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Date: Thu, 17 Sep 2015 03:17:03 +0000
From: "Wu, Feng" <feng.wu@...el.com>
To: Paolo Bonzini <pbonzini@...hat.com>,
"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
"joro@...tes.org" <joro@...tes.org>,
"mtosatti@...hat.com" <mtosatti@...hat.com>
CC: "eric.auger@...aro.org" <eric.auger@...aro.org>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Wu, Feng" <feng.wu@...el.com>
Subject: RE: [PATCH v8 03/13] KVM: Define a new interface
kvm_intr_is_single_vcpu()
> -----Original Message-----
> From: Paolo Bonzini [mailto:pbonzini@...hat.com]
> Sent: Wednesday, September 16, 2015 5:23 PM
> To: Wu, Feng; 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.
Could you please share more information about how the guest
triggers these conditions (including the following two), Thanks
a lot!
Thanks,
Feng
>
> > + 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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