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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC PATCH 08/24] ARM: GICv3: introduce separate pending_irq structs for LPIs
On Wed, Sep 28, 2016 at 11:54 PM, Andre Przywara <andre.przywara@xxxxxxx> wrote:
> For the same reason that allocating a struct irq_desc for each
> possible LPI is not an option, having a struct pending_irq for each LPI
> is also not feasible. However we actually only need those when an
> interrupt is on a vCPU (or is about to be injected).
> Maintain a list of those structs that we can use for the lifecycle of
> a guest LPI. We allocate new entries if necessary, however reuse
> pre-owned entries whenever possible.
> Teach the existing VGIC functions to find the right pointer when being
> given a virtual LPI number.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
> xen/arch/arm/gic.c | 3 +++
> xen/arch/arm/vgic-v3.c | 2 ++
> xen/arch/arm/vgic.c | 56
> ++++++++++++++++++++++++++++++++++++++++---
> xen/include/asm-arm/domain.h | 1 +
> xen/include/asm-arm/gic-its.h | 10 ++++++++
> xen/include/asm-arm/vgic.h | 9 +++++++
> 6 files changed, 78 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
> index 63c744a..ebe4035 100644
> --- a/xen/arch/arm/gic.c
> +++ b/xen/arch/arm/gic.c
> @@ -506,6 +506,9 @@ static void gic_update_one_lr(struct vcpu *v, int i)
> struct vcpu *v_target = vgic_get_target_vcpu(v, irq);
> irq_set_affinity(p->desc, cpumask_of(v_target->processor));
> }
> + /* If this was an LPI, mark this struct as available again. */
> + if ( p->irq >= 8192 )
Can define something line is_lpi(irq) and use it everywhere
> + p->irq = 0;
> }
> }
> }
> diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
> index ec038a3..e9b6490 100644
> --- a/xen/arch/arm/vgic-v3.c
> +++ b/xen/arch/arm/vgic-v3.c
> @@ -1388,6 +1388,8 @@ static int vgic_v3_vcpu_init(struct vcpu *v)
> if ( v->vcpu_id == last_cpu || (v->vcpu_id == (d->max_vcpus - 1)) )
> v->arch.vgic.flags |= VGIC_V3_RDIST_LAST;
>
> + INIT_LIST_HEAD(&v->arch.vgic.pending_lpi_list);
> +
> return 0;
> }
>
> diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
> index 0965119..b961551 100644
> --- a/xen/arch/arm/vgic.c
> +++ b/xen/arch/arm/vgic.c
> @@ -31,6 +31,8 @@
> #include <asm/mmio.h>
> #include <asm/gic.h>
> #include <asm/vgic.h>
> +#include <asm/gic_v3_defs.h>
> +#include <asm/gic-its.h>
>
> static inline struct vgic_irq_rank *vgic_get_rank(struct vcpu *v, int rank)
> {
> @@ -61,7 +63,7 @@ struct vgic_irq_rank *vgic_rank_irq(struct vcpu *v,
> unsigned int irq)
> return vgic_get_rank(v, rank);
> }
>
> -static void vgic_init_pending_irq(struct pending_irq *p, unsigned int virq)
> +void vgic_init_pending_irq(struct pending_irq *p, unsigned int virq)
> {
> INIT_LIST_HEAD(&p->inflight);
> INIT_LIST_HEAD(&p->lr_queue);
> @@ -244,10 +246,14 @@ struct vcpu *vgic_get_target_vcpu(struct vcpu *v,
> unsigned int virq)
>
> static int vgic_get_virq_priority(struct vcpu *v, unsigned int virq)
> {
> - struct vgic_irq_rank *rank = vgic_rank_irq(v, virq);
> + struct vgic_irq_rank *rank;
> unsigned long flags;
> int priority;
>
> + if ( virq >= 8192 )
> + return gicv3_lpi_get_priority(v->domain, virq);
> +
> + rank = vgic_rank_irq(v, virq);
> vgic_lock_rank(v, rank, flags);
> priority = rank->priority[virq & INTERRUPT_RANK_MASK];
> vgic_unlock_rank(v, rank, flags);
> @@ -446,13 +452,55 @@ int vgic_to_sgi(struct vcpu *v, register_t sgir, enum
> gic_sgi_mode irqmode, int
> return 1;
> }
>
> +/*
> + * Holding struct pending_irq's for each possible virtual LPI in each domain
> + * requires too much Xen memory, also a malicious guest could potentially
> + * spam Xen with LPI map requests. We cannot cover those with (guest
> allocated)
> + * ITS memory, so we use a dynamic scheme of allocating struct pending_irq's
> + * on demand.
> + */
> +struct pending_irq *lpi_to_pending(struct vcpu *v, unsigned int lpi,
> + bool allocate)
> +{
> + struct lpi_pending_irq *lpi_irq, *empty = NULL;
> +
> + /* TODO: locking! */
> + list_for_each_entry(lpi_irq, &v->arch.vgic.pending_lpi_list, entry)
> + {
> + if ( lpi_irq->pirq.irq == lpi )
> + return &lpi_irq->pirq;
> +
> + if ( lpi_irq->pirq.irq == 0 && !empty )
> + empty = lpi_irq;
> + }
With this approach of allocating pending_irq on demand, if the
pending_lpi_list
is at n position then it iterates for long time to find pending_irq entry.
