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Message-ID: <55F934F5.7040605@redhat.com>
Date: Wed, 16 Sep 2015 11:23:01 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Feng Wu <feng.wu@...el.com>, alex.williamson@...hat.com,
joro@...tes.org, mtosatti@...hat.com
Cc: eric.auger@...aro.org, kvm@...r.kernel.org,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 03/13] KVM: Define a new interface
kvm_intr_is_single_vcpu()
On 16/09/2015 10:49, Feng Wu wrote:
> This patch defines a new interface kvm_intr_is_single_vcpu(),
> which can returns whether the interrupt is for single-CPU or not.
>
> It is used by VT-d PI, since now we only support single-CPU
> interrupts, For lowest-priority interrupts, if user configures
> it via /proc/irq or uses irqbalance to make it single-CPU, we
> can use PI to deliver the interrupts to it. Full functionality
> of lowest-priority support will be added later.
>
> Signed-off-by: Feng Wu <feng.wu@...el.com>
> ---
> v8:
> - Some optimizations in kvm_intr_is_single_vcpu().
> - Expose kvm_intr_is_single_vcpu() so we can use it in vmx code.
> - Add kvm_intr_is_single_vcpu_fast() as the fast path to find
> the target vCPU for the single-destination interrupt
>
> arch/x86/include/asm/kvm_host.h | 3 ++
> arch/x86/kvm/irq_comm.c | 94 +++++++++++++++++++++++++++++++++++++++++
> arch/x86/kvm/lapic.c | 5 +--
> arch/x86/kvm/lapic.h | 2 +
> 4 files changed, 101 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 49ec903..af11bca 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1204,4 +1204,7 @@ int __x86_set_memory_region(struct kvm *kvm,
> int x86_set_memory_region(struct kvm *kvm,
> const struct kvm_userspace_memory_region *mem);
>
> +bool kvm_intr_is_single_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq,
> + struct kvm_vcpu **dest_vcpu);
> +
> #endif /* _ASM_X86_KVM_HOST_H */
> diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
> index 9efff9e..97ba1d6 100644
> --- a/arch/x86/kvm/irq_comm.c
> +++ b/arch/x86/kvm/irq_comm.c
> @@ -297,6 +297,100 @@ out:
> return r;
> }
>
> +static bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm,
> + struct kvm_lapic_irq *irq,
> + struct kvm_vcpu **dest_vcpu)
Please put this in lapic.c, similar to kvm_irq_delivery_to_apic_fast, so
that you do not have to export other functions.
> +{
> + struct kvm_apic_map *map;
> + bool ret = false;
> + struct kvm_lapic *dst = NULL;
> +
> + if (irq->shorthand)
> + return false;
> +
> + rcu_read_lock();
> + map = rcu_dereference(kvm->arch.apic_map);
> +
> + if (!map)
> + goto out;
> +
> + if (irq->dest_mode == APIC_DEST_PHYSICAL) {
> + if (irq->dest_id == 0xFF)
> + goto out;
> +
> + if (irq->dest_id >= ARRAY_SIZE(map->phys_map)) {
Warning here is wrong, the guest can trigger it.
> + WARN_ON_ONCE(1);
> + goto out;
> + }
> +
> + dst = map->phys_map[irq->dest_id];
> + if (dst && kvm_apic_present(dst->vcpu))
> + *dest_vcpu = dst->vcpu;
> + else
> + goto out;
> + } else {
> + u16 cid;
> + unsigned long bitmap = 1;
> + int i, r = 0;
> +
> + if (!kvm_apic_logical_map_valid(map)) {
> + WARN_ON_ONCE(1);
Same here.
> + goto out;
> + }
> +
> + apic_logical_id(map, irq->dest_id, &cid, (u16 *)&bitmap);
> +
> + if (cid >= ARRAY_SIZE(map->logical_map)) {
> + WARN_ON_ONCE(1);
Same here.
Otherwise looks good.
Paolo
> + goto out;
> + }
> +
> + for_each_set_bit(i, &bitmap, 16) {
> + dst = map->logical_map[cid][i];
> + if (++r == 2)
> + goto out;
> + }
> +
> + if (dst && kvm_apic_present(dst->vcpu))
> + *dest_vcpu = dst->vcpu;
> + else
> + goto out;
> + }
> +
> + ret = true;
> +out:
> + rcu_read_unlock();
> + return ret;
> +}
> +
> +
> +bool kvm_intr_is_single_vcpu(struct kvm *kvm, struct kvm_lapic_irq *irq,
> + struct kvm_vcpu **dest_vcpu)
> +{
> + int i, r = 0;
> + struct kvm_vcpu *vcpu;
> +
> + if (kvm_intr_is_single_vcpu_fast(kvm, irq, dest_vcpu))
> + return true;
> +
> + kvm_for_each_vcpu(i, vcpu, kvm) {
> + if (!kvm_apic_present(vcpu))
> + continue;
> +
> + if (!kvm_apic_match_dest(vcpu, NULL, irq->shorthand,
> + irq->dest_id, irq->dest_mode))
> + continue;
> +
> + if (++r == 2)
> + return false;
> +
> + *dest_vcpu = vcpu;
> + }
> +
> + return r == 1;
> +}
> +EXPORT_SYMBOL_GPL(kvm_intr_is_single_vcpu);
> +
> #define IOAPIC_ROUTING_ENTRY(irq) \
> { .gsi = irq, .type = KVM_IRQ_ROUTING_IRQCHIP, \
> .u.irqchip = { .irqchip = KVM_IRQCHIP_IOAPIC, .pin = (irq) } }
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 2a5ca97..9848cd50 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -136,13 +136,12 @@ static inline int kvm_apic_id(struct kvm_lapic *apic)
> /* The logical map is definitely wrong if we have multiple
> * modes at the same time. (Physical map is always right.)
> */
> -static inline bool kvm_apic_logical_map_valid(struct kvm_apic_map *map)
> +bool kvm_apic_logical_map_valid(struct kvm_apic_map *map)
> {
> return !(map->mode & (map->mode - 1));
> }
>
> -static inline void
> -apic_logical_id(struct kvm_apic_map *map, u32 dest_id, u16 *cid, u16 *lid)
> +void apic_logical_id(struct kvm_apic_map *map, u32 dest_id, u16 *cid, u16 *lid)
> {
> unsigned lid_bits;
>
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index 7195274..6798b87 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -169,4 +169,6 @@ bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);
>
> void wait_lapic_expire(struct kvm_vcpu *vcpu);
>
> +void apic_logical_id(struct kvm_apic_map *map, u32 dest_id, u16 *cid, u16 *lid);
> +bool kvm_apic_logical_map_valid(struct kvm_apic_map *map);
> #endif
>
--
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