Re: [PATCH v7 10/17] KVM: arm64: introduce new KVM ITS device

[Andre Przywara <andre.przywara@arm.com>]

Hi,

On 04/07/16 10:00, Auger Eric wrote:
> Hi Andre,
> 
> On 28/06/2016 14:32, Andre Przywara wrote:
>> Introduce a new KVM device that represents an ARM Interrupt Translation
>> Service (ITS) controller. Since there can be multiple of this per guest,
>> we can't piggy back on the existing GICv3 distributor device, but create
>> a new type of KVM device.
>> On the KVM_CREATE_DEVICE ioctl we allocate and initialize the ITS data
>> structure and store the pointer in the kvm_device data.
>> Upon an explicit init ioctl from userland (after having setup the MMIO
>> address) we register the handlers with the kvm_io_bus framework.
>> Any reference to an ITS thus has to go via this interface.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>>  Documentation/virtual/kvm/devices/arm-vgic.txt |  25 +++--
>>  arch/arm/kvm/arm.c                             |   1 +
>>  arch/arm64/include/uapi/asm/kvm.h              |   2 +
>>  include/kvm/vgic/vgic.h                        |   1 +
>>  include/uapi/linux/kvm.h                       |   2 +
>>  virt/kvm/arm/vgic/vgic-its.c                   | 127 ++++++++++++++++++++++++-
>>  virt/kvm/arm/vgic/vgic-kvm-device.c            |   7 +-
>>  virt/kvm/arm/vgic/vgic-mmio-v3.c               |   2 +-
>>  virt/kvm/arm/vgic/vgic.h                       |   8 ++
>>  9 files changed, 165 insertions(+), 10 deletions(-)
>>
>> diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt
>> index 59541d4..89182f8 100644
>> --- a/Documentation/virtual/kvm/devices/arm-vgic.txt
>> +++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
>> @@ -4,16 +4,22 @@ ARM Virtual Generic Interrupt Controller (VGIC)
>>  Device types supported:
>>    KVM_DEV_TYPE_ARM_VGIC_V2     ARM Generic Interrupt Controller v2.0
>>    KVM_DEV_TYPE_ARM_VGIC_V3     ARM Generic Interrupt Controller v3.0
>> +  KVM_DEV_TYPE_ARM_VGIC_ITS    ARM Interrupt Translation Service Controller
>>  
>> -Only one VGIC instance may be instantiated through either this API or the
>> -legacy KVM_CREATE_IRQCHIP api.  The created VGIC will act as the VM interrupt
>> -controller, requiring emulated user-space devices to inject interrupts to the
>> -VGIC instead of directly to CPUs.
>> +Only one VGIC instance of the V2/V3 types above may be instantiated through
>> +either this API or the legacy KVM_CREATE_IRQCHIP api.  The created VGIC will
>> +act as the VM interrupt controller, requiring emulated user-space devices to
>> +inject interrupts to the VGIC instead of directly to CPUs.
>>  
>>  Creating a guest GICv3 device requires a host GICv3 as well.
>>  GICv3 implementations with hardware compatibility support allow a guest GICv2
>>  as well.
>>  
>> +Creating a virtual ITS controller requires a host GICv3 (but does not depend
>> +on having physical ITS controllers).
>> +There can be multiple ITS controllers per guest, each of them has to have
>> +a separate, non-overlapping MMIO region.
>> +
>>  Groups:
