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Date: Mon, 17 Jan 2022 18:38:23 +0100
From: Pierre Morel <pmorel@...ux.ibm.com>
To: Matthew Rosato <mjrosato@...ux.ibm.com>, linux-s390@...r.kernel.org
Cc: alex.williamson@...hat.com, cohuck@...hat.com,
schnelle@...ux.ibm.com, farman@...ux.ibm.com,
borntraeger@...ux.ibm.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
frankja@...ux.ibm.com, david@...hat.com, imbrenda@...ux.ibm.com,
vneethv@...ux.ibm.com, oberpar@...ux.ibm.com, freude@...ux.ibm.com,
thuth@...hat.com, pasic@...ux.ibm.com, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 16/30] KVM: s390: pci: enable host forwarding of
Adapter Event Notifications
On 1/14/22 21:31, Matthew Rosato wrote:
> In cases where interrupts are not forwarded to the guest via firmware,
> KVM is responsible for ensuring delivery. When an interrupt presents
> with the forwarding bit, we must process the forwarding tables until
> all interrupts are delivered.
>
> Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
> ---
> arch/s390/include/asm/kvm_host.h | 1 +
> arch/s390/include/asm/tpi.h | 13 ++++++
> arch/s390/kvm/interrupt.c | 76 +++++++++++++++++++++++++++++++-
> arch/s390/kvm/kvm-s390.c | 3 +-
> arch/s390/kvm/pci.h | 9 ++++
> 5 files changed, 100 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index a604d51acfc8..3f147b8d050b 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -757,6 +757,7 @@ struct kvm_vm_stat {
> u64 inject_pfault_done;
> u64 inject_service_signal;
> u64 inject_virtio;
> + u64 aen_forward;
> };
>
> struct kvm_arch_memory_slot {
> diff --git a/arch/s390/include/asm/tpi.h b/arch/s390/include/asm/tpi.h
> index 1ac538b8cbf5..f76e5fdff23a 100644
> --- a/arch/s390/include/asm/tpi.h
> +++ b/arch/s390/include/asm/tpi.h
> @@ -19,6 +19,19 @@ struct tpi_info {
> u32 :12;
> } __packed __aligned(4);
>
> +/* I/O-Interruption Code as stored by TPI for an Adapter I/O */
> +struct tpi_adapter_info {
> + u32 aism:8;
> + u32 :22;
> + u32 error:1;
> + u32 forward:1;
> + u32 reserved;
> + u32 adapter_IO:1;
> + u32 directed_irq:1;
> + u32 isc:3;
> + u32 :27;
> +} __packed __aligned(4);
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_S390_TPI_H */
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index a591b8cd662f..07743c6a67c4 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -3263,11 +3263,85 @@ int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
> }
> EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
>
> +static void aen_host_forward(unsigned long si)
> +{
> + struct kvm_s390_gisa_interrupt *gi;
> + struct zpci_gaite *gaite;
> + struct kvm *kvm;
> +
> + gaite = (struct zpci_gaite *)aift->gait +
> + (si * sizeof(struct zpci_gaite));
> + if (gaite->count == 0)
> + return;
> + if (gaite->aisb != 0)
> + set_bit_inv(gaite->aisbo, (unsigned long *)gaite->aisb);
> +
> + kvm = kvm_s390_pci_si_to_kvm(aift, si);
> + if (kvm == 0)
> + return;
> + gi = &kvm->arch.gisa_int;
> +
> + if (!(gi->origin->g1.simm & AIS_MODE_MASK(gaite->gisc)) ||
> + !(gi->origin->g1.nimm & AIS_MODE_MASK(gaite->gisc))) {
> + gisa_set_ipm_gisc(gi->origin, gaite->gisc);
> + if (hrtimer_active(&gi->timer))
> + hrtimer_cancel(&gi->timer);
> + hrtimer_start(&gi->timer, 0, HRTIMER_MODE_REL);
> + kvm->stat.aen_forward++;
> + }
> +}
> +
> +static void aen_process_gait(u8 isc)
> +{
> + bool found = false, first = true;
> + union zpci_sic_iib iib = {{0}};
> + unsigned long si, flags;
> +
> + spin_lock_irqsave(&aift->gait_lock, flags);
> +
> + if (!aift->gait) {
> + spin_unlock_irqrestore(&aift->gait_lock, flags);
> + return;
> + }
> +
> + for (si = 0;;) {
> + /* Scan adapter summary indicator bit vector */
> + si = airq_iv_scan(aift->sbv, si, airq_iv_end(aift->sbv));
> + if (si == -1UL) {
> + if (first || found) {
> + /* Reenable interrupts. */
> + if (zpci_set_irq_ctrl(SIC_IRQ_MODE_SINGLE, isc,
> + &iib))
> + break;
AFAIU this code is VFIO interpretation specific code and facility 12 is
a precondition for it, so I think this break will never occur.
If I am right we should not test the return value which will make the
code clearer.
> + first = found = false;
> + } else {
> + /* Interrupts on and all bits processed */
> + break;
> + }
May be add a comment: "rescan after re-enabling interrupts"
> + found = false;
> + si = 0;
> + continue;
> + }
> + found = true;
> + aen_host_forward(si);
> + }
> +
> + spin_unlock_irqrestore(&aift->gait_lock, flags);
> +}
> +
> static void gib_alert_irq_handler(struct airq_struct *airq,
> struct tpi_info *tpi_info)
> {
> + struct tpi_adapter_info *info = (struct tpi_adapter_info *)tpi_info;
> +
> inc_irq_stat(IRQIO_GAL);
> - process_gib_alert_list();
> +
> + if (IS_ENABLED(CONFIG_PCI) && (info->forward || info->error)) {
> + aen_process_gait(info->isc);
> + if (info->aism != 0)
> + process_gib_alert_list();
> + } else
> + process_gib_alert_list();
NIT: I think we need braces around this statement
> }
>
> static struct airq_struct gib_alert_irq = {
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 01dc3f6883d0..ab8b56deed11 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -65,7 +65,8 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
> STATS_DESC_COUNTER(VM, inject_float_mchk),
> STATS_DESC_COUNTER(VM, inject_pfault_done),
> STATS_DESC_COUNTER(VM, inject_service_signal),
> - STATS_DESC_COUNTER(VM, inject_virtio)
> + STATS_DESC_COUNTER(VM, inject_virtio),
> + STATS_DESC_COUNTER(VM, aen_forward)
> };
>
> const struct kvm_stats_header kvm_vm_stats_header = {
> diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h
> index b2000ed7b8c3..387b637863c9 100644
> --- a/arch/s390/kvm/pci.h
> +++ b/arch/s390/kvm/pci.h
> @@ -12,6 +12,7 @@
>
> #include <linux/pci.h>
> #include <linux/mutex.h>
> +#include <linux/kvm_host.h>
> #include <asm/airq.h>
> #include <asm/kvm_pci.h>
>
> @@ -34,6 +35,14 @@ struct zpci_aift {
>
> extern struct zpci_aift *aift;
>
> +static inline struct kvm *kvm_s390_pci_si_to_kvm(struct zpci_aift *aift,
> + unsigned long si)
> +{
> + if (!IS_ENABLED(CONFIG_PCI) || aift->kzdev == 0 || aift->kzdev[si] == 0)
Shouldn't it be better CONFIG_VFIO_PCI ?
> + return 0;
> + return aift->kzdev[si]->kvm;
> +};
> +
> int kvm_s390_pci_aen_init(u8 nisc);
> void kvm_s390_pci_aen_exit(void);
>
>
--
Pierre Morel
IBM Lab Boeblingen
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