Alexander Graf <agraf@xxxxxxx> writes:
> On 05.06.14 14:08, Aneesh Kumar K.V wrote:
>> We don't have SMT support yet, hence we should not find a doorbell
>> message generated
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>> ---
>> arch/powerpc/kvm/book3s_emulate.c | 18 ++++++++++++++++++
>> 1 file changed, 18 insertions(+)
>>
>> diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
>> index 1bb16a59dcbc..d6c87d085182 100644
>> --- a/arch/powerpc/kvm/book3s_emulate.c
>> +++ b/arch/powerpc/kvm/book3s_emulate.c
>> @@ -28,7 +28,9 @@
>> #define OP_19_XOP_RFI 50
>>
>> #define OP_31_XOP_MFMSR 83
>> +#define OP_31_XOP_MSGSNDP 142
>> #define OP_31_XOP_MTMSR 146
>> +#define OP_31_XOP_MSGCLRP 174
>> #define OP_31_XOP_MTMSRD 178
>> #define OP_31_XOP_MTSR 210
>> #define OP_31_XOP_MTSRIN 242
>> @@ -303,6 +305,22 @@ int kvmppc_core_emulate_op_pr(struct kvm_run *run, struct kvm_vcpu *vcpu,
>>
>> break;
>> }
>> + case OP_31_XOP_MSGSNDP:
>> + {
>> + /*
>> + * PR KVM still don't support SMT mode. So we should
>
> still?
>
>> + * not see a MSGSNDP/MSGCLRP used with PR KVM
>> + */
>> + pr_info("KVM: MSGSNDP used in non SMT case\n");
>> + emulated = EMULATE_FAIL;
>
> What would happen on an HV guest with only 1 thread that MSGSNDs to
> thread 0? Would the guest get an illegal instruction trap, a
> self-interrupt or would this be a simple nop?
>
We do get a self-interrupt. I tried the below
tag = mfspr(SPRN_TIR) & 0x7f;
ppc_msgsnd(5, 0, tag);
And that results in doorbell exception. That implies we will have to
have full implementation of doorbell. You can drop patch 2 and 3 from
this series. I will rework them.
NOTE: This is not an issue for Linux guest, because we don't send ipi
to self. But to complete the emulation of msgsndp we will need to
emulate it properly.
-aneesh
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