[PATCH v3 32/55] KVM: arm/arm64: vgic-new: Add GICv3 MMIO handling framework

[christoffer.dall@linaro.org (Christoffer Dall)]

On Fri, May 06, 2016 at 11:45:45AM +0100, Andre Przywara wrote:
> Create a new file called vgic-mmio-v3.c and describe the GICv3
> distributor and redistributor registers there.
> This adds a special macro to deal with the split of SGI/PPI in the
> redistributor and SPIs in the distributor, which allows us to reuse
> the existing GICv2 handlers for those registers which are compatible.
> Also we provide a function to deal with the registration of the two
> separate redistributor frames per VCPU.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> Reviewed-by: Eric Auger <eric.auger@linaro.org>
> ---
> Changelog RFC..v1:
> - adapt to new MMIO registration approach:
>   register one device for the distributor and two for each VCPU
> - implement special handling for private interrupts
> - remove empty stub functions
> - make IGROUPR return RAO
> 
> Changelog v1 .. v2:
> - adapt to new framework, introduce vgic-mmio-v3.c
> - remove userland register access functions (for now)
> - precompute .len when describing a VGIC register
> - add missed pointer incrementation on registering redist regions
> - replace _nyi stub functions with raz/wi versions
> 
> Changelog v2 .. v3:
> - replace inclusion of kvm/vgic/vgic.h with kvm/arm_vgic.h
> - add prototype and stub code for vgic_register_redist_iodevs
> - rename register struct variables _rdbase_ and _sgibase_
> 
>  virt/kvm/arm/vgic/vgic-mmio-v3.c | 191 +++++++++++++++++++++++++++++++++++++++
>  virt/kvm/arm/vgic/vgic-mmio.c    |   5 +
>  virt/kvm/arm/vgic/vgic-mmio.h    |   2 +
>  virt/kvm/arm/vgic/vgic.h         |   7 ++
>  4 files changed, 205 insertions(+)
>  create mode 100644 virt/kvm/arm/vgic/vgic-mmio-v3.c
> 
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> new file mode 100644
> index 0000000..06c7ec5
> --- /dev/null
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -0,0 +1,191 @@
> +/*
> + * VGICv3 MMIO handling functions
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/irqchip/arm-gic-v3.h>
> +#include <linux/kvm.h>
> +#include <linux/kvm_host.h>
> +#include <kvm/iodev.h>
> +#include <kvm/arm_vgic.h>
> +
> +#include <asm/kvm_emulate.h>
> +
> +#include "vgic.h"
> +#include "vgic-mmio.h"
> +
> +/*
> + * The GICv3 per-IRQ registers are split to control PPIs and SGIs in the
> + * redistributors, while SPIs are covered by registers in the distributor
> + * block. Trying to set private IRQs in this block gets ignored.
> + * We take some special care here to fix the calculation of the register
> + * offset.
> + */
> +#define REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(off, read_ops, write_ops, bpi) \
> +	{								\
> +		.reg_offset = off,					\
> +		.bits_per_irq = bpi,					\
> +		.len = (bpi * VGIC_NR_PRIVATE_IRQS) / 8,		\
> +		.read = vgic_mmio_read_raz,				\
> +		.write = vgic_mmio_write_wi,				\
> +	}, {								\
> +		.reg_offset = off + (bpi * VGIC_NR_PRIVATE_IRQS) / 8,	\
> +		.bits_per_irq = bpi,					\
> +		.len = (bpi * (1024 - VGIC_NR_PRIVATE_IRQS)) / 8,	\
> +		.read = read_ops,					\
> +		.write = write_ops,					\
> +	}
> +
> +static const struct vgic_register_region vgic_v3_dist_registers[] = {
> +	REGISTER_DESC_WITH_LENGTH(GICD_CTLR,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 16),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IGROUPR,
> +		vgic_mmio_read_rao, vgic_mmio_write_wi, 1),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISENABLER,
> +		vgic_mmio_read_enable, vgic_mmio_write_senable, 1),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICENABLER,
> +		vgic_mmio_read_enable, vgic_mmio_write_cenable, 1),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISPENDR,
> +		vgic_mmio_read_pending, vgic_mmio_write_spending, 1),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICPENDR,
> +		vgic_mmio_read_pending, vgic_mmio_write_cpending, 1),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISACTIVER,
> +		vgic_mmio_read_active, vgic_mmio_write_sactive, 1),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICACTIVER,
> +		vgic_mmio_read_active, vgic_mmio_write_cactive, 1),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IPRIORITYR,
