Re: [PATCH v5 14/15] KVM: s390: add and wire function gib_alert_irq_handler()

Pierre Morel
2019-01-03T15:16:19Z

On 19/12/2018 20:17, Michael Mueller wrote:
> The patch implements a handler for GIB alert interruptions
> on the host. Its task is to alert guests that 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@linux.ibm.com>
> ---
> 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 | 36 ++++++++++++++++++++++++++++++++++--
> 4 files changed, 37 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/include/asm/irq.h b/arch/s390/include/asm/irq.h
> index 2f7f27e5493f..afaf5e3c57fd 100644
> --- a/arch/s390/include/asm/irq.h
> +++ b/arch/s390/include/asm/irq.h
> @@ -62,6 +62,7 @@ enum interruption_class {
> IRQIO_MSI,
> IRQIO_VIR,
> IRQIO_VAI,
> + IRQIO_GAL,
> NMI_NMI,
> CPU_RST,
> NR_ARCH_IRQS
> diff --git a/arch/s390/include/asm/isc.h b/arch/s390/include/asm/isc.h
> index 6cb9e2ed05b6..b2cc1ec78d06 100644
> --- a/arch/s390/include/asm/isc.h
> +++ b/arch/s390/include/asm/isc.h
> @@ -21,6 +21,7 @@
> /* Adapter interrupts. */
> #define QDIO_AIRQ_ISC IO_SCH_ISC /* I/O subchannel in qdio mode */
> #define PCI_ISC 2 /* PCI I/O subchannels */
> +#define GAL_ISC 5 /* GIB alert */
> #define AP_ISC 6 /* adjunct processor (crypto) devices */
>
> /* Functions for registration of I/O interruption subclasses */
> diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
> index 0e8d68bac82c..0cd5a5f96729 100644
> --- a/arch/s390/kernel/irq.c
> +++ b/arch/s390/kernel/irq.c
> @@ -88,6 +88,7 @@ static const struct irq_class irqclass_sub_desc[] = {
> {.irq = IRQIO_MSI, .name = "MSI", .desc = "[I/O] MSI Interrupt" },
> {.irq = IRQIO_VIR, .name = "VIR", .desc = "[I/O] Virtual I/O Devices"},
> {.irq = IRQIO_VAI, .name = "VAI", .desc = "[I/O] Virtual I/O Devices AI"},
> + {.irq = IRQIO_GAL, .name = "GAL", .desc = "[I/O] GIB Alert"},
> {.irq = NMI_NMI, .name = "NMI", .desc = "[NMI] Machine Check"},
> {.irq = CPU_RST, .name = "RST", .desc = "[CPU] CPU Restart"},
> };
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index 03e7ba4f215a..79b9c262479b 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -26,6 +26,7 @@
> #include <asm/gmap.h>
> #include <asm/switch_to.h>
> #include <asm/nmi.h>
> +#include <asm/airq.h>
> #include "kvm-s390.h"
> #include "gaccess.h"
> #include "trace-s390.h"
> @@ -3043,7 +3044,7 @@ static void __floating_airqs_kick(struct kvm *kvm)
> #define NONE_GISA_ADDR 0x00000001UL
> #define GISA_ADDR_MASK 0xfffff000UL
>
> -static void __maybe_unused process_gib_alert_list(void)
> +static void process_gib_alert_list(void)
> {
> u32 final, next_alert, origin = 0UL;
> struct kvm_s390_gisa *gisa;
> @@ -3091,7 +3092,10 @@ void kvm_s390_gisa_clear(struct kvm *kvm)
> {
> if (!kvm->arch.gisa)
> return;
> + if (set_iam(kvm->arch.gisa, 0) == -EBUSY)
> + process_gib_alert_list();

We call process_gib_alert_list() from different contexts shouldn't we
protect the calls?

> nullify_gisa(kvm->arch.gisa);
> + set_iam(kvm->arch.gisa, kvm->arch.iam);
> VM_EVENT(kvm, 3, "gisa 0x%pK cleared", kvm->arch.gisa);
> }
>
> @@ -3111,6 +3115,8 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
> {
> if (!kvm->arch.gisa)
> return;
> + if (set_iam(kvm->arch.gisa, 0) == -EBUSY)
> + process_gib_alert_list();

idem.

> kvm->arch.gisa = NULL;
> }
>
> @@ -3159,11 +3165,23 @@ int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
> }
> EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
>
> +static void gib_alert_irq_handler(struct airq_struct *airq)
> +{
> + inc_irq_stat(IRQIO_GAL);
> + process_gib_alert_list();

idem.

> +}
> +
> +static struct airq_struct gib_alert_irq = {
> + .handler = gib_alert_irq_handler,
> + .lsi_ptr = &gib_alert_irq.lsi_mask,
> +};
> +
> void kvm_s390_gib_destroy(void)
> {
> if (!gib)
> return;
> chsc_sgib(0);
> + unregister_adapter_interrupt(&gib_alert_irq);
> free_page((unsigned long)gib);
> gib = NULL;
> }
> @@ -3183,16 +3201,30 @@ int kvm_s390_gib_init(u8 nisc)
> goto out;
> }
>
> + gib_alert_irq.isc = nisc;
> + if (register_adapter_interrupt(&gib_alert_irq)) {
> + pr_err("Registering the GIB alert interruption handler failed\n");
> + rc = -EIO;
> + goto out_free;
> + }
> +
> gib->nisc = nisc;
> if (chsc_sgib((u32)(u64)gib)) {
> pr_err("Associating the GIB with the AIV facility failed\n");
> free_page((unsigned long)gib);
> gib = NULL;
> rc = -EIO;
> - goto out;
> + goto out_unreg;
> }
>
> KVM_EVENT(3, "gib 0x%pK (nisc=%d) initialized", gib, gib->nisc);
> + goto out;
> +
> +out_unreg:
> + unregister_adapter_interrupt(&gib_alert_irq);
> +out_free:
> + free_page((unsigned long)gib);
> + gib = NULL;
> out:
> return rc;
> }
>

--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany