From: Andre Przywara Date: Fri, 15 Jul 2016 11:43:34 +0000 (+0100) Subject: KVM: arm64: vgic-its: Read initial LPI pending table X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=33d3bc9556a7dda5bba2cb6b2d08ae4841ae423e;p=linux-beck.git KVM: arm64: vgic-its: Read initial LPI pending table The LPI pending status for a GICv3 redistributor is held in a table in (guest) memory. To achieve reasonable performance, we cache the pending bit in our struct vgic_irq. The initial pending state must be read from guest memory upon enabling LPIs for this redistributor. As we can't access the guest memory while we hold the lpi_list spinlock, we create a snapshot of the LPI list and iterate over that. Signed-off-by: Andre Przywara Reviewed-by: Marc Zyngier Tested-by: Eric Auger Signed-off-by: Marc Zyngier --- diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c index 14f91ff487cc..2881b84cbf75 100644 --- a/virt/kvm/arm/vgic/vgic-its.c +++ b/virt/kvm/arm/vgic/vgic-its.c @@ -67,6 +67,94 @@ struct its_itte { * supports more. Let's be restrictive here. */ #define CBASER_ADDRESS(x) ((x) & GENMASK_ULL(47, 12)) +#define PENDBASER_ADDRESS(x) ((x) & GENMASK_ULL(47, 16)) + +/* + * Create a snapshot of the current LPI list, so that we can enumerate all + * LPIs without holding any lock. + * Returns the array length and puts the kmalloc'ed array into intid_ptr. + */ +static int vgic_copy_lpi_list(struct kvm *kvm, u32 **intid_ptr) +{ + struct vgic_dist *dist = &kvm->arch.vgic; + struct vgic_irq *irq; + u32 *intids; + int irq_count = dist->lpi_list_count, i = 0; + + /* + * We use the current value of the list length, which may change + * after the kmalloc. We don't care, because the guest shouldn't + * change anything while the command handling is still running, + * and in the worst case we would miss a new IRQ, which one wouldn't + * expect to be covered by this command anyway. + */ + intids = kmalloc_array(irq_count, sizeof(intids[0]), GFP_KERNEL); + if (!intids) + return -ENOMEM; + + spin_lock(&dist->lpi_list_lock); + list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) { + /* We don't need to "get" the IRQ, as we hold the list lock. */ + intids[i] = irq->intid; + if (++i == irq_count) + break; + } + spin_unlock(&dist->lpi_list_lock); + + *intid_ptr = intids; + return irq_count; +} + +/* + * Scan the whole LPI pending table and sync the pending bit in there + * with our own data structures. This relies on the LPI being + * mapped before. + */ +static int its_sync_lpi_pending_table(struct kvm_vcpu *vcpu) +{ + gpa_t pendbase = PENDBASER_ADDRESS(vcpu->arch.vgic_cpu.pendbaser); + struct vgic_irq *irq; + int last_byte_offset = -1; + int ret = 0; + u32 *intids; + int nr_irqs, i; + + nr_irqs = vgic_copy_lpi_list(vcpu->kvm, &intids); + if (nr_irqs < 0) + return nr_irqs; + + for (i = 0; i < nr_irqs; i++) { + int byte_offset, bit_nr; + u8 pendmask; + + byte_offset = intids[i] / BITS_PER_BYTE; + bit_nr = intids[i] % BITS_PER_BYTE; + + /* + * For contiguously allocated LPIs chances are we just read + * this very same byte in the last iteration. Reuse that. + */ + if (byte_offset != last_byte_offset) { + ret = kvm_read_guest(vcpu->kvm, pendbase + byte_offset, + &pendmask, 1); + if (ret) { + kfree(intids); + return ret; + } + last_byte_offset = byte_offset; + } + + irq = vgic_get_irq(vcpu->kvm, NULL, intids[i]); + spin_lock(&irq->irq_lock); + irq->pending = pendmask & (1U << bit_nr); + vgic_queue_irq_unlock(vcpu->kvm, irq); + vgic_put_irq(vcpu->kvm, irq); + } + + kfree(intids); + + return ret; +} static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu, struct vgic_its *its, @@ -403,6 +491,13 @@ static struct vgic_register_region its_registers[] = { VGIC_ACCESS_32bit), }; +/* This is called on setting the LPI enable bit in the redistributor. */ +void vgic_enable_lpis(struct kvm_vcpu *vcpu) +{ + if (!(vcpu->arch.vgic_cpu.pendbaser & GICR_PENDBASER_PTZ)) + its_sync_lpi_pending_table(vcpu); +} + static int vgic_its_init_its(struct kvm *kvm, struct vgic_its *its) { struct vgic_io_device *iodev = &its->iodev; diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h index 8192a293f119..ee348deb8737 100644 --- a/virt/kvm/arm/vgic/vgic.h +++ b/virt/kvm/arm/vgic/vgic.h @@ -25,6 +25,7 @@ #define IS_VGIC_ADDR_UNDEF(_x) ((_x) == VGIC_ADDR_UNDEF) #define INTERRUPT_ID_BITS_SPIS 10 +#define INTERRUPT_ID_BITS_ITS 16 #define VGIC_PRI_BITS 5 #define vgic_irq_is_sgi(intid) ((intid) < VGIC_NR_SGIS) @@ -76,6 +77,7 @@ int vgic_v3_probe(const struct gic_kvm_info *info); int vgic_v3_map_resources(struct kvm *kvm); int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t dist_base_address); bool vgic_has_its(struct kvm *kvm); +void vgic_enable_lpis(struct kvm_vcpu *vcpu); #else static inline void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu) { @@ -133,6 +135,9 @@ static inline bool vgic_has_its(struct kvm *kvm) return false; } +static inline void vgic_enable_lpis(struct kvm_vcpu *vcpu) +{ +} #endif int kvm_register_vgic_device(unsigned long type);