[PATCH v5 07/12] ARM: KVM: VGIC virtual CPU interface management

Christoffer Dall
2013-01-08T18:42:13Z

From: Marc Zyngier <marc.zyngier@arm.com>

Add VGIC virtual CPU interface code, picking pending interrupts
from the distributor and stashing them in the VGIC control interface
list registers.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>
---
arch/arm/include/asm/kvm_vgic.h | 30 ++++
arch/arm/kvm/vgic.c | 327 +++++++++++++++++++++++++++++++++++++++
2 files changed, 356 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/kvm_vgic.h b/arch/arm/include/asm/kvm_vgic.h
index 9ff0d9c..b3133c4 100644
--- a/arch/arm/include/asm/kvm_vgic.h
+++ b/arch/arm/include/asm/kvm_vgic.h
@@ -110,8 +110,33 @@ struct vgic_dist {
};

struct vgic_cpu {
+#ifdef CONFIG_KVM_ARM_VGIC
+ /* per IRQ to LR mapping */
+ u8 vgic_irq_lr_map[VGIC_NR_IRQS];
+
+ /* Pending interrupts on this VCPU */
+ DECLARE_BITMAP( pending_percpu, VGIC_NR_PRIVATE_IRQS);
+ DECLARE_BITMAP( pending_shared, VGIC_NR_SHARED_IRQS);
+
+ /* Bitmap of used/free list registers */
+ DECLARE_BITMAP( lr_used, 64);
+
+ /* Number of list registers on this CPU */
+ int nr_lr;
+
+ /* CPU vif control registers for world switch */
+ u32 vgic_hcr;
+ u32 vgic_vmcr;
+ u32 vgic_misr; /* Saved only */
+ u32 vgic_eisr[2]; /* Saved only */
+ u32 vgic_elrsr[2]; /* Saved only */
+ u32 vgic_apr;
+ u32 vgic_lr[64]; /* A15 has only 4... */
+#endif
};

+#define LR_EMPTY 0xff
+
struct kvm;
struct kvm_vcpu;
struct kvm_run;
@@ -119,9 +144,14 @@ struct kvm_exit_mmio;

#ifdef CONFIG_KVM_ARM_VGIC
int kvm_vgic_set_addr(struct kvm *kvm, unsigned long type, u64 addr);
+void kvm_vgic_sync_to_cpu(struct kvm_vcpu *vcpu);
+void kvm_vgic_sync_from_cpu(struct kvm_vcpu *vcpu);
+int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
struct kvm_exit_mmio *mmio);

+#define irqchip_in_kernel(k) (!!((k)->arch.vgic.vctrl_base))
+
#else
static inline int kvm_vgic_hyp_init(void)
{
diff --git a/arch/arm/kvm/vgic.c b/arch/arm/kvm/vgic.c
index bd2bd7f..58237d5 100644
--- a/arch/arm/kvm/vgic.c
+++ b/arch/arm/kvm/vgic.c
@@ -152,6 +152,34 @@ static int vgic_irq_is_enabled(struct kvm_vcpu *vcpu, int irq)
return vgic_bitmap_get_irq_val(&dist->irq_enabled, vcpu->vcpu_id, irq);
}

+static int vgic_irq_is_active(struct kvm_vcpu *vcpu, int irq)
+{
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+ return vgic_bitmap_get_irq_val(&dist->irq_active, vcpu->vcpu_id, irq);
+}
+
+static void vgic_irq_set_active(struct kvm_vcpu *vcpu, int irq)
+{
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+ vgic_bitmap_set_irq_val(&dist->irq_active, vcpu->vcpu_id, irq, 1);
+}
+
+static void vgic_irq_clear_active(struct kvm_vcpu *vcpu, int irq)
+{
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+ vgic_bitmap_set_irq_val(&dist->irq_active, vcpu->vcpu_id, irq, 0);
+}
+
+static int vgic_dist_irq_is_pending(struct kvm_vcpu *vcpu, int irq)
+{
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+ return vgic_bitmap_get_irq_val(&dist->irq_state, vcpu->vcpu_id, irq);
+}
+
static void vgic_dist_irq_set(struct kvm_vcpu *vcpu, int irq)
{
struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
@@ -711,7 +739,30 @@ static void vgic_dispatch_sgi(struct kvm_vcpu *vcpu, u32 reg)

