Subject: [PATCH v3 18/19] arm/arm64: KVM: enable kernel side of GICv3 emulation

From: [email-masked] (Andre Przywara)
Date: Mon, 10 Nov 2014 12:19:09 +0000

Hej Christoffer,

On 07/11/14 16:07, Christoffer Dall wrote:
> On Fri, Oct 31, 2014 at 05:26:53PM +0000, Andre Przywara wrote:
>> With all the necessary GICv3 emulation code in place, we can now
>> connect the code to the GICv3 backend in the kernel.
>> The LR register handling is different depending on the emulated GIC
>> model, so provide different implementations for each.
>> Also allow non-v2-compatible GICv3 implementations (which don't
>> provide MMIO regions for the virtual CPU interface in the DT), but
>> restrict those hosts to use GICv3 guests only.
> 
> s/use/support/
> 
>>
>> Signed-off-by: Andre Przywara <[email-masked]>
>> ---
>>  virt/kvm/arm/vgic-v3.c |  168 ++++++++++++++++++++++++++++++++++++------------
>>  virt/kvm/arm/vgic.c    |    4 ++
>>  2 files changed, 130 insertions(+), 42 deletions(-)
>>
>> diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c
>> index ce50918..c0e901c 100644
>> --- a/virt/kvm/arm/vgic-v3.c
>> +++ b/virt/kvm/arm/vgic-v3.c
>> @@ -34,6 +34,7 @@
>>  #define GICH_LR_VIRTUALID		(0x3ffUL << 0)
>>  #define GICH_LR_PHYSID_CPUID_SHIFT	(10)
>>  #define GICH_LR_PHYSID_CPUID		(7UL << GICH_LR_PHYSID_CPUID_SHIFT)
>> +#define ICH_LR_VIRTUALID_MASK		(BIT_ULL(32) - 1)
>>  
>>  /*
>>   * LRs are stored in reverse order in memory. make sure we index them
>> @@ -43,7 +44,35 @@
>>  
>>  static u32 ich_vtr_el2;
>>  
>> -static struct vgic_lr vgic_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
>> +static u64 sync_lr_val(u8 state)
> 
> is this lr_state_to_val ?
> 
>> +{
>> +	u64 lr_val = 0;
>> +
>> +	if (state & LR_STATE_PENDING)
>> +		lr_val |= ICH_LR_PENDING_BIT;
>> +	if (state & LR_STATE_ACTIVE)
>> +		lr_val |= ICH_LR_ACTIVE_BIT;
>> +	if (state & LR_EOI_INT)
>> +		lr_val |= ICH_LR_EOI;
>> +
>> +	return lr_val;
>> +}
>> +
>> +static u8 sync_lr_state(u64 lr_val)
> 
> and lr_val_to_state ?
> 
> at least these sync names don't make much sense to me...
> 
>> +{
>> +	u8 state = 0;
>> +
>> +	if (lr_val & ICH_LR_PENDING_BIT)
>> +		state |= LR_STATE_PENDING;
>> +	if (lr_val & ICH_LR_ACTIVE_BIT)
>> +		state |= LR_STATE_ACTIVE;
>> +	if (lr_val & ICH_LR_EOI)
>> +		state |= LR_EOI_INT;
>> +
>> +	return state;
>> +}
>> +
>> +static struct vgic_lr vgic_v2_on_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
>>  {
>>  	struct vgic_lr lr_desc;
>>  	u64 val = vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)];
>> @@ -53,30 +82,53 @@ static struct vgic_lr vgic_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
>>  		lr_desc.source	= (val >> GICH_LR_PHYSID_CPUID_SHIFT) & 0x7;
>>  	else
>>  		lr_desc.source = 0;
>> -	lr_desc.state	= 0;
>> +	lr_desc.state	= sync_lr_state(val);
>>  
>> -	if (val & ICH_LR_PENDING_BIT)
>> -		lr_desc.state |= LR_STATE_PENDING;
>> -	if (val & ICH_LR_ACTIVE_BIT)
>> -		lr_desc.state |= LR_STATE_ACTIVE;
>> -	if (val & ICH_LR_EOI)
>> -		lr_desc.state |= LR_EOI_INT;
>> +	return lr_desc;
>> +}
>> +
>> +static struct vgic_lr vgic_v3_on_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
>> +{
>> +	struct vgic_lr lr_desc;
>> +	u64 val = vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)];
>> +
>> +	lr_desc.irq	= val & ICH_LR_VIRTUALID_MASK;
>> +	lr_desc.source	= 0;
>> +	lr_desc.state	= sync_lr_state(val);
>>  
>>  	return lr_desc;
>>  }
>>  
>> -static void vgic_v3_set_lr(struct kvm_vcpu *vcpu, int lr,
>> -			   struct vgic_lr lr_desc)
>> +static void vgic_v3_on_v3_set_lr(struct kvm_vcpu *vcpu, int lr,
>> +				 struct vgic_lr lr_desc)
>>  {
>> -	u64 lr_val = (((u32)lr_desc.source << GICH_LR_PHYSID_CPUID_SHIFT) |
>> -		      lr_desc.irq);
>> +	u64 lr_val;
>>  
>> -	if (lr_desc.state & LR_STATE_PENDING)
>> -		lr_val |= ICH_LR_PENDING_BIT;
>> -	if (lr_desc.state & LR_STATE_ACTIVE)
>> -		lr_val |= ICH_LR_ACTIVE_BIT;
>> -	if (lr_desc.state & LR_EOI_INT)
>> -		lr_val |= ICH_LR_EOI;
>> +	lr_val = lr_desc.irq;
>> +
>> +	/*
>> +	 * currently all guest IRQs are Group1, as Group0 would result
> 
> Can you guess my comment here?
> 
>> +	 * in a FIQ in the guest, which it wouldn't expect.
>> +	 * Eventually we want to make this configurable, so we may revisit
>> +	 * this in the future.
>> +	 */
>> +	lr_val |= ICH_LR_GROUP;
>> +
>> +	lr_val |= sync_lr_val(lr_desc.state);
>> +
>> +	vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)] = lr_val;
>> +}
>> +
>> +static void vgic_v2_on_v3_set_lr(struct kvm_vcpu *vcpu, int lr,
>> +				 struct vgic_lr lr_desc)
>> +{
>> +	u64 lr_val;
>> +
>> +	lr_val = lr_desc.irq;
>> +
>> +	lr_val |= (u32)lr_desc.source << GICH_LR_PHYSID_CPUID_SHIFT;
>> +
>> +	lr_val |= sync_lr_val(lr_desc.state);
>>  
>>  	vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[LR_INDEX(lr)] = lr_val;
>>  }
>> @@ -145,9 +197,8 @@ static void vgic_v3_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
>>  
>>  static void vgic_v3_enable(struct kvm_vcpu *vcpu)
>>  {
>> -	struct vgic_v3_cpu_if *vgic_v3;
>> +	struct vgic_v3_cpu_if *vgic_v3 = &vcpu->arch.vgic_cpu.vgic_v3;
>>  
>> -	vgic_v3 = &vcpu->arch.vgic_cpu.vgic_v3;
> 
> unnecessary change?
> 
>>  	/*
>>  	 * By forcing VMCR to zero, the GIC will restore the binary
>>  	 * points to their reset values. Anything else resets to zero

