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    SubjectRe: [PATCH v5 10/26] KVM: arm/arm64: GICv4: Wire mapping/unmapping of VLPIs in VFIO irq bypass
    From
    Date
    On 10/11/17 08:28, Christoffer Dall wrote:
    > Hi Eric and Marc,
    >
    > On Tue, Nov 07, 2017 at 02:42:44PM +0000, Marc Zyngier wrote:
    >> Hi Eric,
    >>
    >> On 07/11/17 13:06, Auger Eric wrote:
    >>> Hi Marc,
    >>>
    >>> On 27/10/2017 16:28, Marc Zyngier wrote:
    >>>> Let's use the irq bypass mechanism introduced for platform device
    >>>> interrupts
    >>> nit: I would remove "introduced for platform device interrupts"
    >>> as this is not upstream yet. x86 posted interrupts also use it.
    >>>
    >>>>
    >>> and establish our LPI->VLPI mapping.
    >
    > I have tweaked the commit message.
    >
    >>>>
    >>>> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
    >>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
    >>>> ---
    >>>> include/kvm/arm_vgic.h | 8 ++++
    >>>> virt/kvm/arm/arm.c | 6 ++-
    >>>> virt/kvm/arm/vgic/vgic-v4.c | 108 ++++++++++++++++++++++++++++++++++++++++++++
    >>>> 3 files changed, 120 insertions(+), 2 deletions(-)
    >>>>
    >>>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
    >>>> index 7eeb6c2a2f9c..2f750c770bf2 100644
    >>>> --- a/include/kvm/arm_vgic.h
    >>>> +++ b/include/kvm/arm_vgic.h
    >>>> @@ -373,4 +373,12 @@ int kvm_vgic_setup_default_irq_routing(struct kvm *kvm);
    >>>>
    >>>> int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner);
    >>>>
    >>>> +struct kvm_kernel_irq_routing_entry;
    >>>> +
    >>>> +int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int irq,
    >>>> + struct kvm_kernel_irq_routing_entry *irq_entry);
    >>>> +
    >>>> +int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq,
    >>>> + struct kvm_kernel_irq_routing_entry *irq_entry);
    >>>> +
    >>>> #endif /* __KVM_ARM_VGIC_H */
    >>>> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
    >>>> index 5d5218ecd547..8388c1cc23f6 100644
    >>>> --- a/virt/kvm/arm/arm.c
    >>>> +++ b/virt/kvm/arm/arm.c
    >>>> @@ -1462,7 +1462,8 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons,
    >>>> struct kvm_kernel_irqfd *irqfd =
    >>>> container_of(cons, struct kvm_kernel_irqfd, consumer);
    >>>>
    >>>> - return 0;
    >>>> + return kvm_vgic_v4_set_forwarding(irqfd->kvm, prod->irq,
    >>>> + &irqfd->irq_entry);
    >>>> }
    >>>> void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
    >>>> struct irq_bypass_producer *prod)
    >>>> @@ -1470,7 +1471,8 @@ void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
    >>>> struct kvm_kernel_irqfd *irqfd =
    >>>> container_of(cons, struct kvm_kernel_irqfd, consumer);
    >>>>
    >>>> - return;
    >>>> + kvm_vgic_v4_unset_forwarding(irqfd->kvm, prod->irq,
    >>>> + &irqfd->irq_entry);
    >>>> }
    >>>>
    >>>> void kvm_arch_irq_bypass_stop(struct irq_bypass_consumer *cons)
    >>>> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c
    >>>> index c794f0cef09e..01a2889b7b7c 100644
    >>>> --- a/virt/kvm/arm/vgic/vgic-v4.c
    >>>> +++ b/virt/kvm/arm/vgic/vgic-v4.c
    >>>> @@ -18,6 +18,7 @@
    >>>> #include <linux/interrupt.h>
    >>>> #include <linux/irqdomain.h>
    >>>> #include <linux/kvm_host.h>
    >>>> +#include <linux/irqchip/arm-gic-v3.h>
    >>>>
    >>>> #include "vgic.h"
    >>>>
    >>>> @@ -81,3 +82,110 @@ void vgic_v4_teardown(struct kvm *kvm)
    >>>> its_vm->nr_vpes = 0;
    >>>> its_vm->vpes = NULL;
    >>>> }
    >>>> +
    >>>> +static struct vgic_its *vgic_get_its(struct kvm *kvm,
    >>>> + struct kvm_kernel_irq_routing_entry *irq_entry)
    >>>> +{
    >>>> + struct kvm_msi msi = (struct kvm_msi) {
    >>>> + .address_lo = irq_entry->msi.address_lo,
    >>>> + .address_hi = irq_entry->msi.address_hi,
    >>>> + .data = irq_entry->msi.data,
    >>>> + .flags = irq_entry->msi.flags,
    >>>> + .devid = irq_entry->msi.devid,
    >>>> + };
    >>>> +
    >>>> + /*
    >>>> + * Get a reference on the LPI. If NULL, this is not a valid
    >>>> + * translation for any of our vITSs.
    >>>> + */
    >>> I don't understand the relevance of the above comment.
    >>
    >> Hmmm. The first part looks like an outdated leftover, as the ITS is not
    >> refcounted, and we don't deal with LPIs here.
    >>
    >
    > I simply removed this comment.
    >
    > [...]
    >
    > I think the only thing left to fix on this patch is the IRQ_DISABLE_LAZY
    > thing on its_map_vlpi() failures, which Marc can fix post -rc1.

    Here's what I've queued on the irqchip side:

    From 9c0733704b99c89773416af3a412332b0e8bd2a4 Mon Sep 17 00:00:00 2001
    From: Marc Zyngier <marc.zyngier@arm.com>
    Date: Fri, 10 Nov 2017 09:00:41 +0000
    Subject: [PATCH] irqchip/gic-v4: Clear IRQ_DISABLE_UNLAZY again if mapping
    fails

    Should the call to irq_set_vcpu_affinity() fail at map time,
    we should restore the normal lazy-disable behaviour instead
    of staying with the eager disable that GICv4 requires.

    Reported-by: Eric Auger <eric.auger@redhat.com>
    Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
    ---
    drivers/irqchip/irq-gic-v4.c | 7 ++++++-
    1 file changed, 6 insertions(+), 1 deletion(-)

    diff --git a/drivers/irqchip/irq-gic-v4.c b/drivers/irqchip/irq-gic-v4.c
    index cd0bcc3b7e33..dba9d67cb9c1 100644
    --- a/drivers/irqchip/irq-gic-v4.c
    +++ b/drivers/irqchip/irq-gic-v4.c
    @@ -177,6 +177,7 @@ int its_map_vlpi(int irq, struct its_vlpi_map *map)
    .map = map,
    },
    };
    + int ret;

    /*
    * The host will never see that interrupt firing again, so it
    @@ -184,7 +185,11 @@ int its_map_vlpi(int irq, struct its_vlpi_map *map)
    */
    irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY);

    - return irq_set_vcpu_affinity(irq, &info);
    + ret = irq_set_vcpu_affinity(irq, &info);
    + if (ret)
    + irq_clear_status_flags(irq, IRQ_DISABLE_UNLAZY);
    +
    + return ret;
    }

    int its_get_vlpi(int irq, struct its_vlpi_map *map)
    --
    2.14.2

    Thanks,

    M.
    --
    Jazz is not dead. It just smells funny...

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