> +		vgic_mmio_read_priority, vgic_mmio_write_priority, 8),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ITARGETSR,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 8),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICFGR,
> +		vgic_mmio_read_config, vgic_mmio_write_config, 2),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IGRPMODR,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 1),
> +	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_IROUTER,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 64),
> +	REGISTER_DESC_WITH_LENGTH(GICD_IDREGS,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 48),
> +};
> +
> +static const struct vgic_register_region vgic_v3_rdbase_registers[] = {
> +	REGISTER_DESC_WITH_LENGTH(GICR_CTLR,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_IIDR,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_TYPER,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 8),
> +	REGISTER_DESC_WITH_LENGTH(GICR_PROPBASER,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 8),
> +	REGISTER_DESC_WITH_LENGTH(GICR_PENDBASER,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 8),
> +	REGISTER_DESC_WITH_LENGTH(GICR_IDREGS,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 48),
> +};
> +
> +static const struct vgic_register_region vgic_v3_sgibase_registers[] = {
> +	REGISTER_DESC_WITH_LENGTH(GICR_IGROUPR0,
> +		vgic_mmio_read_rao, vgic_mmio_write_wi, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_ISENABLER0,
> +		vgic_mmio_read_enable, vgic_mmio_write_senable, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_ICENABLER0,
> +		vgic_mmio_read_enable, vgic_mmio_write_cenable, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_ISPENDR0,
> +		vgic_mmio_read_pending, vgic_mmio_write_spending, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_ICPENDR0,
> +		vgic_mmio_read_pending, vgic_mmio_write_cpending, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_ISACTIVER0,
> +		vgic_mmio_read_active, vgic_mmio_write_sactive, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_ICACTIVER0,
> +		vgic_mmio_read_active, vgic_mmio_write_cactive, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_IPRIORITYR0,
> +		vgic_mmio_read_priority, vgic_mmio_write_priority, 32),
> +	REGISTER_DESC_WITH_LENGTH(GICR_ICFGR0,
> +		vgic_mmio_read_config, vgic_mmio_write_config, 8),
> +	REGISTER_DESC_WITH_LENGTH(GICR_IGRPMODR0,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 4),
> +	REGISTER_DESC_WITH_LENGTH(GICR_NSACR,
> +		vgic_mmio_read_raz, vgic_mmio_write_wi, 4),
> +};
> +
> +unsigned int vgic_v3_init_dist_iodev(struct vgic_io_device *dev)
> +{
> +	dev->regions = vgic_v3_dist_registers;
> +	dev->nr_regions = ARRAY_SIZE(vgic_v3_dist_registers);
> +
> +	kvm_iodevice_init(&dev->dev, &kvm_io_gic_ops);
> +
> +	return SZ_64K;
> +}
> +
> +int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t redist_base_address)
> +{
> +	int nr_vcpus = atomic_read(&kvm->online_vcpus);
> +	struct kvm_vcpu *vcpu;
> +	struct vgic_io_device *devices, *device;
> +	int c, ret = 0;
> +
> +	devices = kmalloc(sizeof(struct vgic_io_device) * nr_vcpus * 2,
> +			  GFP_KERNEL);
> +	if (!devices)
> +		return -ENOMEM;
> +
> +	device = devices;
> +	kvm_for_each_vcpu(c, vcpu, kvm) {
> +		kvm_iodevice_init(&device->dev, &kvm_io_gic_ops);
> +		device->base_addr = redist_base_address;
> +		device->regions = vgic_v3_rdbase_registers;
> +		device->nr_regions = ARRAY_SIZE(vgic_v3_rdbase_registers);
> +		device->redist_vcpu = vcpu;
> +
> +		mutex_lock(&kvm->slots_lock);
> +		ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS,
> +					      redist_base_address,
> +					      SZ_64K, &device->dev);
> +		mutex_unlock(&kvm->slots_lock);
> +
> +		if (ret)
> +			break;
> +
> +		device++;
> +		kvm_iodevice_init(&device->dev, &kvm_io_gic_ops);
> +		device->base_addr = redist_base_address + SZ_64K;
> +		device->regions = vgic_v3_sgibase_registers;
> +		device->nr_regions = ARRAY_SIZE(vgic_v3_sgibase_registers);
> +		device->redist_vcpu = vcpu;
> +
> +		mutex_lock(&kvm->slots_lock);
> +		ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS,
> +					      redist_base_address + SZ_64K,
> +					      SZ_64K, &device->dev);
> +		mutex_unlock(&kvm->slots_lock);
> +		if (ret) {
> +			kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS,
> +						  &devices[c * 2].dev);
> +			break;
> +		}
> +		device++;
> +		redist_base_address += 2 * SZ_64K;

