Re: [PATCH v2 8/8] arm: use new irqchip parameter to create different vGIC types

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

On 05/06/15 09:37, Andre Przywara wrote:
> Currently we unconditionally create a virtual GICv2 in the guest.
> Add a --irqchip= parameter to let the user specify a different GIC
> type for the guest.
> For now we the only other supported type is GICv3.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  arm/aarch64/arm-cpu.c                    |  2 +-
>  arm/gic.c                                | 21 +++++++++++++++++++++
>  arm/include/arm-common/kvm-config-arch.h |  9 ++++++++-
>  arm/kvm-cpu.c                            |  6 ++++++
>  arm/kvm.c                                |  4 +++-
>  5 files changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/arm/aarch64/arm-cpu.c b/arm/aarch64/arm-cpu.c
> index f702b9e..3dc8ea3 100644
> --- a/arm/aarch64/arm-cpu.c
> +++ b/arm/aarch64/arm-cpu.c
> @@ -12,7 +12,7 @@
>  static void generate_fdt_nodes(void *fdt, struct kvm *kvm, u32 gic_phandle)
>  {
>  	int timer_interrupts[4] = {13, 14, 11, 10};
> -	gic__generate_fdt_nodes(fdt, gic_phandle, IRQCHIP_GICV2);
> +	gic__generate_fdt_nodes(fdt, gic_phandle, kvm->cfg.arch.irqchip);
>  	timer__generate_fdt_nodes(fdt, kvm, timer_interrupts);
>  }
>  
> diff --git a/arm/gic.c b/arm/gic.c
> index c50d662..ab0f594 100644
> --- a/arm/gic.c
> +++ b/arm/gic.c
> @@ -21,6 +21,23 @@
>  static int gic_fd = -1;
>  static int nr_redists;
>  
> +int irqchip_parser(const struct option *opt, const char *arg, int unset)
> +{
> +	enum irqchip_type *type = opt->value;
> +
> +	*type = IRQCHIP_DEFAULT;
> +	if (!strcmp(arg, "gicv2")) {
> +		*type = IRQCHIP_GICV2;
> +	} else if (!strcmp(arg, "gicv3")) {
> +		*type = IRQCHIP_GICV3;
> +	} else if (strcmp(arg, "default")) {
> +		fprintf(stderr, "irqchip: unknown type \"%s\"\n", arg);
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> +
>  static int gic__create_device(struct kvm *kvm, enum irqchip_type type)
>  {
>  	int err;
> @@ -121,6 +138,10 @@ int gic__create(struct kvm *kvm, enum irqchip_type type)
>  	case IRQCHIP_GICV2:
>  		max_cpus = GIC_MAX_CPUS;
>  		break;
> +	case IRQCHIP_GICV3:
> +		nr_redists = kvm->cfg.nrcpus;
> +		max_cpus = 255;

Having a #define for this would be nice. But more importantly, the
actual limit is the one KVM imposes, and the code should probably
reflect this.

> +		break;
>  	default:
>  		return -ENODEV;
>  	}
> diff --git a/arm/include/arm-common/kvm-config-arch.h b/arm/include/arm-common/kvm-config-arch.h
> index a8ebd94..ae4e89b 100644
> --- a/arm/include/arm-common/kvm-config-arch.h
> +++ b/arm/include/arm-common/kvm-config-arch.h
> @@ -8,8 +8,11 @@ struct kvm_config_arch {
>  	unsigned int	force_cntfrq;
>  	bool		virtio_trans_pci;
>  	bool		aarch32_guest;
> +	int		irqchip;
>  };
>  
> +int irqchip_parser(const struct option *opt, const char *arg, int unset);
> +
>  #define OPT_ARCH_RUN(pfx, cfg)							\
>  	pfx,									\
>  	ARM_OPT_ARCH_RUN(cfg)							\
> @@ -21,6 +24,10 @@ struct kvm_config_arch {
>  		     "updated to program CNTFRQ correctly*"),			\
>  	OPT_BOOLEAN('\0', "force-pci", &(cfg)->virtio_trans_pci,		\
>  		    "Force virtio devices to use PCI as their default "		\
> -		    "transport"),
> +		    "transport"),						\
> +        OPT_CALLBACK('\0', "irqchip", &(cfg)->irqchip,				\
> +		     "[gicv2|gicv3]",					\
> +		     "type of interrupt controller to emulate in the guest",	\
> +		     irqchip_parser, NULL),
>  
>  #endif /* ARM_COMMON__KVM_CONFIG_ARCH_H */
> diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
> index a3344fa..aacc172 100644
> --- a/arm/kvm-cpu.c
> +++ b/arm/kvm-cpu.c
> @@ -144,6 +144,12 @@ bool kvm_cpu__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data,
>  {
>  	int nr_redists = 0;
>  
> +	switch (vcpu->kvm->cfg.arch.irqchip) {
> +	case IRQCHIP_GICV3:
> +		nr_redists = vcpu->kvm->nrcpus;
> +		break;
> +	}
> +
>  	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)) {
> diff --git a/arm/kvm.c b/arm/kvm.c
> index f9685c2..2628d31 100644
> --- a/arm/kvm.c
> +++ b/arm/kvm.c
> @@ -82,6 +82,8 @@ void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size)
>  		MADV_MERGEABLE | MADV_HUGEPAGE);
>  
>  	/* Create the virtual GIC. */
> -	if (gic__create(kvm, IRQCHIP_GICV2))
> +	if (kvm->cfg.arch.irqchip == IRQCHIP_DEFAULT)
> +		kvm->cfg.arch.irqchip = IRQCHIP_GICV2;
> +	if (gic__create(kvm, kvm->cfg.arch.irqchip))
>  		die("Failed to create virtual GIC");
>  }
> 

I think you really need to revisit this the way you propagate the GIC
stuff outside of the GIC code. IRQCHIP_DEFAULT should be IRQCHIP_GICV2,
there is no reason for it to be otherwise. Same goes for the nr_redists
thing. Keep it localized as much as possible, and only export synthetic
information to the rest of kvmtool.

Thanks,

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