Re: [PATCH v1 1/1] hyperv: Enable SCONTROL if SYNIC is enabled

[Paolo Bonzini]

On 17/07/20 14:56, Jon Doron wrote:
> Based on an analysis of the HyperV firmwares (Gen1 and Gen2) it seems
> like the SCONTROL is not being set to the ENABLED state as like we have
> thought.
> 
> Also from a test done by Vitaly Kuznetsov, running a nested HyperV it
> was concluded that the first access to the SCONTROL MSR with a read
> resulted with the value of 0x1, aka HV_SYNIC_CONTROL_ENABLE.
> 
> It's important to note that this diverges from the value states in the
> HyperV TLFS of 0.
> 
> Signed-off-by: Jon Doron <arilou@gmail.com>
> ---
>  target/i386/kvm.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index b8455c89ed..6a62e8ae94 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -1904,6 +1904,8 @@ void kvm_arch_reset_vcpu(X86CPU *cpu)
>  
>      if (hyperv_feat_enabled(cpu, HYPERV_FEAT_SYNIC)) {
>          int i;
> +
> +        env->msr_hv_synic_control = HV_SYNIC_ENABLE;
>          for (i = 0; i < ARRAY_SIZE(env->msr_hv_synic_sint); i++) {
>              env->msr_hv_synic_sint[i] = HV_SINT_MASKED;
>          }
> 

Are both patches needed or only the Hyper-V one?

Paolo