>>    KVM_DEV_ARM_VGIC_GRP_ADDR
>>    Attributes:
>> @@ -39,6 +45,13 @@ Groups:
>>        Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
>>        This address needs to be 64K aligned.
>>  
>> +    KVM_VGIC_V3_ADDR_TYPE_ITS (rw, 64-bit)
>> +      Base address in the guest physical address space of the GICv3 ITS
>> +      control register frame. The ITS allows MSI(-X) interrupts to be
>> +      injected into guests. This extension is optional. If the kernel
>> +      does not support the ITS, the call returns -ENODEV.
>> +      Only valid for KVM_DEV_TYPE_ARM_VGIC_ITS.
>> +      This address needs to be 64K aligned and the region covers 128K.
>>  
>>    KVM_DEV_ARM_VGIC_GRP_DIST_REGS
>>    Attributes:
>> @@ -109,8 +122,8 @@ Groups:
>>    KVM_DEV_ARM_VGIC_GRP_CTRL
>>    Attributes:
>>      KVM_DEV_ARM_VGIC_CTRL_INIT
>> -      request the initialization of the VGIC, no additional parameter in
>> -      kvm_device_attr.addr.
>> +      request the initialization of the VGIC or ITS, no additional parameter
>> +      in kvm_device_attr.addr.
>>    Errors:
>>      -ENXIO: VGIC not properly configured as required prior to calling
>>       this attribute
>> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
>> index a268c85..f4a953e 100644
>> --- a/arch/arm/kvm/arm.c
>> +++ b/arch/arm/kvm/arm.c
>> @@ -20,6 +20,7 @@
>>  #include <linux/errno.h>
>>  #include <linux/err.h>
>>  #include <linux/kvm_host.h>
>> +#include <linux/list.h>
>>  #include <linux/module.h>
>>  #include <linux/vmalloc.h>
>>  #include <linux/fs.h>
>> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
>> index f209ea1..f8c257b 100644
>> --- a/arch/arm64/include/uapi/asm/kvm.h
>> +++ b/arch/arm64/include/uapi/asm/kvm.h
>> @@ -87,9 +87,11 @@ struct kvm_regs {
>>  /* Supported VGICv3 address types  */
>>  #define KVM_VGIC_V3_ADDR_TYPE_DIST	2
>>  #define KVM_VGIC_V3_ADDR_TYPE_REDIST	3
>> +#define KVM_VGIC_ITS_ADDR_TYPE		4
>>  
>>  #define KVM_VGIC_V3_DIST_SIZE		SZ_64K
>>  #define KVM_VGIC_V3_REDIST_SIZE		(2 * SZ_64K)
>> +#define KVM_VGIC_V3_ITS_SIZE		SZ_64K
>>  
>>  #define KVM_ARM_VCPU_POWER_OFF		0 /* CPU is started in OFF state */
>>  #define KVM_ARM_VCPU_EL1_32BIT		1 /* CPU running a 32bit VM */
>> diff --git a/include/kvm/vgic/vgic.h b/include/kvm/vgic/vgic.h
>> index 949a0e1..8cec203 100644
>> --- a/include/kvm/vgic/vgic.h
>> +++ b/include/kvm/vgic/vgic.h
>> @@ -159,6 +159,7 @@ struct vgic_dist {
>>  
>>  	struct vgic_io_device	dist_iodev;
>>  
>> +	bool			has_its;
>>  	/*
>>  	 * Contains the address of the LPI configuration table.
>>  	 * Since we report GICR_TYPER.CommonLPIAff as 0b00, we can share
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 7de96f5..d8c4c32 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -1077,6 +1077,8 @@ enum kvm_device_type {
>>  #define KVM_DEV_TYPE_FLIC		KVM_DEV_TYPE_FLIC
>>  	KVM_DEV_TYPE_ARM_VGIC_V3,
>>  #define KVM_DEV_TYPE_ARM_VGIC_V3	KVM_DEV_TYPE_ARM_VGIC_V3
>> +	KVM_DEV_TYPE_ARM_VGIC_ITS,
>> +#define KVM_DEV_TYPE_ARM_VGIC_ITS	KVM_DEV_TYPE_ARM_VGIC_ITS
>>  	KVM_DEV_TYPE_MAX,