This will increase LPI injection time to domain.
Why can't we use btree?
> +
> + if ( !allocate )
> + return NULL;
> +
> + if ( !empty )
> + {
> + empty = xzalloc(struct lpi_pending_irq);
> + vgic_init_pending_irq(&empty->pirq, lpi);
> + list_add_tail(&empty->entry, &v->arch.vgic.pending_lpi_list);
> + } else
> + {
> + empty->pirq.status = 0;
> + empty->pirq.irq = lpi;
> + }
> +
> + return &empty->pirq;
> +}
> +
> struct pending_irq *irq_to_pending(struct vcpu *v, unsigned int irq)
> {
> struct pending_irq *n;
> +
> /* Pending irqs allocation strategy: the first vgic.nr_spis irqs
> * are used for SPIs; the rests are used for per cpu irqs */
> if ( irq < 32 )
> n = &v->arch.vgic.pending_irqs[irq];
> + else if ( irq >= 8192 )
> + n = lpi_to_pending(v, irq, true);
> else
> n = &v->domain->arch.vgic.pending_irqs[irq - 32];
> return n;
> @@ -480,7 +528,7 @@ void vgic_clear_pending_irqs(struct vcpu *v)
> void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int virq)
> {
> uint8_t priority;
> - struct pending_irq *iter, *n = irq_to_pending(v, virq);
> + struct pending_irq *iter, *n;
> unsigned long flags;
> bool_t running;
>
> @@ -488,6 +536,8 @@ void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int
> virq)
>
> spin_lock_irqsave(&v->arch.vgic.lock, flags);
>
> + n = irq_to_pending(v, virq);
> +
> /* vcpu offline */
> if ( test_bit(_VPF_down, &v->pause_flags) )
> {
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 9452fcd..ae8a9de 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -249,6 +249,7 @@ struct arch_vcpu
> paddr_t rdist_base;
> #define VGIC_V3_RDIST_LAST (1 << 0) /* last vCPU of the rdist */
> uint8_t flags;
> + struct list_head pending_lpi_list;
> } vgic;
>
> /* Timer registers */
> diff --git a/xen/include/asm-arm/gic-its.h b/xen/include/asm-arm/gic-its.h
> index 4e9841a..1f881c0 100644
> --- a/xen/include/asm-arm/gic-its.h
> +++ b/xen/include/asm-arm/gic-its.h
> @@ -136,6 +136,12 @@ int gicv3_lpi_allocate_host_lpi(struct host_its *its,
> int gicv3_lpi_drop_host_lpi(struct host_its *its,
> uint32_t devid, uint32_t eventid,
> uint32_t host_lpi);
> +
> +static inline int gicv3_lpi_get_priority(struct domain *d, uint32_t lpi)
> +{
> + return GIC_PRI_IRQ;
Why lpi priority is fixed?. can't we use domain set lpi priority?
> +}
> +
> #else
>
> static inline void gicv3_its_dt_init(const struct dt_device_node *node)
> @@ -175,6 +181,10 @@ static inline int gicv3_lpi_drop_host_lpi(struct
> host_its *its,
> {
> return 0;
> }
> +static inline int gicv3_lpi_get_priority(struct domain *d, uint32_t lpi)
> +{
> + return GIC_PRI_IRQ;
> +}
>
> #endif /* CONFIG_HAS_ITS */
>
> diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
> index 300f461..4e29ba6 100644
> --- a/xen/include/asm-arm/vgic.h
> +++ b/xen/include/asm-arm/vgic.h
> @@ -83,6 +83,12 @@ struct pending_irq
> struct list_head lr_queue;
> };
>
> +struct lpi_pending_irq
> +{
> + struct list_head entry;
> + struct pending_irq pirq;
> +};
> +
> #define NR_INTERRUPT_PER_RANK 32
> #define INTERRUPT_RANK_MASK (NR_INTERRUPT_PER_RANK - 1)
>
> @@ -296,8 +302,11 @@ extern struct vcpu *vgic_get_target_vcpu(struct vcpu *v,
> unsigned int virq);
> extern void vgic_vcpu_inject_irq(struct vcpu *v, unsigned int virq);
> extern void vgic_vcpu_inject_spi(struct domain *d, unsigned int virq);
> extern void vgic_clear_pending_irqs(struct vcpu *v);
> +extern void vgic_init_pending_irq(struct pending_irq *p, unsigned int virq);
> extern struct pending_irq *irq_to_pending(struct vcpu *v, unsigned int irq);
> extern struct pending_irq *spi_to_pending(struct domain *d, unsigned int
> irq);
> +extern struct pending_irq *lpi_to_pending(struct vcpu *v, unsigned int irq,
> + bool allocate);
> extern struct vgic_irq_rank *vgic_rank_offset(struct vcpu *v, int b, int n,
> int s);
> extern struct vgic_irq_rank *vgic_rank_irq(struct vcpu *v, unsigned int irq);
> extern int vgic_emulate(struct cpu_user_regs *regs, union hsr hsr);
> --
> 2.9.0
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> https://lists.xen.org/xen-devel
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