static int compute_pending_for_cpu(struct kvm_vcpu *vcpu)
{
- return 0;
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+ unsigned long *pending, *enabled, *pend_percpu, *pend_shared;
+ unsigned long pending_private, pending_shared;
+ int vcpu_id;
+
+ vcpu_id = vcpu->vcpu_id;
+ pend_percpu = vcpu->arch.vgic_cpu.pending_percpu;
+ pend_shared = vcpu->arch.vgic_cpu.pending_shared;
+
+ pending = vgic_bitmap_get_cpu_map(&dist->irq_state, vcpu_id);
+ enabled = vgic_bitmap_get_cpu_map(&dist->irq_enabled, vcpu_id);
+ bitmap_and(pend_percpu, pending, enabled, VGIC_NR_PRIVATE_IRQS);
+
+ pending = vgic_bitmap_get_shared_map(&dist->irq_state);
+ enabled = vgic_bitmap_get_shared_map(&dist->irq_enabled);
+ bitmap_and(pend_shared, pending, enabled, VGIC_NR_SHARED_IRQS);
+ bitmap_and(pend_shared, pend_shared,
+ vgic_bitmap_get_shared_map(&dist->irq_spi_target[vcpu_id]),
+ VGIC_NR_SHARED_IRQS);
+
+ pending_private = find_first_bit(pend_percpu, VGIC_NR_PRIVATE_IRQS);
+ pending_shared = find_first_bit(pend_shared, VGIC_NR_SHARED_IRQS);
+ return (pending_private < VGIC_NR_PRIVATE_IRQS ||
+ pending_shared < VGIC_NR_SHARED_IRQS);
}

