[PATCH v2 7/8] arm: add support for supplying GICv3 redistributor addresses
Marc Zyngier
marc.zyngier at arm.com
Mon Jun 15 04:56:13 PDT 2015
On 15/06/15 12:12, Andre Przywara wrote:
> 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 <andre.przywara at 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...
>
> 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.
Not sure about that. Returning to userspace on access to the vgic region
is a good indication that something went wrong (no GIC instantiated?).
M.
--
Jazz is not dead. It just smells funny...
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