>>  };
>>  
>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>> index ab8d244..62d7484 100644
>> --- a/virt/kvm/arm/vgic/vgic-its.c
>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>> @@ -21,6 +21,7 @@
>>  #include <linux/kvm.h>
>>  #include <linux/kvm_host.h>
>>  #include <linux/interrupt.h>
>> +#include <linux/uaccess.h>
>>  
>>  #include <linux/irqchip/arm-gic-v3.h>
>>  
>> @@ -80,7 +81,7 @@ static struct vgic_register_region its_registers[] = {
>>  		VGIC_ACCESS_32bit),
>>  };
>>  
>> -int vits_register(struct kvm *kvm, struct vgic_its *its)
>> +static int vits_register(struct kvm *kvm, struct vgic_its *its)
>>  {
>>  	struct vgic_io_device *iodev = &its->iodev;
>>  	int ret;
>> @@ -98,3 +99,127 @@ int vits_register(struct kvm *kvm, struct vgic_its *its)
>>  
>>  	return ret;
>>  }
>> +
>> +static int vgic_its_create(struct kvm_device *dev, u32 type)
>> +{
>> +	struct vgic_its *its;
>> +
>> +	if (type != KVM_DEV_TYPE_ARM_VGIC_ITS)
>> +		return -ENODEV;
>> +
>> +	its = kzalloc(sizeof(struct vgic_its), GFP_KERNEL);
>> +	if (!its)
>> +		return -ENOMEM;
>> +
>> +	its->vgic_its_base = VGIC_ADDR_UNDEF;
>> +
>> +	dev->kvm->arch.vgic.has_its = true;
>> +	its->enabled = false;
>> +
>> +	dev->private = its;
>> +
>> +	return 0;
>> +}
>> +
>> +static void vgic_its_destroy(struct kvm_device *kvm_dev)
>> +{
>> +	struct vgic_its *its = kvm_dev->private;
>> +
>> +	kfree(its);
>> +}
>> +
>> +static int vgic_its_has_attr(struct kvm_device *dev,
>> +			     struct kvm_device_attr *attr)
>> +{
>> +	switch (attr->group) {
>> +	case KVM_DEV_ARM_VGIC_GRP_ADDR:
>> +		switch (attr->attr) {
>> +		case KVM_VGIC_ITS_ADDR_TYPE:
>> +			return 0;
>> +		}
>> +		break;
>> +	case KVM_DEV_ARM_VGIC_GRP_CTRL:
>> +		switch (attr->attr) {
>> +		case KVM_DEV_ARM_VGIC_CTRL_INIT:
>> +			return 0;
>> +		}
>> +		break;
>> +	}
>> +	return -ENXIO;
>> +}
>> +
>> +static int vgic_its_set_attr(struct kvm_device *dev,
>> +			     struct kvm_device_attr *attr)
>> +{
>> +	struct vgic_its *its = dev->private;
>> +	int ret;
>> +
>> +	switch (attr->group) {
>> +	case KVM_DEV_ARM_VGIC_GRP_ADDR: {
>> +		u64 __user *uaddr = (u64 __user *)(long)attr->addr;
>> +		unsigned long type = (unsigned long)attr->attr;
>> +		u64 addr;
>> +
>> +		if (type != KVM_VGIC_ITS_ADDR_TYPE)
>> +			return -ENODEV;
>> +
>> +		if (copy_from_user(&addr, uaddr, sizeof(addr)))
>> +			return -EFAULT;
>> +
>> +		ret = vgic_check_ioaddr(dev->kvm, &its->vgic_its_base,
>> +					addr, SZ_64K);
>> +		if (ret)
>> +			return ret;
>> +
>> +		its->vgic_its_base = addr;
>> +
>> +		return 0;
>> +	}
>> +	case KVM_DEV_ARM_VGIC_GRP_CTRL:
>> +		switch (attr->attr) {
>> +		case KVM_DEV_ARM_VGIC_CTRL_INIT:
>> +			return vits_register(dev->kvm, its);
> This does not look homogeneous with the GICv2/3 code init sequence
> 
> on vgic GICv2/v3 KVM_DEV_ARM_VGIC_GRP_CTRL/KVM_DEV_ARM_VGIC_CTRL_INIT
> we call vgic_init/kvm_vgic_dist_init/kvm_vgic_vcpu_init.
> 
> the kvm_vgic_map_resources was responsible for registering the iodevs.
> this was called on kvm_vcpu_first_run_init.