/*
@@ -737,6 +788,280 @@ static void vgic_update_state(struct kvm *kvm)
}
}

+#define LR_CPUID(lr) \
+ (((lr) & GICH_LR_PHYSID_CPUID) >> GICH_LR_PHYSID_CPUID_SHIFT)
+#define MK_LR_PEND(src, irq) \
+ (GICH_LR_PENDING_BIT | ((src) << GICH_LR_PHYSID_CPUID_SHIFT) | (irq))
+/*
+ * Queue an interrupt to a CPU virtual interface. Return true on success,
+ * or false if it wasn't possible to queue it.
+ */
+static bool vgic_queue_irq(struct kvm_vcpu *vcpu, u8 sgi_source_id, int irq)
+{
+ struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+ int lr;
+
+ /* Sanitize the input... */
+ BUG_ON(sgi_source_id & ~7);
+ BUG_ON(sgi_source_id && irq > 15);
+ BUG_ON(irq >= VGIC_NR_IRQS);
+
+ kvm_debug("Queue IRQ%d\n", irq);
+
+ lr = vgic_cpu->vgic_irq_lr_map[irq];
+
+ /* Do we have an active interrupt for the same CPUID? */
+ if (lr != LR_EMPTY &&
+ (LR_CPUID(vgic_cpu->vgic_lr[lr]) == sgi_source_id)) {
+ kvm_debug("LR%d piggyback for IRQ%d %x\n",
+ lr, irq, vgic_cpu->vgic_lr[lr]);
+ BUG_ON(!test_bit(lr, vgic_cpu->lr_used));
+ vgic_cpu->vgic_lr[lr] |= GICH_LR_PENDING_BIT;
+
+ goto out;
+ }
+
+ /* Try to use another LR for this interrupt */
+ lr = find_first_zero_bit((unsigned long *)vgic_cpu->lr_used,
+ vgic_cpu->nr_lr);
+ if (lr >= vgic_cpu->nr_lr)
+ return false;
+
+ kvm_debug("LR%d allocated for IRQ%d %x\n", lr, irq, sgi_source_id);
+ vgic_cpu->vgic_lr[lr] = MK_LR_PEND(sgi_source_id, irq);
+ vgic_cpu->vgic_irq_lr_map[irq] = lr;
+ set_bit(lr, vgic_cpu->lr_used);
+
+out:
+ if (!vgic_irq_is_edge(vcpu, irq))
+ vgic_cpu->vgic_lr[lr] |= GICH_LR_EOI;
+
+ return true;
+}
+
+static bool vgic_queue_sgi(struct kvm_vcpu *vcpu, int irq)
+{
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+ unsigned long sources;
+ int vcpu_id = vcpu->vcpu_id;
+ int c;
+
+ sources = dist->irq_sgi_sources[vcpu_id][irq];
+
+ for_each_set_bit(c, &sources, VGIC_MAX_CPUS) {
+ if (vgic_queue_irq(vcpu, c, irq))
+ clear_bit(c, &sources);
+ }
+
+ dist->irq_sgi_sources[vcpu_id][irq] = sources;
+
+ /*
+ * If the sources bitmap has been cleared it means that we
+ * could queue all the SGIs onto link registers (see the
+ * clear_bit above), and therefore we are done with them in
+ * our emulated gic and can get rid of them.
+ */
+ if (!sources) {
+ vgic_dist_irq_clear(vcpu, irq);
+ vgic_cpu_irq_clear(vcpu, irq);
+ return true;
+ }
+
+ return false;
+}
+
+static bool vgic_queue_hwirq(struct kvm_vcpu *vcpu, int irq)
+{
+ if (vgic_irq_is_active(vcpu, irq))
+ return true; /* level interrupt, already queued */
+
+ if (vgic_queue_irq(vcpu, 0, irq)) {
+ if (vgic_irq_is_edge(vcpu, irq)) {
+ vgic_dist_irq_clear(vcpu, irq);
+ vgic_cpu_irq_clear(vcpu, irq);
+ } else {
+ vgic_irq_set_active(vcpu, irq);
+ }
+
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Fill the list registers with pending interrupts before running the
+ * guest.
+ */
+static void __kvm_vgic_sync_to_cpu(struct kvm_vcpu *vcpu)
+{
+ struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+ int i, vcpu_id;
+ int overflow = 0;
+
+ vcpu_id = vcpu->vcpu_id;
+
+ /*
+ * We may not have any pending interrupt, or the interrupts
+ * may have been serviced from another vcpu. In all cases,
+ * move along.
+ */
+ if (!kvm_vgic_vcpu_pending_irq(vcpu)) {
+ pr_debug("CPU%d has no pending interrupt\n", vcpu_id);
+ goto epilog;
+ }
+
+ /* SGIs */
+ for_each_set_bit(i, vgic_cpu->pending_percpu, VGIC_NR_SGIS) {
+ if (!vgic_queue_sgi(vcpu, i))
+ overflow = 1;
+ }
+
+ /* PPIs */
+ for_each_set_bit_from(i, vgic_cpu->pending_percpu, VGIC_NR_PRIVATE_IRQS) {
+ if (!vgic_queue_hwirq(vcpu, i))
+ overflow = 1;
+ }
+
+ /* SPIs */
+ for_each_set_bit(i, vgic_cpu->pending_shared, VGIC_NR_SHARED_IRQS) {
+ if (!vgic_queue_hwirq(vcpu, i + VGIC_NR_PRIVATE_IRQS))