while I think this whole thing is actually correct, I think it could
have been much more clear by, in the beginning of the loop doing:

	gpa_t rd_base = redist_base_address + c * SZ_64K * 2;
	gpa_t sgi_base = rd_base + SZ_64K;
	struct vgic_io_device *rd_dev = &devices[c];
	struct vgic_io_device *sgi_dev = &devices[c + 1];

and then referring directly to these variables.

> +	}
> +
> +	if (ret) {
> +		for (c--; c >= 0; c--) {

holy dark mother of all that's evil; I think this is correct.

> +			kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS,
> +						  &devices[c * 2].dev);
> +			kvm_io_bus_unregister_dev(kvm, KVM_MMIO_BUS,
> +						  &devices[c * 2 + 1].dev);

do we really need this though?  Can't we just rely on KVM to tear down
thew whole bus infrastructure as we're returning an error anyway?

(have you looked at what the unregister_dev function does, it's full of
kmallocs and other fun stuff).


Thanks,
-Christoffer

> +		}
> +		kfree(devices);
> +	} else {
> +		kvm->arch.vgic.redist_iodevs = devices;
> +	}
> +
> +	return ret;
> +}
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
> index 19fed56..d1b88d2 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
> @@ -502,6 +502,11 @@ int vgic_register_dist_iodev(struct kvm *kvm, gpa_t dist_base_address,
>  	case VGIC_V2:
>  		len = vgic_v2_init_dist_iodev(io_device);
>  		break;
> +#ifdef CONFIG_KVM_ARM_VGIC_V3
> +	case VGIC_V3:
> +		len = vgic_v3_init_dist_iodev(io_device);
> +		break;
> +#endif
>  	default:
>  		BUG_ON(1);
>  	}
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
> index 884eb71..3585ac6 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.h
> +++ b/virt/kvm/arm/vgic/vgic-mmio.h
> @@ -123,4 +123,6 @@ void vgic_mmio_write_config(struct kvm_vcpu *vcpu,
>  
>  unsigned int vgic_v2_init_dist_iodev(struct vgic_io_device *dev);
>  
> +unsigned int vgic_v3_init_dist_iodev(struct vgic_io_device *dev);
> +
>  #endif
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index cf62015..39a8a65 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -40,6 +40,7 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu);
>  void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr);
>  void vgic_v3_clear_lr(struct kvm_vcpu *vcpu, int lr);
>  void vgic_v3_set_underflow(struct kvm_vcpu *vcpu);
> +int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t dist_base_address);
>  #else
>  static inline void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu)
>  {
> @@ -61,6 +62,12 @@ static inline void vgic_v3_clear_lr(struct kvm_vcpu *vcpu, int lr)
>  static inline void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
>  {
>  }
> +
> +static inline int vgic_register_redist_iodevs(struct kvm *kvm,
> +					      gpa_t dist_base_address)
> +{
> +	return -ENODEV;
> +}
>  #endif
>  
>  #endif
> -- 
> 2.7.3
>