Which I think is something that we do for keeping compatibility with the
older lazy VGIC init sequence only?

> Here for ITS you propose to do the iodev registration on
> KVM_DEV_ARM_VGIC_CTRL_INIT

I think it's more logical to do it then. With CTRL_INIT userland
signalizes that it's done with the setup, so we can setup everything.

> From a QEMU integration point of view this means the init sequence used
> for KVM GIC interrupt controllers cannot be reused for ITS and more
> importantly this is not straightforward to have the proper sequence
> ordering (hence the previously reported case).

I am confused, can you please elaborate what the problem is?
Or alternatively sketch what you ideally would the ITS init sequence to
look like? I am totally open to any changes, just need to know what
you/QEMU needs.

Cheers,
Andre.


> Why not offering a similar mechanism?
> 
> Thanks
> 
> Eric
> 
> 
> 
> 
> 
>> +		}
>> +		break;
>> +	}
>> +	return -ENXIO;
>> +}
>> +
>> +static int vgic_its_get_attr(struct kvm_device *dev,
>> +			     struct kvm_device_attr *attr)
>> +{
>> +	switch (attr->group) {
>> +	case KVM_DEV_ARM_VGIC_GRP_ADDR: {
>> +		struct vgic_its *its = dev->private;
>> +		u64 addr = its->vgic_its_base;
>> +		u64 __user *uaddr = (u64 __user *)(long)attr->addr;
>> +		unsigned long type = (unsigned long)attr->attr;
>> +
>> +		if (type != KVM_VGIC_ITS_ADDR_TYPE)
>> +			return -ENODEV;
>> +
>> +		if (copy_to_user(uaddr, &addr, sizeof(addr)))
>> +			return -EFAULT;
>> +		break;
>> +	default:
>> +		return -ENXIO;
>> +	}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +struct kvm_device_ops kvm_arm_vgic_its_ops = {
>> +	.name = "kvm-arm-vgic-its",
>> +	.create = vgic_its_create,
>> +	.destroy = vgic_its_destroy,
>> +	.set_attr = vgic_its_set_attr,
>> +	.get_attr = vgic_its_get_attr,
>> +	.has_attr = vgic_its_has_attr,
>> +};
>> +
>> +int kvm_vgic_register_its_device(void)
>> +{
>> +	return kvm_register_device_ops(&kvm_arm_vgic_its_ops,
>> +				       KVM_DEV_TYPE_ARM_VGIC_ITS);
>> +}
>> diff --git a/virt/kvm/arm/vgic/vgic-kvm-device.c b/virt/kvm/arm/vgic/vgic-kvm-device.c
>> index 2f24f13..1813f93 100644
>> --- a/virt/kvm/arm/vgic/vgic-kvm-device.c
>> +++ b/virt/kvm/arm/vgic/vgic-kvm-device.c
>> @@ -21,8 +21,8 @@
>>  
>>  /* common helpers */
>>  
>> -static int vgic_check_ioaddr(struct kvm *kvm, phys_addr_t *ioaddr,
>> -			     phys_addr_t addr, phys_addr_t alignment)
>> +int vgic_check_ioaddr(struct kvm *kvm, phys_addr_t *ioaddr,
>> +		      phys_addr_t addr, phys_addr_t alignment)
>>  {
>>  	if (addr & ~KVM_PHYS_MASK)
>>  		return -E2BIG;
>> @@ -223,6 +223,9 @@ int kvm_register_vgic_device(unsigned long type)
>>  	case KVM_DEV_TYPE_ARM_VGIC_V3:
>>  		ret = kvm_register_device_ops(&kvm_arm_vgic_v3_ops,
>>  					      KVM_DEV_TYPE_ARM_VGIC_V3);
>> +		if (ret)
>> +			break;
>> +		ret = kvm_vgic_register_its_device();
>>  		break;
>>  #endif
>>  	}
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> index 5fcc33a..9bcffa6 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> @@ -49,7 +49,7 @@ bool vgic_has_its(struct kvm *kvm)
>>  	if (dist->vgic_model != KVM_DEV_TYPE_ARM_VGIC_V3)
>>  		return false;
>>  
>> -	return false;
>> +	return dist->has_its;
>>  }
>>  
>>  static unsigned long vgic_mmio_read_v3_misc(struct kvm_vcpu *vcpu,
>> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
>> index 31807c1..9dc7207 100644
>> --- a/virt/kvm/arm/vgic/vgic.h
>> +++ b/virt/kvm/arm/vgic/vgic.h
>> @@ -42,6 +42,9 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq);
>>  bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq);
>>  void vgic_kick_vcpus(struct kvm *kvm);
>>  
>> +int vgic_check_ioaddr(struct kvm *kvm, phys_addr_t *ioaddr,
>> +		      phys_addr_t addr, phys_addr_t alignment);
>> +
>>  void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu);
>>  void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu);
>>  void vgic_v2_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr);
>> @@ -73,6 +76,7 @@ int vgic_v3_probe(const struct gic_kvm_info *info);
>>  int vgic_v3_map_resources(struct kvm *kvm);
>>  int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t dist_base_address);
>>  bool vgic_has_its(struct kvm *kvm);
>> +int kvm_vgic_register_its_device(void);
>>  #else
>>  static inline void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu)
>>  {
>> @@ -130,6 +134,10 @@ static inline bool vgic_has_its(struct kvm *kvm)
>>  	return false;
>>  }
>>  
>> +static inline int kvm_vgic_register_its_device(void)
>> +{
>> +	return -ENODEV;
>> +}
>>  #endif
>>  
>>  int kvm_register_vgic_device(unsigned long type);
>>
>