Re: [PATCH v2 1/2] s390/kvm: fix diag318 reset

[Janosch Frank <frankja@linux.ibm.com>]

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On 10/15/20 9:59 PM, Collin Walling wrote:
> The DIAGNOSE 0x0318 instruction must be reset on a normal and clear
> reset. However, this was missed for the clear reset case.
> 
> Let's fix this by resetting the information during a normal reset. 
> Since clear reset is a superset of normal reset, the info will
> still reset on a clear reset.

The architecture really confuses me here but I think we don't want this
in the kernel VCPU reset handlers at all.

This needs to be reset per VM *NOT* per VCPU.
Hence the resets are bound to diag308 and not SIGP.

I.e. we need to clear it in QEMU's VM reset handler.
It's still early and I have yet to consume my first coffee, am I missing
something?

> 
> Signed-off-by: Collin Walling <walling@linux.ibm.com>
> ---
>  arch/s390/kvm/kvm-s390.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 6b74b92c1a58..b0cf8367e261 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -3516,6 +3516,7 @@ static void kvm_arch_vcpu_ioctl_normal_reset(struct kvm_vcpu *vcpu)
>  	vcpu->arch.sie_block->gpsw.mask &= ~PSW_MASK_RI;
>  	vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
>  	memset(vcpu->run->s.regs.riccb, 0, sizeof(vcpu->run->s.regs.riccb));
> +	vcpu->run->s.regs.diag318 = 0;
>  
>  	kvm_clear_async_pf_completion_queue(vcpu);
>  	if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
> @@ -3582,7 +3583,6 @@ static void kvm_arch_vcpu_ioctl_clear_reset(struct kvm_vcpu *vcpu)
>  
>  	regs->etoken = 0;
>  	regs->etoken_extension = 0;
> -	regs->diag318 = 0;
>  }
>  
>  int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> 



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