+ overflow = 1;
+ }
+
+epilog:
+ if (overflow) {
+ vgic_cpu->vgic_hcr |= GICH_HCR_UIE;
+ } else {
+ vgic_cpu->vgic_hcr &= ~GICH_HCR_UIE;
+ /*
+ * We're about to run this VCPU, and we've consumed
+ * everything the distributor had in store for
+ * us. Claim we don't have anything pending. We'll
+ * adjust that if needed while exiting.
+ */
+ clear_bit(vcpu_id, &dist->irq_pending_on_cpu);
+ }
+}
+
+static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
+{
+ struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+ bool level_pending = false;
+
+ kvm_debug("MISR = %08x\n", vgic_cpu->vgic_misr);
+
+ /*
+ * We do not need to take the distributor lock here, since the only
+ * action we perform is clearing the irq_active_bit for an EOIed
+ * level interrupt. There is a potential race with
+ * the queuing of an interrupt in __kvm_sync_to_cpu(), where we check
+ * if the interrupt is already active. Two possibilities:
+ *
+ * - The queuing is occurring on the same vcpu: cannot happen,
+ * as we're already in the context of this vcpu, and
+ * executing the handler
+ * - The interrupt has been migrated to another vcpu, and we
+ * ignore this interrupt for this run. Big deal. It is still
+ * pending though, and will get considered when this vcpu
+ * exits.
+ */
+ if (vgic_cpu->vgic_misr & GICH_MISR_EOI) {
+ /*
+ * Some level interrupts have been EOIed. Clear their
+ * active bit.
+ */
+ int lr, irq;
+
+ for_each_set_bit(lr, (unsigned long *)vgic_cpu->vgic_eisr,
+ vgic_cpu->nr_lr) {
+ irq = vgic_cpu->vgic_lr[lr] & GICH_LR_VIRTUALID;
+
+ vgic_irq_clear_active(vcpu, irq);
+ vgic_cpu->vgic_lr[lr] &= ~GICH_LR_EOI;
+
+ /* Any additional pending interrupt? */
+ if (vgic_dist_irq_is_pending(vcpu, irq)) {
+ vgic_cpu_irq_set(vcpu, irq);
+ level_pending = true;
+ } else {
+ vgic_cpu_irq_clear(vcpu, irq);
+ }
+ }
+ }
+
+ if (vgic_cpu->vgic_misr & GICH_MISR_U)
+ vgic_cpu->vgic_hcr &= ~GICH_HCR_UIE;
+
+ return level_pending;
+}
+
+/*
+ * Sync back the VGIC state after a guest run. We do not really touch
+ * the distributor here (the irq_pending_on_cpu bit is safe to set),
+ * so there is no need for taking its lock.
+ */
+static void __kvm_vgic_sync_from_cpu(struct kvm_vcpu *vcpu)
+{
+ struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+ int lr, pending;
+ bool level_pending;
+
+ level_pending = vgic_process_maintenance(vcpu);
+
+ /* Clear mappings for empty LRs */
+ for_each_set_bit(lr, (unsigned long *)vgic_cpu->vgic_elrsr,
+ vgic_cpu->nr_lr) {
+ int irq;
+
+ if (!test_and_clear_bit(lr, vgic_cpu->lr_used))
+ continue;
+
+ irq = vgic_cpu->vgic_lr[lr] & GICH_LR_VIRTUALID;
+
+ BUG_ON(irq >= VGIC_NR_IRQS);
+ vgic_cpu->vgic_irq_lr_map[irq] = LR_EMPTY;
+ }
+
+ /* Check if we still have something up our sleeve... */
+ pending = find_first_zero_bit((unsigned long *)vgic_cpu->vgic_elrsr,
+ vgic_cpu->nr_lr);
+ if (level_pending || pending < vgic_cpu->nr_lr)
+ set_bit(vcpu->vcpu_id, &dist->irq_pending_on_cpu);
+}
+
+void kvm_vgic_sync_to_cpu(struct kvm_vcpu *vcpu)
+{
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+ if (!irqchip_in_kernel(vcpu->kvm))
+ return;
+
+ spin_lock(&dist->lock);
+ __kvm_vgic_sync_to_cpu(vcpu);
+ spin_unlock(&dist->lock);
+}
+
+void kvm_vgic_sync_from_cpu(struct kvm_vcpu *vcpu)
+{
+ if (!irqchip_in_kernel(vcpu->kvm))
+ return;
+
+ __kvm_vgic_sync_from_cpu(vcpu);
+}
+
+int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
+{
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
+ if (!irqchip_in_kernel(vcpu->kvm))
+ return 0;
+
+ return test_bit(vcpu->vcpu_id, &dist->irq_pending_on_cpu);
+}
+
static bool vgic_ioaddr_overlap(struct kvm *kvm)
{
phys_addr_t dist = kvm->arch.vgic.vgic_dist_base;