On Fri, 30 Nov 2018 15:32:14 +0100
Michael Mueller <mimu@xxxxxxxxxxxxx> wrote:
> The patch implements a handler for GIB alert interruptions
> on the host. Its task is to alert storage backed guests that
What is "storage backed" in this context? Aren't all our guests storage
backed?
> interrupts are pending for them.
>
> A GIB alert interrupt statistic counter is added as well:
>
> $ cat /proc/interrupts
> CPU0 CPU1
> ...
> GAL: 23 37 [I/O] GIB Alert
> ...
>
> Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
> ---
> arch/s390/include/asm/irq.h | 1 +
> arch/s390/include/asm/isc.h | 1 +
> arch/s390/kernel/irq.c | 1 +
> arch/s390/kvm/interrupt.c | 66 ++++++++++++++++++++++++++++++++++++++-------
> arch/s390/kvm/kvm-s390.h | 5 ++++
> 5 files changed, 65 insertions(+), 9 deletions(-)
>
> @@ -2953,6 +2965,9 @@ static void __maybe_unused process_gib_alert_list(void)
> void kvm_s390_gisa_clear(struct kvm *kvm)
> {
> if (kvm->arch.gisa) {
> + kvm->arch.gisa->iam = 0;
> + while (in_alert_list(kvm->arch.gisa))
> + process_gib_alert_list();
I'm a bit confused. Isn't process_gib_alert_list() to continue
processing until millicode stops adding alerts? Why do you need the
outer while loop, then?
> nullify_gisa(kvm->arch.gisa);
> VM_EVENT(kvm, 3, "gisa 0x%pK cleared", kvm->arch.gisa);
> }
> @@ -2964,9 +2979,9 @@ void kvm_s390_gisa_init(struct kvm *kvm)
> kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
> kvm->arch.iam = 0;
> spin_lock_init(&kvm->arch.iam_ref_lock);
> - VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
> - kvm_s390_gisa_clear(kvm);
> + nullify_gisa(kvm->arch.gisa);
Why this change? The only difference here is that the unneeded check
for gisa != NULL is not happening, and the dbf event for clearing is
not logged?
> kvm->arch.gib_in_use = !!gib;
> + VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
> }
> }
>
> @@ -2974,6 +2989,10 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
> {
> if (!kvm->arch.gisa)
> return;
> +
> + kvm->arch.gisa->iam = 0;
> + while (in_alert_list(kvm->arch.gisa))
> + process_gib_alert_list();
Same comment as above. I feel like I'm missing something obvious :(
> kvm->arch.gisa = NULL;
> kvm->arch.iam = 0;
> }
> int kvm_s390_gib_init(u8 nisc)
> {
> + int rc = 0;
> +
> if (!css_general_characteristics.aiv) {
> KVM_EVENT(3, "%s", "gib not initialized, no AIV facility");
> - return 0;
> + goto out;
Would be easier to read if you had used the 'goto out' pattern from the
beginning :(
> }
>
> gib = (struct kvm_s390_gib *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
> if (!gib) {
> KVM_EVENT(3, "gib 0x%pK memory allocation failed", gib);
> - return -ENOMEM;
> + rc = -ENOMEM;
> + goto out;
> + }
> +
> + gib_alert_irq.isc = nisc;
> + if (register_adapter_interrupt(&gib_alert_irq)) {
> + KVM_EVENT(3, "gib 0x%pK GAI registration failed", gib);
I think this should be logged to the syslog as well, so you can find
out what went wrong for modular kvm.
> + rc = -EIO;
> + goto out_free;
> }
>
> gib->nisc = nisc;
> if (chsc_sgib((u32)(u64)gib)) {
> KVM_EVENT(3, "gib 0x%pK AIV association failed", gib);
> - free_page((unsigned long)gib);
> - gib = NULL;
> - return -EIO;
> + rc = -EIO;
> + goto out_unreg;
> }
>
> KVM_EVENT(3, "gib 0x%pK (nisc=%d) initialized", gib, gib->nisc);
> - return 0;
> + return rc;
> +
> +out_unreg:
> + unregister_adapter_interrupt(&gib_alert_irq);
> +out_free:
> + free_page((unsigned long)gib);
> + gib = NULL;
> +out:
> + return rc;
> }
