Subject: [PATCH v2 7/7] KVM: arm: implement kvm_set_msi by gsi direct mapping

From: [email-masked] (Eric Auger)
Date: Mon, 03 Aug 2015 11:11:19 +0200

On 08/02/2015 10:23 PM, Andre Przywara wrote:
> On 31/07/15 13:59, Eric Auger wrote:
>> Hi Andre,
>> On 07/11/2015 01:17 AM, Andre Przywara wrote:
>>> On 09/07/15 09:22, Eric Auger wrote:
>>>> If the ITS modality is not available, let's simply support MSI
>>>> injection by transforming the MSI.data into an SPI ID.
>>>>
>>>> This becomes possible to use KVM_SIGNAL_MSI ioctl for arm too.
>>>>
>>>> Signed-off-by: Eric Auger <[email-masked]>
>>>>
>>>> ---
>>>>
>>>> v1 -> v2:
>>>> - introduce vgic_v2m_inject_msi in vgic-v2-emul.c following Andre's
>>>>   advice
>>>> ---
>>>>  arch/arm/kvm/Kconfig        |  1 +
>>>>  virt/kvm/arm/vgic-v2-emul.c | 12 ++++++++++++
>>>>  2 files changed, 13 insertions(+)
>>>>
>>>> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
>>>> index 151e710..0f58baf 100644
>>>> --- a/arch/arm/kvm/Kconfig
>>>> +++ b/arch/arm/kvm/Kconfig
>>>> @@ -31,6 +31,7 @@ config KVM
>>>>  	select KVM_VFIO
>>>>  	select HAVE_KVM_EVENTFD
>>>>  	select HAVE_KVM_IRQFD
>>>> +	select HAVE_KVM_MSI
>>>
>>> I wonder if this requires some more code to only advertise
>>> KVM_CAP_SIGNAL_MSI if userland actually sets up a GICv2M?
>>> Otherwise userland could get the idea of being able to inectj MSIs
>>> without the guest actually being prepared for that (because the GICv2M
>>> driver did not initialize).
>> Not sure I get what you mean here. By directly transforming the user
>> provided MSI msg into an SPI ID, do we really have to care about GICv2M?
> 
> By user provided message you mean from user space? So this is an
> emulated device, which the guest programs with an MSI payload and a
> doorbell address at least? So how would a guest know these things
> without having a MSI capable interrupt controller?
> 
> Or are we talking about different things here?

I meant GICv2m is emulated on user-side today so I don't see how the
kernel could check anything. For the MSI injection, in that case, we
only use irqfd standard IRQ injection.

Cheers

Eric
> 
> Cheers,
> Andre.
> 
>>
>> Best Regards
>>
>> Eric
>>>
>>> Cheers,
>>> Andre.
>>>
>>>>  	select HAVE_KVM_IRQCHIP
>>>>  	select HAVE_KVM_IRQ_ROUTING
>>>>  	depends on ARM_VIRT_EXT && ARM_LPAE && ARM_ARCH_TIMER
>>>> diff --git a/virt/kvm/arm/vgic-v2-emul.c b/virt/kvm/arm/vgic-v2-emul.c
>>>> index 1390797..43013cc 100644
>>>> --- a/virt/kvm/arm/vgic-v2-emul.c
>>>> +++ b/virt/kvm/arm/vgic-v2-emul.c
>>>> @@ -478,6 +478,17 @@ static bool vgic_v2_queue_sgi(struct kvm_vcpu *vcpu, int irq)
>>>>  }
>>>>  
>>>>  /**
>>>> + * Emulates GICv2M MSI injection by injecting the SPI ID matching
>>>> + * the msi data
>>>> + * @kvm: pointer to the kvm struct
>>>> + * @msi: the msi struct handle
>>>> + */
>>>> +static int vgic_v2m_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
>>>> +{
>>>> +	return kvm_vgic_inject_irq(kvm, 0, msi->data, 1);
>>>> +}
>>>> +
>>>> +/**
>>>>   * kvm_vgic_map_resources - Configure global VGIC state before running any VCPUs
>>>>   * @kvm: pointer to the kvm struct
>>>>   *
>>>> @@ -566,6 +577,7 @@ void vgic_v2_init_emulation(struct kvm *kvm)
>>>>  	dist->vm_ops.add_sgi_source = vgic_v2_add_sgi_source;
>>>>  	dist->vm_ops.init_model = vgic_v2_init_model;
>>>>  	dist->vm_ops.map_resources = vgic_v2_map_resources;
>>>> +	dist->vm_ops.inject_msi = vgic_v2m_inject_msi;
>>>>  
>>>>  	kvm->arch.max_vcpus = VGIC_V2_MAX_CPUS;
>>>>  }
>>>>
>>>
>>
>