[RFC PATCH 09/45] KVM: arm/arm64: vgic-new: Add GICv2 IRQ sync/flush

[Andre Przywara <andre.przywara@arm.com>]

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

Implement the functionality for syncing IRQs between our emulation
and the list registers, which represent the guest's view of IRQs.
This is done in kvm_vgic_flush_hwstate and kvm_vgic_sync_hwstate,
which gets called on guest entry and exit.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Eric Auger <eric.auger@linaro.org>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 include/kvm/vgic/vgic.h     |   4 +
 virt/kvm/arm/vgic/vgic-v2.c | 161 ++++++++++++++++++++++++++++++++++
 virt/kvm/arm/vgic/vgic.c    | 204 ++++++++++++++++++++++++++++++++++++++++++++
 virt/kvm/arm/vgic/vgic.h    |   4 +
 4 files changed, 373 insertions(+)

diff --git a/include/kvm/vgic/vgic.h b/include/kvm/vgic/vgic.h
index f32b284..986f23f 100644
--- a/include/kvm/vgic/vgic.h
+++ b/include/kvm/vgic/vgic.h
@@ -187,6 +187,10 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 #define vgic_valid_spi(k,i)	(((i) >= VGIC_NR_PRIVATE_IRQS) && \
 			((i) < (k)->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS))
 
+bool kvm_vcpu_has_pending_irqs(struct kvm_vcpu *vcpu);
+void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu);
+void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu);
+
 /**
  * kvm_vgic_get_max_vcpus - Get the maximum number of VCPUs allowed by HW
  *
diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
index 0bf6f27..1cec423 100644
--- a/virt/kvm/arm/vgic/vgic-v2.c
+++ b/virt/kvm/arm/vgic/vgic-v2.c
@@ -14,11 +14,172 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/irqchip/arm-gic.h>
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
 
 #include "vgic.h"
 
