Re: [PATCH v2 6/7] KVM: PPC: mmio: Return to guest after emulation failure

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 07/01/2022 07:03, Fabiano Rosas wrote:
> If MMIO emulation fails we don't want to crash the whole guest by
> returning to userspace.
> 
> The original commit bbf45ba57eae ("KVM: ppc: PowerPC 440 KVM
> implementation") added a todo:
> 
>    /* XXX Deliver Program interrupt to guest. */
> 
> and later the commit d69614a295ae ("KVM: PPC: Separate loadstore
> emulation from priv emulation") added the Program interrupt injection
> but in another file, so I'm assuming it was missed that this block
> needed to be altered.
> 
> Signed-off-by: Fabiano Rosas <farosas@linux.ibm.com>


Looks right.
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>

but this means if I want to keep debugging those kvm selftests in 
comfort, I'll have to have some exception handlers in the vm as 
otherwise the failing $pc is lost after this change :)

> ---
>   arch/powerpc/kvm/powerpc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index a2e78229d645..50e08635e18a 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -309,7 +309,7 @@ int kvmppc_emulate_mmio(struct kvm_vcpu *vcpu)
>   		kvmppc_get_last_inst(vcpu, INST_GENERIC, &last_inst);
>   		kvmppc_core_queue_program(vcpu, 0);
>   		pr_info("%s: emulation failed (%08x)\n", __func__, last_inst);
> -		r = RESUME_HOST;
> +		r = RESUME_GUEST;
>   		break;
>   	}
>   	default:

-- 
Alexey