KVM: arm/arm64: vgic: Use a single IO device per redistributor

At the moment we use 2 IO devices per GICv3 redistributor: one
one for the RD_base frame and one for the SGI_base frame.

Instead we can use a single IO device per redistributor (the 2
frames are contiguous). This saves slots on the KVM_MMIO_BUS
which is currently limited to NR_IOBUS_DEVS (1000).

This change allows to instantiate up to 512 redistributors and may
speed the guest boot with a large number of VCPUs.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

2 files changed, 24 insertions, 58 deletions

diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 9175bfd83263..958e2f0d2207 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -193,7 +193,6 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
         int i;
 
         vgic_cpu->rd_iodev.base_addr = VGIC_ADDR_UNDEF;
-        vgic_cpu->sgi_iodev.base_addr = VGIC_ADDR_UNDEF;
 
         INIT_LIST_HEAD(&vgic_cpu->ap_list_head);
         raw_spin_lock_init(&vgic_cpu->ap_list_lock);
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
index fdcfb7ae4491..7dfd15dbb308 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
@@ -517,7 +517,8 @@ static const struct vgic_register_region vgic_v3_dist_registers[] = {
                 VGIC_ACCESS_32bit),
 };
 
-static const struct vgic_register_region vgic_v3_rdbase_registers[] = {
+static const struct vgic_register_region vgic_v3_rd_registers[] = {
+        /* RD_base registers */
         REGISTER_DESC_WITH_LENGTH(GICR_CTLR,
                 vgic_mmio_read_v3r_ctlr, vgic_mmio_write_v3r_ctlr, 4,
                 VGIC_ACCESS_32bit),
@@ -542,44 +543,42 @@ static const struct vgic_register_region vgic_v3_rdbase_registers[] = {
         REGISTER_DESC_WITH_LENGTH(GICR_IDREGS,
                 vgic_mmio_read_v3_idregs, vgic_mmio_write_wi, 48,
                 VGIC_ACCESS_32bit),
-};
-
-static const struct vgic_register_region vgic_v3_sgibase_registers[] = {
-        REGISTER_DESC_WITH_LENGTH(GICR_IGROUPR0,
+        /* SGI_base registers */
+        REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_IGROUPR0,
                 vgic_mmio_read_group, vgic_mmio_write_group, 4,
                 VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH(GICR_ISENABLER0,
+        REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_ISENABLER0,
                 vgic_mmio_read_enable, vgic_mmio_write_senable, 4,
                 VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH(GICR_ICENABLER0,
+        REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_ICENABLER0,
                 vgic_mmio_read_enable, vgic_mmio_write_cenable, 4,
                 VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH_UACCESS(GICR_ISPENDR0,
+        REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ISPENDR0,
                 vgic_mmio_read_pending, vgic_mmio_write_spending,
                 vgic_v3_uaccess_read_pending, vgic_v3_uaccess_write_pending, 4,
                 VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH_UACCESS(GICR_ICPENDR0,
+        REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ICPENDR0,
                 vgic_mmio_read_pending, vgic_mmio_write_cpending,
                 vgic_mmio_read_raz, vgic_mmio_uaccess_write_wi, 4,
                 VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH_UACCESS(GICR_ISACTIVER0,
+        REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ISACTIVER0,
                 vgic_mmio_read_active, vgic_mmio_write_sactive,
                 NULL, vgic_mmio_uaccess_write_sactive,
                 4, VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH_UACCESS(GICR_ICACTIVER0,
+        REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ICACTIVER0,
                 vgic_mmio_read_active, vgic_mmio_write_cactive,
                 NULL, vgic_mmio_uaccess_write_cactive,
                 4, VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH(GICR_IPRIORITYR0,
+        REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_IPRIORITYR0,
                 vgic_mmio_read_priority, vgic_mmio_write_priority, 32,
                 VGIC_ACCESS_32bit | VGIC_ACCESS_8bit),
-        REGISTER_DESC_WITH_LENGTH(GICR_ICFGR0,
+        REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_ICFGR0,
                 vgic_mmio_read_config, vgic_mmio_write_config, 8,
                 VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH(GICR_IGRPMODR0,
+        REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_IGRPMODR0,
                 vgic_mmio_read_raz, vgic_mmio_write_wi, 4,
                 VGIC_ACCESS_32bit),
-        REGISTER_DESC_WITH_LENGTH(GICR_NSACR,
+        REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_NSACR,
                 vgic_mmio_read_raz, vgic_mmio_write_wi, 4,
                 VGIC_ACCESS_32bit),
 };
@@ -609,9 +608,8 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu)
         struct vgic_dist *vgic = &kvm->arch.vgic;
         struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
         struct vgic_io_device *rd_dev = &vcpu->arch.vgic_cpu.rd_iodev;
-        struct vgic_io_device *sgi_dev = &vcpu->arch.vgic_cpu.sgi_iodev;
         struct vgic_redist_region *rdreg;
-        gpa_t rd_base, sgi_base;
+        gpa_t rd_base;
         int ret;
 
