| Message ID | 20170609174141.5068-13-andre.przywara@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Andre, On 09/06/17 18:41, Andre Przywara wrote: > The target CPU for an LPI is encoded in the interrupt translation table > entry, so can't be easily derived from just an LPI number (short of > walking *all* tables and find the matching LPI). > To avoid this in case we need to know the VCPU (for the INVALL command, > for instance), put the VCPU ID in the struct pending_irq, so that it is > easily accessible. > We use the remaining 8 bits of padding space for that to avoid enlarging > the size of struct pending_irq. The number of VCPUs is limited to 127 > at the moment anyway, which we also confirm with a BUILD_BUG_ON. > > Signed-off-by: Andre Przywara <andre.przywara@arm.com> Acked-by: Julien Grall <julien.grall@arm.com> Cheers,
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c index 6f88616..546f412 100644 --- a/xen/arch/arm/vgic.c +++ b/xen/arch/arm/vgic.c @@ -62,11 +62,15 @@ struct vgic_irq_rank *vgic_rank_irq(struct vcpu *v, unsigned int irq) void vgic_init_pending_irq(struct pending_irq *p, unsigned int virq) { + /* The lpi_vcpu_id field must be big enough to hold a VCPU ID. */ + BUILD_BUG_ON(BIT(sizeof(p->lpi_vcpu_id) * 8) < MAX_VIRT_CPUS); + memset(p, 0, sizeof(*p)); INIT_LIST_HEAD(&p->inflight); INIT_LIST_HEAD(&p->lr_queue); p->irq = virq; + p->lpi_vcpu_id = INVALID_VCPU_ID; } static void vgic_rank_init(struct vgic_irq_rank *rank, uint8_t index, diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h index d51e277..07b56dc 100644 --- a/xen/include/asm-arm/vgic.h +++ b/xen/include/asm-arm/vgic.h @@ -73,6 +73,7 @@ struct pending_irq uint8_t lr; uint8_t priority; uint8_t lpi_priority; /* Caches the priority if this is an LPI. */ + uint8_t lpi_vcpu_id; /* The VCPU for an LPI. */ /* inflight is used to append instances of pending_irq to * vgic.inflight_irqs */ struct list_head inflight;
The target CPU for an LPI is encoded in the interrupt translation table entry, so can't be easily derived from just an LPI number (short of walking *all* tables and find the matching LPI). To avoid this in case we need to know the VCPU (for the INVALL command, for instance), put the VCPU ID in the struct pending_irq, so that it is easily accessible. We use the remaining 8 bits of padding space for that to avoid enlarging the size of struct pending_irq. The number of VCPUs is limited to 127 at the moment anyway, which we also confirm with a BUILD_BUG_ON. Signed-off-by: Andre Przywara <andre.przywara@arm.com> --- xen/arch/arm/vgic.c | 4 ++++ xen/include/asm-arm/vgic.h | 1 + 2 files changed, 5 insertions(+)