[PATCH v4 4/6] KVM: arm64: GICv4.1: Try to save VLPI state in save_pending_tables

[Shenming Lu <lushenming@huawei.com>]

After pausing all vCPUs and devices capable of interrupting, in order
to save the states of all interrupts, besides flushing the states in
kvm’s vgic, we also try to flush the states of VLPIs in the virtual
pending tables into guest RAM, but we need to have GICv4.1 and safely
unmap the vPEs first.

As for the saving of VSGIs, which needs the vPEs to be mapped and might
conflict with the saving of VLPIs, but since we will map the vPEs back
at the end of save_pending_tables and both savings require the kvm->lock
to be held (thus only happen serially), it will work fine.

Signed-off-by: Shenming Lu <lushenming@huawei.com>
---
 arch/arm64/kvm/vgic/vgic-v3.c | 66 +++++++++++++++++++++++++++++++----
 1 file changed, 60 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
index 52915b342351..359d4dc35264 100644
--- a/arch/arm64/kvm/vgic/vgic-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-v3.c
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
 #include <linux/irqchip/arm-gic-v3.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
 #include <kvm/arm_vgic.h>
@@ -356,6 +358,32 @@ int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq)
 	return 0;
 }
 
+/*
+ * The deactivation of the doorbell interrupt will trigger the
+ * unmapping of the associated vPE.
+ */
+static void unmap_all_vpes(struct vgic_dist *dist)
+{
+	struct irq_desc *desc;
+	int i;
+
+	for (i = 0; i < dist->its_vm.nr_vpes; i++) {
+		desc = irq_to_desc(dist->its_vm.vpes[i]->irq);
+		irq_domain_deactivate_irq(irq_desc_get_irq_data(desc));
+	}
+}
+
+static void map_all_vpes(struct vgic_dist *dist)
+{
+	struct irq_desc *desc;
+	int i;
+
+	for (i = 0; i < dist->its_vm.nr_vpes; i++) {
+		desc = irq_to_desc(dist->its_vm.vpes[i]->irq);
+		irq_domain_activate_irq(irq_desc_get_irq_data(desc), false);
+	}
+}
+
 /**
  * vgic_v3_save_pending_tables - Save the pending tables into guest RAM
  * kvm lock and all vcpu lock must be held
@@ -365,13 +393,28 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
 	struct vgic_dist *dist = &kvm->arch.vgic;
 	struct vgic_irq *irq;
 	gpa_t last_ptr = ~(gpa_t)0;
-	int ret;
+	bool vlpi_avail = false;
+	int ret = 0;
 	u8 val;
 
+	if (unlikely(!vgic_initialized(kvm)))
+		return -ENXIO;
+
+	/*
+	 * A preparation for getting any VLPI states.
+	 * The above vgic initialized check also ensures that the allocation
+	 * and enabling of the doorbells have already been done.
+	 */
+	if (kvm_vgic_global_state.has_gicv4_1) {
+		unmap_all_vpes(dist);
+		vlpi_avail = true;
+	}
+
 	list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
 		int byte_offset, bit_nr;
 		struct kvm_vcpu *vcpu;
 		gpa_t pendbase, ptr;
+		bool is_pending;
 		bool stored;
 
 		vcpu = irq->target_vcpu;
@@ -387,24 +430,35 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
 		if (ptr != last_ptr) {
 			ret = kvm_read_guest_lock(kvm, ptr, &val, 1);
 			if (ret)
-				return ret;
+				goto out;
 			last_ptr = ptr;
 		}
 
 		stored = val & (1U << bit_nr);
-		if (stored == irq->pending_latch)
+
+		is_pending = irq->pending_latch;
+
+		if (irq->hw && vlpi_avail)
+			vgic_v4_get_vlpi_state(irq, &is_pending);
+
+		if (stored == is_pending)
 			continue;
 
-		if (irq->pending_latch)
+		if (is_pending)
 			val |= 1 << bit_nr;
 		else
 			val &= ~(1 << bit_nr);
 
 		ret = kvm_write_guest_lock(kvm, ptr, &val, 1);
 		if (ret)
-			return ret;
+			goto out;
 	}
-	return 0;
+
+out:
+	if (vlpi_avail)
+		map_all_vpes(dist);
+
+	return ret;
 }
 
 /**
-- 
2.19.1