         if (!IS_VGIC_ADDR_UNDEF(vgic_cpu->rd_iodev.base_addr))
@@ -633,52 +631,31 @@ int vgic_register_redist_iodev(struct kvm_vcpu *vcpu)
         vgic_cpu->rdreg = rdreg;
 
         rd_base = rdreg->base + rdreg->free_index * KVM_VGIC_V3_REDIST_SIZE;
-        sgi_base = rd_base + SZ_64K;
 
         kvm_iodevice_init(&rd_dev->dev, &kvm_io_gic_ops);
         rd_dev->base_addr = rd_base;
         rd_dev->iodev_type = IODEV_REDIST;
-        rd_dev->regions = vgic_v3_rdbase_registers;
-        rd_dev->nr_regions = ARRAY_SIZE(vgic_v3_rdbase_registers);
+        rd_dev->regions = vgic_v3_rd_registers;
+        rd_dev->nr_regions = ARRAY_SIZE(vgic_v3_rd_registers);
         rd_dev->redist_vcpu = vcpu;
 
         mutex_lock(&kvm->slots_lock);
         ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, rd_base,
-                                      SZ_64K, &rd_dev->dev);
+                                      2 * SZ_64K, &rd_dev->dev);
         mutex_unlock(&kvm->slots_lock);
 
         if (ret)
                 return ret;
 
-        kvm_iodevice_init(&sgi_dev->dev, &kvm_io_gic_ops);
-        sgi_dev->base_addr = sgi_base;
-        sgi_dev->iodev_type = IODEV_REDIST;
-        sgi_dev->regions = vgic_v3_sgibase_registers;
-        sgi_dev->nr_regions = ARRAY_SIZE(vgic_v3_sgibase_registers);
-        sgi_dev->redist_vcpu = vcpu;
-
-        mutex_lock(&kvm->slots_lock);
-        ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, sgi_base,
-                                      SZ_64K, &sgi_dev->dev);
-        if (ret) {
-                kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS,
-                                          &rd_dev->dev);
-                goto out;
-        }
-
         rdreg->free_index++;
-out:
-        mutex_unlock(&kvm->slots_lock);
-        return ret;
+        return 0;
 }
 
 static void vgic_unregister_redist_iodev(struct kvm_vcpu *vcpu)
 {
         struct vgic_io_device *rd_dev = &vcpu->arch.vgic_cpu.rd_iodev;
-        struct vgic_io_device *sgi_dev = &vcpu->arch.vgic_cpu.sgi_iodev;
 
         kvm_io_bus_unregister_dev(vcpu->kvm, KVM_MMIO_BUS, &rd_dev->dev);
-        kvm_io_bus_unregister_dev(vcpu->kvm, KVM_MMIO_BUS, &sgi_dev->dev);
 }
 
 static int vgic_register_all_redist_iodevs(struct kvm *kvm)
@@ -828,8 +805,8 @@ int vgic_v3_has_attr_regs(struct kvm_device *dev, struct kvm_device_attr *attr)
                 iodev.base_addr = 0;
                 break;
         case KVM_DEV_ARM_VGIC_GRP_REDIST_REGS:{
-                iodev.regions = vgic_v3_rdbase_registers;
-                iodev.nr_regions = ARRAY_SIZE(vgic_v3_rdbase_registers);
+                iodev.regions = vgic_v3_rd_registers;
+                iodev.nr_regions = ARRAY_SIZE(vgic_v3_rd_registers);
                 iodev.base_addr = 0;
                 break;
         }
@@ -987,21 +964,11 @@ int vgic_v3_redist_uaccess(struct kvm_vcpu *vcpu, bool is_write,
                            int offset, u32 *val)
 {
         struct vgic_io_device rd_dev = {
-                .regions = vgic_v3_rdbase_registers,
-                .nr_regions = ARRAY_SIZE(vgic_v3_rdbase_registers),
+                .regions = vgic_v3_rd_registers,
+                .nr_regions = ARRAY_SIZE(vgic_v3_rd_registers),
         };
 
-        struct vgic_io_device sgi_dev = {
-                .regions = vgic_v3_sgibase_registers,
-                .nr_regions = ARRAY_SIZE(vgic_v3_sgibase_registers),
-        };
-
-        /* SGI_base is the next 64K frame after RD_base */
-        if (offset >= SZ_64K)
-                return vgic_uaccess(vcpu, &sgi_dev, is_write, offset - SZ_64K,
-                                    val);
-        else
-                return vgic_uaccess(vcpu, &rd_dev, is_write, offset, val);
+        return vgic_uaccess(vcpu, &rd_dev, is_write, offset, val);
 }
 
 int vgic_v3_line_level_info_uaccess(struct kvm_vcpu *vcpu, bool is_write,