So most of the code above is gone now in this form due to the drop of
init_emul and friends I did earlier last week due to your comments.
So I will skip those comments for now (or better: try to translate them
to the new code structure if possbile) and eagerly wait for them to
reappear in a different form in the v4 comments ;-)

>> @@ -155,7 +206,14 @@ static void vgic_v3_enable(struct kvm_vcpu *vcpu)
>>  	 */
>>  	vgic_v3->vgic_vmcr = 0;
>>  
>> -	vgic_v3->vgic_sre = 0;
>> +	/*
>> +	 * Set the SRE_EL1 value depending on the configured
>> +	 * emulated vGIC model.
>> +	 */
>> +	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
>> +		vgic_v3->vgic_sre = ICC_SRE_EL1_SRE;
> 
> If we're on hardware with the GICv2 backwards compatibility can the
> guest not actually set ICC_SRE_EL1_SRE to 0 but then we are not
> preserving this because we wouldn't be trapping such accesses anymore?
> 
> Also, this is really about the reset value of that field, which the
> comment above is not being specific about.
> 
> Further, that would mean that the field is NOT actually RAO/WI, and thus
> the spec dictates that the field should reset to zero if EL1 is the
> highest implemented exception level and the field is not RAO/WI, which
> is what the guest expects, no?

I am still thinking about this (because it is probably true). Need to
discuss with Marc what we can do about this.

Thanks,
Andre.

