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KVM: arm/arm64: vgic: Use a single IO device per redistributor
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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 <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
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@eauger
eauger authored and Marc Zyngier committed Aug 25, 2019
1 parent 926c615 commit 3109741
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Showing 3 changed files with 24 additions and 59 deletions.
1 change: 0 additions & 1 deletion include/kvm/arm_vgic.h
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Original file line number Diff line number Diff line change
Expand Up @@ -314,7 +314,6 @@ struct vgic_cpu {
* parts of the redistributor.
*/
struct vgic_io_device rd_iodev;
struct vgic_io_device sgi_iodev;
struct vgic_redist_region *rdreg;

/* Contains the attributes and gpa of the LPI pending tables. */
Expand Down
1 change: 0 additions & 1 deletion virt/kvm/arm/vgic/vgic-init.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down
81 changes: 24 additions & 57 deletions virt/kvm/arm/vgic/vgic-mmio-v3.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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),
Expand All @@ -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),
};
Expand Down Expand Up @@ -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))
Expand All @@ -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)
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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,
Expand Down

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