf6, 0x1f, 0xc7, 0xc0, 0x80, 0xf0, /* 0 - 5 */
+        /* 2: VPM|DS205|PPR|DS202|DS206, 3: LSD|URG, 5: LE|CFAR|EB|LSQ */
+        0xf6, 0x1f, 0xc7, 0xc0, 0x00, 0xf0, /* 0 - 5 */
         /* 6: DS207 */
         0x80, 0x00, 0x00, 0x00, 0x00, 0x00, /* 6 - 11 */
         /* 16: Vector */
-- 
2.42.0