On 25.10.18 14:37, Michael Mueller wrote:
> The GIB (Guest Information Block) links the GISA of all guests
> that have adapter interrupts pending. These interrupts cannot be
> deliverd because no vcpu of these guests is currently running in
> SIE context. Instead, a GIB alert is issued on the host to schedule
> these guests to run.
>
> This mechanism allows to process adapter interrupts for currently
> not running guests.
>
> The GIB is created during host initialization and associated with
> the Adapter Interruption Facility in case an Adapter Interruption
> Virtualization Facility is available.
>
> Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> +void kvm_s390_gib_init(u8 nisc)
> +{
> + int rc;
> +
> + if (gib)
> + return;
Given that we call this function from kvm_arch_init(), why do you expect
this check to ever be true?
> +
> + if (!css_general_characteristics.aiv) {
> + KVM_EVENT(3, "%s", "gib not initialized, no AIV facility");
> + return;
> + }
> +
> + gib = (struct kvm_s390_gib *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
> + if (!gib) {
> + KVM_EVENT(3, "%s", "gib memory allocation failed");
> + return;
> + }
> +
> + gib->nisc = nisc;
> + rc = chsc_sgib((u32)(u64)gib);
> + if (rc) {
> + KVM_EVENT(3, "gib 0x%pK AIV association failed rc: %d",
> + gib, rc);
> + free_page((unsigned long)gib);
> + gib = NULL;
> + return;
> + }
> +
> + KVM_EVENT(3, "gib 0x%pK (nisc=%d) initialized", gib, gib->nisc);
> +}
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index ac5da6b0b862..c75b01856092 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -433,6 +433,7 @@ int kvm_arch_init(void *opaque)
>
> void kvm_arch_exit(void)
> {
> + kvm_s390_gib_destroy();
> debug_unregister(kvm_s390_dbf);
> }
>
> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
> index 981e3ba97461..5983800d6433 100644
> --- a/arch/s390/kvm/kvm-s390.h
> +++ b/arch/s390/kvm/kvm-s390.h
> @@ -380,6 +380,8 @@ int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu,
> void kvm_s390_gisa_init(struct kvm *kvm);
> void kvm_s390_gisa_clear(struct kvm *kvm);
> void kvm_s390_gisa_destroy(struct kvm *kvm);
> +void kvm_s390_gib_init(u8 nisc);
> +void kvm_s390_gib_destroy(void);
>
> /* implemented in guestdbg.c */
> void kvm_s390_backup_guest_per_regs(struct kvm_vcpu *vcpu);
>
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