[PATCH v11 5/5] i386: Remove generic SMT thread check

Babu Moger
2018-05-24T15:43:34Z

Remove generic non-intel check while validating hyperthreading support.
Certain AMD CPUs can support hyperthreading now.

CPU family with TOPOEXT feature can support hyperthreading now.

Signed-off-by: Babu Moger <babu.moger@amd.com>
Tested-by: Geoffrey McRae <geoff@hostfission.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
---
target/i386/cpu.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 0b62356..e09eedb 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -4951,17 +4951,20 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)

qemu_init_vcpu(cs);

- /* Only Intel CPUs support hyperthreading. Even though QEMU fixes this
- * issue by adjusting CPUID_0000_0001_EBX and CPUID_8000_0008_ECX
- * based on inputs (sockets,cores,threads), it is still better to gives
+ /* Most Intel and certain AMD CPUs support hyperthreading. Even though QEMU
+ * fixes this issue by adjusting CPUID_0000_0001_EBX and CPUID_8000_0008_ECX
+ * based on inputs (sockets,cores,threads), it is still better to give
* users a warning.
*
* NOTE: the following code has to follow qemu_init_vcpu(). Otherwise
* cs->nr_threads hasn't be populated yet and the checking is incorrect.
*/
- if (!IS_INTEL_CPU(env) && cs->nr_threads > 1 && !ht_warned) {
- error_report("AMD CPU doesn't support hyperthreading. Please configure"
- " -smp options properly.");
+ if (IS_AMD_CPU(env) &&
+ !(env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_TOPOEXT) &&
+ cs->nr_threads > 1 && !ht_warned) {
+ error_report("This family of AMD CPU doesn't support "
+ "hyperthreading(%d). Please configure -smp "
+ "options properly.", cs->nr_threads);
ht_warned = true;
}

--
1.8.3.1