> 
>> +	else
>> +		vgic_v3->vgic_sre = 0;
>>  
>>  	/* Get the show on the road... */
>>  	vgic_v3->vgic_hcr = ICH_HCR_EN;
>> @@ -173,6 +231,15 @@ static const struct vgic_ops vgic_v3_ops = {
>>  	.enable			= vgic_v3_enable,
>>  };
>>  
>> +static void init_vgic_v3_emul(struct kvm *kvm)
>> +{
>> +	struct vgic_vm_ops *vm_ops = &kvm->arch.vgic.vm_ops;
>> +
>> +	vm_ops->get_lr = vgic_v3_on_v3_get_lr;
>> +	vm_ops->set_lr = vgic_v3_on_v3_set_lr;
>> +	kvm->arch.max_vcpus = KVM_MAX_VCPUS;
>> +}
> 
> why do you need this indirection?  Just move vgic_v3_init_emul() up here
> and call that?
> 
>> +
>>  static bool vgic_v3_init_emul_compat(struct kvm *kvm, int type)
>>  {
>>  	struct vgic_vm_ops *vm_ops = &kvm->arch.vgic.vm_ops;
>> @@ -186,14 +253,28 @@ static bool vgic_v3_init_emul_compat(struct kvm *kvm, int type)
>>  			return false;
>>  		}
>>  
>> -		vm_ops->get_lr = vgic_v3_get_lr;
>> -		vm_ops->set_lr = vgic_v3_set_lr;
>> +		vm_ops->get_lr = vgic_v2_on_v3_get_lr;
>> +		vm_ops->set_lr = vgic_v2_on_v3_set_lr;
>>  		kvm->arch.max_vcpus = 8;
>>  		return true;
>> +	case KVM_DEV_TYPE_ARM_VGIC_V3:
>> +		init_vgic_v3_emul(kvm);
>> +		return true;
>>  	}
>>  	return false;
>>  }
>>  
>> +static bool vgic_v3_init_emul(struct kvm *kvm, int type)
>> +{
>> +	switch (type) {
>> +	case KVM_DEV_TYPE_ARM_VGIC_V3:
>> +		init_vgic_v3_emul(kvm);
>> +		return true;
>> +	}
>> +
>> +	return false;
>> +}
>> +
>>  static struct vgic_params vgic_v3_params;
>>  
>>  /**
>> @@ -235,29 +316,32 @@ int vgic_v3_probe(struct device_node *vgic_node,
>>  
>>  	gicv_idx += 3; /* Also skip GICD, GICC, GICH */
>>  	if (of_address_to_resource(vgic_node, gicv_idx, &vcpu_res)) {
>> -		kvm_err("Cannot obtain GICV region\n");
>> -		ret = -ENXIO;
>> -		goto out;
>> -	}
>> +		kvm_info("GICv3: GICv2 emulation not available\n");
>> +		vgic->vcpu_base = 0;
>> +		vgic->init_emul = vgic_v3_init_emul;
>> +	} else {
>> +		if (!PAGE_ALIGNED(vcpu_res.start)) {
>> +			kvm_err("GICV physical address 0x%llx not page aligned\n",
>> +				(unsigned long long)vcpu_res.start);
>> +			ret = -ENXIO;
>> +			goto out;
>> +		}
>>  
>> -	if (!PAGE_ALIGNED(vcpu_res.start)) {
>> -		kvm_err("GICV physical address 0x%llx not page aligned\n",
>> -			(unsigned long long)vcpu_res.start);
>> -		ret = -ENXIO;
>> -		goto out;
>> -	}
>> +		if (!PAGE_ALIGNED(resource_size(&vcpu_res))) {
>> +			kvm_err("GICV size 0x%llx not a multiple of page size 0x%lx\n",
>> +				(unsigned long long)resource_size(&vcpu_res),
>> +				PAGE_SIZE);
>> +			ret = -ENXIO;
>> +			goto out;
>> +		}
>>  
>> -	if (!PAGE_ALIGNED(resource_size(&vcpu_res))) {
>> -		kvm_err("GICV size 0x%llx not a multiple of page size 0x%lx\n",
>> -			(unsigned long long)resource_size(&vcpu_res),
>> -			PAGE_SIZE);
>> -		ret = -ENXIO;
>> -		goto out;
>> +		vgic->vcpu_base = vcpu_res.start;
>> +		vgic->init_emul = vgic_v3_init_emul_compat;
>> +		kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>> +					KVM_DEV_TYPE_ARM_VGIC_V2);
>>  	}
>> -	kvm_register_device_ops(&kvm_arm_vgic_v2_ops, KVM_DEV_TYPE_ARM_VGIC_V2);
>> +	kvm_register_device_ops(&kvm_arm_vgic_v3_ops, KVM_DEV_TYPE_ARM_VGIC_V3);
>>  
>> -	vgic->init_emul = vgic_v3_init_emul_compat;
>> -	vgic->vcpu_base = vcpu_res.start;
>>  	vgic->vctrl_base = NULL;
>>  	vgic->type = VGIC_V3;
>>  
>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>> index 2867269d..16d7c9d 100644
>> --- a/virt/kvm/arm/vgic.c
>> +++ b/virt/kvm/arm/vgic.c
>> @@ -1542,6 +1542,10 @@ static bool init_emulation_ops(struct kvm *kvm, int type)
>>  	switch (type) {
>>  	case KVM_DEV_TYPE_ARM_VGIC_V2:
>>  		return vgic_v2_init_emulation_ops(kvm, type);
>> +#ifdef CONFIG_ARM_GIC_V3
>> +	case KVM_DEV_TYPE_ARM_VGIC_V3:
>> +		return vgic_v3_init_emulation_ops(kvm, type);
> 
> needs Documentation
> 
>> +#endif
>>  	}
>>  	return false;
>>  }
>> -- 
>> 1.7.9.5
>>
>