Re: [PATCH v2 7/8] arm: add support for supplying GICv3 redistributor addresses

[Marc Zyngier <marc.zyngier@arm.com>]

On 05/06/15 09:37, Andre Przywara wrote:
> The code currently is assuming fixed sized memory regions for the
> distributor and CPU interface. GICv3 needs a dynamic allocation of
> its redistributor region, since its size depends on the number of
> vCPUs.
> Also add the necessary code to create a GICv3 IRQ chip instance.
> This contains some defines which are not (yet) in the (32 bit) header
> files to allow compilation for ARM.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  arm/gic.c                         | 37 +++++++++++++++++++++++++++++++++++--
>  arm/include/arm-common/gic.h      |  2 +-
>  arm/include/arm-common/kvm-arch.h | 18 ++++++++++++++----
>  arm/kvm-cpu.c                     |  4 +++-
>  4 files changed, 53 insertions(+), 8 deletions(-)
> 
> diff --git a/arm/gic.c b/arm/gic.c
> index 0ce40e4..c50d662 100644
> --- a/arm/gic.c
> +++ b/arm/gic.c
> @@ -9,13 +9,24 @@
>  #include <linux/kernel.h>
>  #include <linux/kvm.h>
>  
> +/* Those names are not defined for ARM (yet) */
> +#ifndef KVM_VGIC_V3_ADDR_TYPE_DIST
> +#define KVM_VGIC_V3_ADDR_TYPE_DIST 2
> +#endif
> +
> +#ifndef KVM_VGIC_V3_ADDR_TYPE_REDIST
> +#define KVM_VGIC_V3_ADDR_TYPE_REDIST 3
> +#endif
> +
>  static int gic_fd = -1;
> +static int nr_redists;

Who sets this variable?
>  
>  static int gic__create_device(struct kvm *kvm, enum irqchip_type type)
>  {
>  	int err;
>  	u64 cpu_if_addr = ARM_GIC_CPUI_BASE;
>  	u64 dist_addr = ARM_GIC_DIST_BASE;
> +	u64 redist_addr = dist_addr - nr_redists * ARM_GIC_REDIST_SIZE;

You are doing a similar offsetting further down. Consider having a macro
that computes the redist base from the dist base.

>  	struct kvm_create_device gic_device = {
>  		.flags	= 0,
>  	};
> @@ -28,11 +39,19 @@ static int gic__create_device(struct kvm *kvm, enum irqchip_type type)
>  		.group	= KVM_DEV_ARM_VGIC_GRP_ADDR,
>  		.addr	= (u64)(unsigned long)&dist_addr,
>  	};
> +	struct kvm_device_attr redist_attr = {
> +		.group	= KVM_DEV_ARM_VGIC_GRP_ADDR,
> +		.attr	= KVM_VGIC_V3_ADDR_TYPE_REDIST,
> +		.addr	= (u64)(unsigned long)&redist_addr,
> +	};
>  
>  	switch (type) {
>  	case IRQCHIP_GICV2:
>  		gic_device.type = KVM_DEV_TYPE_ARM_VGIC_V2;
>  		break;
> +	case IRQCHIP_GICV3:
> +		gic_device.type = KVM_DEV_TYPE_ARM_VGIC_V3;
> +		break;
>  	default:
>  		return -ENODEV;
>  	}
> @@ -48,6 +67,10 @@ static int gic__create_device(struct kvm *kvm, enum irqchip_type type)
>  		dist_attr.attr = KVM_VGIC_V2_ADDR_TYPE_DIST;
>  		err = ioctl(gic_fd, KVM_SET_DEVICE_ATTR, &cpu_if_attr);
>  		break;
> +	case IRQCHIP_GICV3:
> +		dist_attr.attr = KVM_VGIC_V3_ADDR_TYPE_DIST;
> +		err = ioctl(gic_fd, KVM_SET_DEVICE_ATTR, &redist_attr);
> +		break;
>  	default:
>  		return -ENODEV;
>  	}
> @@ -55,6 +78,8 @@ static int gic__create_device(struct kvm *kvm, enum irqchip_type type)
>  		return err;
>  
>  	err = ioctl(gic_fd, KVM_SET_DEVICE_ATTR, &dist_attr);
> +	if (err)
> +		return err;

Looks like a fairly useless statement...

>  
>  	return err;
>  }
> @@ -162,17 +187,25 @@ void gic__generate_fdt_nodes(void *fdt, u32 phandle, enum irqchip_type type)
>  	u64 reg_prop[] = {
>  		cpu_to_fdt64(ARM_GIC_DIST_BASE),
>  		cpu_to_fdt64(ARM_GIC_DIST_SIZE),
> -		cpu_to_fdt64(ARM_GIC_CPUI_BASE),
> -		cpu_to_fdt64(ARM_GIC_CPUI_SIZE),
> +		0, 0,				/* to be filled */
>  	};
>  
>  	switch (type) {
>  	case IRQCHIP_GICV2:
>  		compatible = "arm,cortex-a15-gic";
> +		reg_prop[2] = ARM_GIC_CPUI_BASE;
> +		reg_prop[3] = ARM_GIC_CPUI_SIZE;
> +		break;
> +	case IRQCHIP_GICV3:
> +		compatible = "arm,gic-v3";
> +		reg_prop[2] = ARM_GIC_DIST_BASE - nr_redists * ARM_GIC_REDIST_SIZE;
> +		reg_prop[3] = ARM_GIC_REDIST_SIZE * nr_redists;
>  		break;
>  	default:
>  		return;
>  	}
> +	reg_prop[2] = cpu_to_fdt64(reg_prop[2]);
> +	reg_prop[3] = cpu_to_fdt64(reg_prop[3]);

I'd find it more readable if you did the cpu_to_fdt64() as part of the
initial assignment.

