[Qemu-devel] [PATCH 2/2] spapr: Better handling of ibm, pa-features TM bit

[Anton Blanchard]

From: Anton Blanchard <an...@samba.org>

There are a few issues with our handling of the ibm,pa-features
TM bit:

- We don't support transactional memory in PR KVM, so don't tell
  the OS that we do.

- In full emulation we have a minimal implementation of TM that always
  fails, so for performance reasons lets not tell the OS that we
  support it either.

- In HV KVM mode, we should mirror the host TM enabled state by
  looking at the AT_HWCAP2 bit.

Signed-off-by: Anton Blanchard <an...@samba.org>
---

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 0636642..c403fbb 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -620,7 +620,7 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, 
int offset,
         0xf6, 0x1f, 0xc7, 0xc0, 0x80, 0xf0,
         0x80, 0x00, 0x00, 0x00, 0x00, 0x00,
         0x00, 0x00, 0x00, 0x00, 0x80, 0x00,
-        0x80, 0x00, 0x80, 0x00, 0x80, 0x00 };
+        0x80, 0x00, 0x80, 0x00, 0x00, 0x00 };
     uint8_t *pa_features;
     size_t pa_size;
 
@@ -697,6 +697,19 @@ static void spapr_populate_cpu_dt(CPUState *cs, void *fdt, 
int offset,
     } else /* env->mmu_model == POWERPC_MMU_2_07 */ {
         pa_features = pa_features_207;
         pa_size = sizeof(pa_features_207);
+
+#ifdef CONFIG_KVM
+        /* Only enable TM in HV KVM mode */
+        if (kvm_enabled() &&
+            !kvm_vm_check_extension(cs->kvm_state, KVM_CAP_PPC_GET_PVINFO)) {
+            unsigned long hwcap2 = qemu_getauxval(AT_HWCAP2);
+
+            /* Guest should inherit host TM enabled bit */
+            if (hwcap2 & PPC_FEATURE2_HAS_HTM) {
+                pa_features[24] |= 0x80;
+            }
+        }
+#endif
     }
     if (env->ci_large_pages) {
         pa_features[3] |= 0x20;