+/*
+ * Call this function to convert a u64 value to an unsigned long * bitmask
+ * in a way that works on both 32-bit and 64-bit LE and BE platforms.
+ *
+ * Warning: Calling this function may modify *val.
+ */
+static unsigned long *u64_to_bitmask(u64 *val)
+{
+#if defined(CONFIG_CPU_BIG_ENDIAN) && BITS_PER_LONG == 32
+	*val = (*val >> 32) | (*val << 32);
+#endif
+	return (unsigned long *)val;
+}
+
+void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;
+
+	if (cpuif->vgic_misr & GICH_MISR_EOI) {
+		u64 eisr = cpuif->vgic_eisr;
+		unsigned long *eisr_bmap = u64_to_bitmask(&eisr);
+		int lr;
+
+		for_each_set_bit(lr, eisr_bmap, vcpu->arch.vgic_cpu.nr_lr) {
+			struct vgic_irq *irq;
+			u32 intid = cpuif->vgic_lr[lr] & GICH_LR_VIRTUALID;
+
+			irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
+
+			WARN_ON(irq->config == VGIC_CONFIG_EDGE);
+			WARN_ON(cpuif->vgic_lr[lr] & GICH_LR_STATE);
+
+			kvm_notify_acked_irq(vcpu->kvm, 0,
+					     intid - VGIC_NR_PRIVATE_IRQS);
+
+			cpuif->vgic_lr[lr] &= ~GICH_LR_STATE; /* Useful?? */
+			cpuif->vgic_elrsr |= 1ULL << lr;
+		}
+	}
+
+	/* check and disable underflow maintenance IRQ */
+	cpuif->vgic_hcr &= ~GICH_HCR_UIE;
+
+	/*
+	 * In the next iterations of the vcpu loop, if we sync the
+	 * vgic state after flushing it, but before entering the guest
+	 * (this happens for pending signals and vmid rollovers), then
+	 * make sure we don't pick up any old maintenance interrupts
+	 * here.
+	 */
+	cpuif->vgic_eisr = 0;
+}
+
+void vgic_v2_set_underflow(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;
+
+	cpuif->vgic_hcr |= GICH_HCR_UIE;
+}
+
+/*
+ * transfer the content of the LRs back into the corresponding ap_list:
+ * - active bit is transferred as is
+ * - pending bit is
+ *   - transferred as is in case of edge sensitive IRQs
+ *   - set to the line-level (resample time) for level sensitive IRQs
+ */
+void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;
+	int lr;
+
+	for (lr = 0; lr < vcpu->arch.vgic_cpu.used_lrs; lr++) {
+		u32 val = cpuif->vgic_lr[lr];
+		u32 intid = val & GICH_LR_VIRTUALID;
+		struct vgic_irq *irq;
+
+		irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
+
+		spin_lock(&irq->irq_lock);
+
+		/* Always preserve the active bit */
+		irq->active = !!(val & GICH_LR_ACTIVE_BIT);
+
+		/* Edge is the only case where we preserve the pending bit */
+		if (irq->config == VGIC_CONFIG_EDGE &&
+		    (val & GICH_LR_PENDING_BIT)) {
+			irq->pending = true;
+
+			if (intid < VGIC_NR_SGIS) {
+				u32 cpuid = val & GICH_LR_PHYSID_CPUID;
+
+				cpuid >>= GICH_LR_PHYSID_CPUID_SHIFT;
+				irq->source |= (1 << cpuid);
+			}
+		}
+
+		/* Clear soft pending state when level IRQs have been acked */
+		if (irq->config == VGIC_CONFIG_LEVEL &&
+		    !(val & GICH_LR_PENDING_BIT)) {
+			irq->soft_pending = false;
+			irq->pending = irq->line_level;
+		}
+
+		spin_unlock(&irq->irq_lock);
+	}
+}
+
+/*
+ * Populates the particular LR with the state of a given IRQ:
+ * - for an edge sensitive IRQ the pending state is reset in the struct
+ * - for a level sensitive IRQ the pending state value is unchanged;
+ *   it will be resampled on deactivation
+ *
+ * If irq is not NULL, the irq_lock must be hold already by the caller.
+ * If irq is NULL, the respective LR gets cleared.
+ */
+void vgic_v2_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
+{
+	u32 val;
+
+	if (!irq) {
+		val = 0;
+		goto out;
+	}
+
+	val = irq->intid;
+
+	if (irq->pending) {
+		val |= GICH_LR_PENDING_BIT;
+
+		if (irq->config == VGIC_CONFIG_EDGE)
+			irq->pending = false;
+
+		if (irq->intid < VGIC_NR_SGIS) {
+			u32 src = ffs(irq->source);
+
+			BUG_ON(!src);
+			val |= (src - 1) << GICH_LR_PHYSID_CPUID_SHIFT;
+			irq->source &= ~(1 << (src - 1));
+			if (irq->source)
+				irq->pending = true;
+		}
+	}
+
+	if (irq->active)
+		val |= GICH_LR_ACTIVE_BIT;
+
+	if (irq->hw) {
+		val |= GICH_LR_HW;
+		val |= irq->hwintid << GICH_LR_PHYSID_CPUID_SHIFT;
+	} else {
+		if (irq->config == VGIC_CONFIG_LEVEL)
+			val |= GICH_LR_EOI;
+	}
+
+out:
+	vcpu->arch.vgic_cpu.vgic_v2.vgic_lr[lr] = val;
+}
+
 void vgic_v2_irq_change_affinity(struct kvm *kvm, u32 intid, u8 new_targets)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 29c753e..90a85bf 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -273,3 +273,207 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 	vgic_update_irq_pending(kvm, vcpu, intid, level);
 	return 0;
 }
+
+/**
+ * vgic_prune_ap_list - Remove non-relevant interrupts from the list
+ *
+ * @vcpu: The VCPU pointer
+ *
+ * Go over the list of "interesting" interrupts, and prune those that we
+ * won't have to consider in the near future.
+ */
+static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
+{
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	struct vgic_irq *irq, *tmp;
+
+retry:
+	spin_lock(&vgic_cpu->ap_list_lock);
+
+	list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
+		struct kvm_vcpu *target_vcpu, *vcpuA, *vcpuB;
+
+		spin_lock(&irq->irq_lock);
+
+		BUG_ON(vcpu != irq->vcpu);
+
+		target_vcpu = vgic_target_oracle(irq);
+
+		if (!target_vcpu) {
+			/*
+			 * We don't need to process this interrupt any