>  
>  	_FDT(fdt_begin_node(fdt, "intc"));
>  	_FDT(fdt_property_string(fdt, "compatible", compatible));
> diff --git a/arm/include/arm-common/gic.h b/arm/include/arm-common/gic.h
> index f5f6707..8d6ab01 100644
> --- a/arm/include/arm-common/gic.h
> +++ b/arm/include/arm-common/gic.h
> @@ -21,7 +21,7 @@
>  #define GIC_MAX_CPUS			8
>  #define GIC_MAX_IRQ			255
>  
> -enum irqchip_type {IRQCHIP_DEFAULT, IRQCHIP_GICV2};
> +enum irqchip_type {IRQCHIP_DEFAULT, IRQCHIP_GICV2, IRQCHIP_GICV3};
>  
>  struct kvm;
>  
> diff --git a/arm/include/arm-common/kvm-arch.h b/arm/include/arm-common/kvm-arch.h
> index 082131d..be66a76 100644
> --- a/arm/include/arm-common/kvm-arch.h
> +++ b/arm/include/arm-common/kvm-arch.h
> @@ -17,10 +17,8 @@
>  
>  #define ARM_GIC_DIST_BASE	(ARM_AXI_AREA - ARM_GIC_DIST_SIZE)
>  #define ARM_GIC_CPUI_BASE	(ARM_GIC_DIST_BASE - ARM_GIC_CPUI_SIZE)
> -#define ARM_GIC_SIZE		(ARM_GIC_DIST_SIZE + ARM_GIC_CPUI_SIZE)
>  
>  #define ARM_IOPORT_SIZE		(ARM_MMIO_AREA - ARM_IOPORT_AREA)
> -#define ARM_VIRTIO_MMIO_SIZE	(ARM_AXI_AREA - (ARM_MMIO_AREA + ARM_GIC_SIZE))
>  #define ARM_PCI_CFG_SIZE	(1ULL << 24)
>  #define ARM_PCI_MMIO_SIZE	(ARM_MEMORY_AREA - \
>  				(ARM_AXI_AREA + ARM_PCI_CFG_SIZE))
> @@ -30,6 +28,13 @@
>  #define KVM_PCI_MMIO_AREA	(KVM_PCI_CFG_AREA + ARM_PCI_CFG_SIZE)
>  #define KVM_VIRTIO_MMIO_AREA	ARM_MMIO_AREA
>  
> +/*
> + * On a GICv3 there must be one redistributor per vCPU.
> + * The value here is the size for one, we multiply this at runtime with
> + * the number of requested vCPUs to get the actual size.
> + */
> +#define ARM_GIC_REDIST_SIZE	0x20000
> +
>  #define KVM_IRQ_OFFSET		GIC_SPI_IRQ_BASE
>  
>  #define KVM_VM_TYPE		0
> @@ -45,9 +50,14 @@ static inline bool arm_addr_in_ioport_region(u64 phys_addr)
>  	return phys_addr >= KVM_IOPORT_AREA && phys_addr < limit;
>  }
>  
> -static inline bool arm_addr_in_virtio_mmio_region(u64 phys_addr)
> +static inline bool arm_addr_in_virtio_mmio_region(int nr_redists, u64 phys_addr)
>  {
> -	u64 limit = KVM_VIRTIO_MMIO_AREA + ARM_VIRTIO_MMIO_SIZE;
> +	u64 limit = ARM_AXI_AREA - ARM_GIC_DIST_SIZE;
> +
> +	if (nr_redists)
> +		limit -= ARM_GIC_REDIST_SIZE * nr_redists;
> +	else
> +		limit -= ARM_GIC_CPUI_SIZE;
>  	return phys_addr >= KVM_VIRTIO_MMIO_AREA && phys_addr < limit;
>  }
>  
> diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
> index ab08815..a3344fa 100644
> --- a/arm/kvm-cpu.c
> +++ b/arm/kvm-cpu.c
> @@ -142,7 +142,9 @@ bool kvm_cpu__handle_exit(struct kvm_cpu *vcpu)
>  bool kvm_cpu__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data,
>  			   u32 len, u8 is_write)
>  {
> -	if (arm_addr_in_virtio_mmio_region(phys_addr)) {
> +	int nr_redists = 0;
> +
> +	if (arm_addr_in_virtio_mmio_region(nr_redists, phys_addr)) {
>  		return kvm__emulate_mmio(vcpu, phys_addr, data, len, is_write);
>  	} else if (arm_addr_in_ioport_region(phys_addr)) {
>  		int direction = is_write ? KVM_EXIT_IO_OUT : KVM_EXIT_IO_IN;
> 

Ouch. This feels really ugly. Why don't you have the GIC code export a
structure that contains the boundaries of the GIC (irrespective of its
type), and use that to compute the limit? I don't think we want this
nr_redists to propagate beyond the GIC code at all.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...