Re: [PATCH 08/10] KVM: arm/arm64: vgic: Handle unshared mapped interrupts

[Auger Eric <eric.auger@redhat.com>]

Hi Marc,

On 25/05/2017 21:14, Marc Zyngier wrote:
> On Wed, May 24 2017 at 10:13:21 pm BST, Eric Auger <eric.auger@redhat.com> wrote:
>> Virtual interrupts directly mapped to physical interrupts require
>> some special care. Their pending and active state must be observed
>> at distributor level and not in the list register.
>>
>> Also a level sensitive interrupt's level is not toggled down by any
>> maintenance IRQ handler as the EOI is not trapped.
>>
>> This patch adds an host_irq field in vgic_irq struct to easily
>> get the irqchip state of the host irq. We also handle the
>> physical IRQ case in vgic_validate_injection and add helpers to
>> get the line level and active state.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> ---
>>  include/kvm/arm_vgic.h    |  4 +++-
>>  virt/kvm/arm/arch_timer.c |  3 ++-
>>  virt/kvm/arm/vgic/vgic.c  | 44 ++++++++++++++++++++++++++++++++++++++------
>>  virt/kvm/arm/vgic/vgic.h  |  9 ++++++++-
>>  4 files changed, 51 insertions(+), 9 deletions(-)
>>
>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>> index ef71858..695ebc7 100644
>> --- a/include/kvm/arm_vgic.h
>> +++ b/include/kvm/arm_vgic.h
>> @@ -112,6 +112,7 @@ struct vgic_irq {
>>  	bool hw;			/* Tied to HW IRQ */
>>  	struct kref refcount;		/* Used for LPIs */
>>  	u32 hwintid;			/* HW INTID number */
>> +	unsigned int host_irq;		/* linux irq corresponding to hwintid */
>>  	union {
>>  		u8 targets;			/* GICv2 target VCPUs mask */
>>  		u32 mpidr;			/* GICv3 target VCPU */
>> @@ -301,7 +302,8 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>>  			bool level);
>>  int kvm_vgic_inject_mapped_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>>  			       bool level);
>> -int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq);
>> +int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
>> +			  u32 virt_irq, u32 phys_irq);
>>  int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int virt_irq);
>>  bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq);
>>  
>> diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
>> index 5976609..45f4779 100644
>> --- a/virt/kvm/arm/arch_timer.c
>> +++ b/virt/kvm/arm/arch_timer.c
>> @@ -651,7 +651,8 @@ int kvm_timer_enable(struct kvm_vcpu *vcpu)
>>  	 * Tell the VGIC that the virtual interrupt is tied to a
>>  	 * physical interrupt. We do that once per VCPU.
>>  	 */
>> -	ret = kvm_vgic_map_phys_irq(vcpu, vtimer->irq.irq, phys_irq);
>> +	ret = kvm_vgic_map_phys_irq(vcpu, host_vtimer_irq,
>> +				    vtimer->irq.irq, phys_irq);
>>  	if (ret)
>>  		return ret;
>>  
>> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
>> index 83b24d2..aa0618c 100644
>> --- a/virt/kvm/arm/vgic/vgic.c
>> +++ b/virt/kvm/arm/vgic/vgic.c
>> @@ -137,6 +137,28 @@ void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq)
>>  	kfree(irq);
>>  }
>>  
>> +bool irq_line_level(struct vgic_irq *irq)
>> +{
>> +	bool line_level = irq->line_level;
>> +
>> +	if (unlikely(is_unshared_mapped(irq)))
> 
> The "unshared" bit doesn't mean much to me. Do you want to say "an
> interrupt that belongs to a device only accessed by a single VM"?

Yes. This was the former naming. timer used shared HW irq and others
were dubberd unshared (https://lkml.org/lkml/2015/11/19/362).
> 
> Given that this can only be an SPI, can we use something like
> "is_mapped_spi()" instead? I find it a lot more readable, but I'm open
> to alternative suggestions.
Yep!

