[Qemu-devel] [PATCH 3/3] ppc: Check the availability of transactional memory

[Thomas Huth <thuth@redhat.com>]

KVM-PR currently does not support transactional memory, and the
implementation in TCG is just a fake. We should not announce TM
support in the ibm,pa-features property when running on such a
system, so disable it by default and only enable it if the KVM
implementation supports it (i.e. recent versions of KVM-HV).
These changes are based on some earlier work from Anton Blanchard
(thanks!).

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 hw/ppc/spapr.c       | 5 ++++-
 target-ppc/kvm.c     | 7 +++++++
 target-ppc/kvm_ppc.h | 6 ++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 46d6b90..0bdea5b 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -555,7 +555,7 @@ static void spapr_populate_pa_features(CPUPPCState *env, 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;
 
@@ -584,6 +584,9 @@ static void spapr_populate_pa_features(CPUPPCState *env, void *fdt, int offset)
          */
         pa_features[3] |= 0x20;
     }
+    if (kvmppc_has_cap_htm()) {
+        pa_features[24] |= 0x80;    /* Transactional memory support */
+    }
 
     _FDT((fdt_setprop(fdt, offset, "ibm,pa-features", pa_features, pa_size)));
 }
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index a18d4d5..e9a9faf 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -80,6 +80,7 @@ static int cap_ppc_watchdog;
 static int cap_papr;
 static int cap_htab_fd;
 static int cap_fixup_hcalls;
+static int cap_htm;             /* Hardware transactional memory support */
 
 static uint32_t debug_inst_opcode;
 
@@ -122,6 +123,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
      * only activated after this by kvmppc_set_papr() */
     cap_htab_fd = kvm_check_extension(s, KVM_CAP_PPC_HTAB_FD);
     cap_fixup_hcalls = kvm_check_extension(s, KVM_CAP_PPC_FIXUP_HCALL);
+    cap_htm = kvm_vm_check_extension(s, KVM_CAP_PPC_HTM);
 
     if (!cap_interrupt_level) {
         fprintf(stderr, "KVM: Couldn't find level irq capability. Expect the "
@@ -2353,6 +2355,11 @@ bool kvmppc_has_cap_fixup_hcalls(void)
     return cap_fixup_hcalls;
 }
 
+bool kvmppc_has_cap_htm(void)
+{
+    return cap_htm;
+}
+
 static PowerPCCPUClass *ppc_cpu_get_family_class(PowerPCCPUClass *pcc)
 {
     ObjectClass *oc = OBJECT_CLASS(pcc);
diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index a778184..bd1d78b 100644
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -55,6 +55,7 @@ void kvmppc_hash64_free_pteg(uint64_t token);
 void kvmppc_hash64_write_pte(CPUPPCState *env, target_ulong pte_index,
                              target_ulong pte0, target_ulong pte1);
 bool kvmppc_has_cap_fixup_hcalls(void);
+bool kvmppc_has_cap_htm(void);
 int kvmppc_enable_hwrng(void);
 int kvmppc_put_books_sregs(PowerPCCPU *cpu);
 PowerPCCPUClass *kvm_ppc_get_host_cpu_class(void);
@@ -249,6 +250,11 @@ static inline bool kvmppc_has_cap_fixup_hcalls(void)
     abort();
 }
 
+static inline bool kvmppc_has_cap_htm(void)
+{
+    return false;
+}
+
 static inline int kvmppc_enable_hwrng(void)
 {
     return -1;
-- 
1.8.3.1