Re: [PATCH v4 03/12] KVM: arm64: Introduce new MMIO region for the ITS base address

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

On 05/05/16 19:08, Chalamarla, Tirumalesh wrote:
> 
> 
> 
> 
> 
> On 3/25/16, 7:14 PM, "kvmarm-bounces@lists.cs.columbia.edu on behalf of Andre Przywara" <kvmarm-bounces@lists.cs.columbia.edu on behalf of andre.przywara@arm.com> wrote:
> 
>> The ARM GICv3 ITS controller requires a separate register frame to
>> cover ITS specific registers. Add a new VGIC address type and store
>> the address in a field in the vgic_dist structure.
>> Provide a function to check whether userland has provided the address,
>> so ITS functionality can be guarded by that check.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>> Documentation/virtual/kvm/devices/arm-vgic.txt |  9 +++++++++
>> arch/arm64/include/uapi/asm/kvm.h              |  2 ++
>> include/kvm/vgic/vgic.h                        |  5 +++++
>> virt/kvm/arm/vgic/vgic.c                       | 10 ++++++++++
>> virt/kvm/arm/vgic/vgic_init.c                  |  1 +
>> virt/kvm/arm/vgic/vgic_kvm_device.c            |  7 +++++++
>> 6 files changed, 34 insertions(+)
>>
>> diff --git a/Documentation/virtual/kvm/devices/arm-vgic.txt b/Documentation/virtual/kvm/devices/arm-vgic.txt
>> index 59541d4..087e2d9 100644
>> --- a/Documentation/virtual/kvm/devices/arm-vgic.txt
>> +++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
>> @@ -39,6 +39,15 @@ 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.
>> +      This memory is solely for the guest to access the ITS control
>> +      registers and does not cover the ITS translation register.
>> +      Only valid for KVM_DEV_TYPE_ARM_VGIC_V3.
>> +      This address needs to be 64K aligned and the region covers 64 KByte.
>>
>>   KVM_DEV_ARM_VGIC_GRP_DIST_REGS
>>   Attributes:
>> diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
>> index f209ea1..c2b257d 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_V3_ADDR_TYPE_ITS	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 7c1d145..11344e6 100644
>> --- a/include/kvm/vgic/vgic.h
>> +++ b/include/kvm/vgic/vgic.h
>> @@ -135,6 +135,9 @@ struct vgic_dist {
>> 		gpa_t			vgic_redist_base;
>> 	};
>>
>> +	/* The base address of the ITS control register frame */
>> +	gpa_t			vgic_its_base;
>> +
>> 	/* distributor enabled */
>> 	u32			enabled;
>>
>> @@ -253,4 +256,6 @@ static inline int kvm_vgic_get_max_vcpus(void)
>> 	return kvm_vgic_global_state.max_gic_vcpus;
>> }
>>
>> +bool vgic_has_its(struct kvm *kvm);
>> +
>> #endif /* __ASM_ARM_KVM_VGIC_VGIC_H */
>> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
>> index 65395af..1de2478 100644
>> --- a/virt/kvm/arm/vgic/vgic.c
>> +++ b/virt/kvm/arm/vgic/vgic.c
>> @@ -612,3 +612,13 @@ bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, u32 intid)
>>
>> 	return map_is_active;
>> }
>> +
>> +bool vgic_has_its(struct kvm *kvm)
>> +{
>> +	struct vgic_dist *dist = &kvm->arch.vgic;
>> +
>> +	if (dist->vgic_model != KVM_DEV_TYPE_ARM_VGIC_V3)
>> +		return false;
>> +
>> +	return !IS_VGIC_ADDR_UNDEF(dist->vgic_its_base);
>> +}
>> diff --git a/virt/kvm/arm/vgic/vgic_init.c b/virt/kvm/arm/vgic/vgic_init.c
>> index ac655b5..2301e03 100644
>> --- a/virt/kvm/arm/vgic/vgic_init.c
>> +++ b/virt/kvm/arm/vgic/vgic_init.c
>> @@ -132,6 +132,7 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
>> 	kvm->arch.vgic.vgic_dist_base = VGIC_ADDR_UNDEF;
>> 	kvm->arch.vgic.vgic_cpu_base = VGIC_ADDR_UNDEF;
>> 	kvm->arch.vgic.vgic_redist_base = VGIC_ADDR_UNDEF;
>> +	kvm->arch.vgic.vgic_its_base = VGIC_ADDR_UNDEF;
>>
>> out_unlock:
>> 	for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {
>> diff --git a/virt/kvm/arm/vgic/vgic_kvm_device.c b/virt/kvm/arm/vgic/vgic_kvm_device.c
>> index 7f78a16..3ec2ac3 100644
>> --- a/virt/kvm/arm/vgic/vgic_kvm_device.c
>> +++ b/virt/kvm/arm/vgic/vgic_kvm_device.c
>> @@ -109,6 +109,12 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
>> 		block_size = KVM_VGIC_V3_REDIST_SIZE;
>> 		alignment = SZ_64K;
>> 		break;
>> +	case KVM_VGIC_V3_ADDR_TYPE_ITS:
>> +		type_needed = KVM_DEV_TYPE_ARM_VGIC_V3;
>> +		addr_ptr = &vgic->vgic_its_base;
>> +		block_size = KVM_VGIC_V3_ITS_SIZE;
>> +		alignment = SZ_64K;
>> +		break;
> 
> Should there be a check based on number of vcpus? 

Why would the number of vcpus influence the size of the ITS?

Thanks,

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