+			 * further, move it off the list.
+			 */
+			list_del_init(&irq->ap_list);
+			irq->vcpu = NULL;
+			spin_unlock(&irq->irq_lock);
+			continue;
+		}
+
+		if (target_vcpu == vcpu) {
+			/* We're on the right CPU */
+			spin_unlock(&irq->irq_lock);
+			continue;
+		}
+
+		/* This interrupt looks like it has to be migrated. */
+
+		spin_unlock(&irq->irq_lock);
+		spin_unlock(&vgic_cpu->ap_list_lock);
+
+		/*
+		 * Ensure locking order by always locking the smallest
+		 * ID first.
+		 */
+		if (vcpu->vcpu_id < target_vcpu->vcpu_id) {
+			vcpuA = vcpu;
+			vcpuB = target_vcpu;
+		} else {
+			vcpuA = target_vcpu;
+			vcpuB = vcpu;
+		}
+
+		spin_lock(&vcpuA->arch.vgic_cpu.ap_list_lock);
+		spin_lock(&vcpuB->arch.vgic_cpu.ap_list_lock);
+		spin_lock(&irq->irq_lock);
+
+		/*
+		 * If the affinity has been preserved, move the
+		 * interrupt around. Otherwise, it means things have
+		 * changed while the interrupt was unlocked, and we
+		 * need to replay this.
+		 *
+		 * In all cases, we cannot trust the list not to have
+		 * changed, so we restart from the beginning.
+		 */
+		if (target_vcpu == vgic_target_oracle(irq)) {
+			struct vgic_cpu *new_cpu = &target_vcpu->arch.vgic_cpu;
+
+			list_del_init(&irq->ap_list);
+			irq->vcpu = target_vcpu;
+			list_add_tail(&irq->ap_list, &new_cpu->ap_list_head);
+		}
+
+		spin_unlock(&irq->irq_lock);
+		spin_unlock(&vcpuB->arch.vgic_cpu.ap_list_lock);
+		spin_unlock(&vcpuA->arch.vgic_cpu.ap_list_lock);
+		goto retry;
+	}
+
+	spin_unlock(&vgic_cpu->ap_list_lock);
+}
+
+static inline void vgic_process_maintenance_interrupt(struct kvm_vcpu *vcpu)
+{
+	if (kvm_vgic_global_state.type == VGIC_V2)
+		vgic_v2_process_maintenance(vcpu);
+	else
+		WARN(1, "GICv3 Not Implemented\n");
+}
+
+static inline void vgic_fold_lr_state(struct kvm_vcpu *vcpu)
+{
+	if (kvm_vgic_global_state.type == VGIC_V2)
+		vgic_v2_fold_lr_state(vcpu);
+	else
+		WARN(1, "GICv3 Not Implemented\n");
+}
+
+/*
+ * Requires the ap_lock to be held.
+ * If irq is not NULL, requires the IRQ lock to be held as well.
+ * If irq is NULL, the list register gets cleared.
+ */
+static inline void vgic_populate_lr(struct kvm_vcpu *vcpu,
+				    struct vgic_irq *irq, int lr)
+{
+	if (kvm_vgic_global_state.type == VGIC_V2)
+		vgic_v2_populate_lr(vcpu, irq, lr);
+	else
+		WARN(1, "GICv3 Not Implemented\n");
+}
+
+static inline void vgic_set_underflow(struct kvm_vcpu *vcpu)
+{
+	if (kvm_vgic_global_state.type == VGIC_V2)
+		vgic_v2_set_underflow(vcpu);
+	else
+		WARN(1, "GICv3 Not Implemented\n");
+}
+
+static int compute_ap_list_depth(struct kvm_vcpu *vcpu)
+{
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	struct vgic_irq *irq;
+	int count = 0;
+
+	list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
+		spin_lock(&irq->irq_lock);
+		/* GICv2 SGIs can count for more than one... */
+		if (irq->intid < VGIC_NR_SGIS && irq->source)
+			count += hweight8(irq->source);
+		else
+			count++;
+		spin_unlock(&irq->irq_lock);
+	}
+	return count;
+}
+
+/* requires the vcpu ap_lock to be held */
+static void vgic_populate_lrs(struct kvm_vcpu *vcpu)
+{
+	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+	u32 model = vcpu->kvm->arch.vgic.vgic_model;
+	struct vgic_irq *irq;
+	int count = 0;
+
+	if (compute_ap_list_depth(vcpu) > vcpu->arch.vgic_cpu.nr_lr) {
+		vgic_set_underflow(vcpu);
+		vgic_sort_ap_list(vcpu);
+	}
+
+	list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
+		spin_lock(&irq->irq_lock);
+
+		if (unlikely(vgic_target_oracle(irq) != vcpu))
+			goto next;
+
+		/*
+		 * If we get an SGI with multiple sources, try to get
+		 * them in all at once.
+		 */
+		if (model == KVM_DEV_TYPE_ARM_VGIC_V2 &&
+		    irq->intid < VGIC_NR_SGIS) {
+			while (irq->source && count < vcpu->arch.vgic_cpu.nr_lr)
+				vgic_populate_lr(vcpu, irq, count++);
+		} else {
+			vgic_populate_lr(vcpu, irq, count++);
+		}
+
+next:
+		spin_unlock(&irq->irq_lock);
+
+		if (count == vcpu->arch.vgic_cpu.nr_lr)
+			break;
+	}
+
+	vcpu->arch.vgic_cpu.used_lrs = count;
+
+	/* Nuke remaining LRs */
+	for ( ; count < vcpu->arch.vgic_cpu.nr_lr; count++)
+		vgic_populate_lr(vcpu, NULL, count);
+}
+
+void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
+{
+	vgic_process_maintenance_interrupt(vcpu);
+	vgic_fold_lr_state(vcpu);
+	vgic_prune_ap_list(vcpu);
+}
+
+void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
+{
+	spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
+	vgic_populate_lrs(vcpu);
+	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
+}
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index b2faf00..95ef3cf 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -21,5 +21,9 @@ struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
 bool vgic_queue_irq(struct kvm *kvm, struct vgic_irq *irq);
 
 void vgic_v2_irq_change_affinity(struct kvm *kvm, u32 intid, u8 target);
+void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu);
+void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu);
+void vgic_v2_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr);
+void vgic_v2_set_underflow(struct kvm_vcpu *vcpu);
 
 #endif
-- 
2.7.3