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

From: [email-masked] (Andre Przywara)
Date: Mon, 15 Jun 2015 12:12:48 +0100

On 06/10/2015 06:40 PM, Marc Zyngier wrote:
> 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 <[email-masked]>
>> ---
>>  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...

Sorry, rebasing artefact, this gets amended in the next patch. I have
fixed it now in here.

>>  
>>  	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.

Agreed, that looks much nicer now that I use a separate variable for the
GIC redist base address (instead of nr_redist).

>>  
>>  	_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.

Looking more closely at the code I wonder why we differentiate beyond
the IO port region anyway. I rewrote this now without actually checking
for the GIC region at all. This simplified a lot and allows us to get
rid of nr_redists completely.

Cheers,
Andre.