Thanks

Eric
> 
>> +		WARN_ON(irq_get_irqchip_state(irq->host_irq,
>> +					      IRQCHIP_STATE_PENDING,
>> +					      &line_level));
>> +	return line_level;
>> +}
>> +
>> +bool irq_is_active(struct vgic_irq *irq)
>> +{
>> +	bool is_active = irq->active;
>> +
>> +	if (unlikely(is_unshared_mapped(irq)))
>> +		WARN_ON(irq_get_irqchip_state(irq->host_irq,
>> +					      IRQCHIP_STATE_ACTIVE,
>> +					      &is_active));
>> +	return is_active;
>> +}
>> +
>>  /**
>>   * kvm_vgic_target_oracle - compute the target vcpu for an irq
>>   *
>> @@ -153,7 +175,7 @@ static struct kvm_vcpu *vgic_target_oracle(struct vgic_irq *irq)
>>  	DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
>>  
>>  	/* If the interrupt is active, it must stay on the current vcpu */
>> -	if (irq->active)
>> +	if (irq_is_active(irq))
>>  		return irq->vcpu ? : irq->target_vcpu;
>>  
>>  	/*
>> @@ -195,14 +217,18 @@ static int vgic_irq_cmp(void *priv, struct list_head *a, struct list_head *b)
>>  {
>>  	struct vgic_irq *irqa = container_of(a, struct vgic_irq, ap_list);
>>  	struct vgic_irq *irqb = container_of(b, struct vgic_irq, ap_list);
>> +	bool activea, activeb;
>>  	bool penda, pendb;
>>  	int ret;
>>  
>>  	spin_lock(&irqa->irq_lock);
>>  	spin_lock_nested(&irqb->irq_lock, SINGLE_DEPTH_NESTING);
>>  
>> -	if (irqa->active || irqb->active) {
>> -		ret = (int)irqb->active - (int)irqa->active;
>> +	activea = irq_is_active(irqa);
>> +	activeb = irq_is_active(irqb);
>> +
>> +	if (activea || activeb) {
>> +		ret = (int)activeb - (int)activea;
>>  		goto out;
>>  	}
>>  
>> @@ -234,13 +260,17 @@ static void vgic_sort_ap_list(struct kvm_vcpu *vcpu)
>>  
>>  /*
>>   * Only valid injection if changing level for level-triggered IRQs or for a
>> - * rising edge.
>> + * rising edge. Injection of virtual interrupts associated to physical
>> + * interrupts always is valid.
>>   */
>>  static bool vgic_validate_injection(struct vgic_irq *irq, bool level)
>>  {
>>  	switch (irq->config) {
>>  	case VGIC_CONFIG_LEVEL:
>> -		return irq->line_level != level;
>> +		if (unlikely(is_unshared_mapped(irq)))
>> +			return true;
>> +		else
>> +			return irq->line_level != level;
> 
> This would be more readable as:
> 
> 		return (irq->line_level != level ||
>                 	unlikely(is_unshared_mapped(irq)));

OK

Thanks

Eric
> 
>>  	case VGIC_CONFIG_EDGE:
>>  		return level;
>>  	}
>> @@ -392,7 +422,8 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>>  	return 0;
>>  }
>>  
>> -int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
>> +int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, unsigned int host_irq,
>> +			  u32 virt_irq, u32 phys_irq)
>>  {
>>  	struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
>>  
>> @@ -402,6 +433,7 @@ int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
>>  
>>  	irq->hw = true;
>>  	irq->hwintid = phys_irq;
>> +	irq->host_irq = host_irq;
> 
> If you're now passing the Linux IRQ to the mapping function, you might
> as well move the code that extracts the host hwirq here as well.
> 
>>  
>>  	spin_unlock(&irq->irq_lock);
>>  	vgic_put_irq(vcpu->kvm, irq);
>> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
>> index da83e4c..dc4972b 100644
>> --- a/virt/kvm/arm/vgic/vgic.h
>> +++ b/virt/kvm/arm/vgic/vgic.h
>> @@ -17,6 +17,7 @@
>>  #define __KVM_ARM_VGIC_NEW_H__
>>  
>>  #include <linux/irqchip/arm-gic-common.h>
>> +#include <linux/interrupt.h>
>>  
>>  #define PRODUCT_ID_KVM		0x4b	/* ASCII code K */
>>  #define IMPLEMENTER_ARM		0x43b
>> @@ -96,14 +97,20 @@
>>  /* we only support 64 kB translation table page size */
>>  #define KVM_ITS_L1E_ADDR_MASK		GENMASK_ULL(51, 16)
>>  
>> +bool irq_line_level(struct vgic_irq *irq);
>> +bool irq_is_active(struct vgic_irq *irq);
>> +
>>  static inline bool irq_is_pending(struct vgic_irq *irq)
>>  {
>>  	if (irq->config == VGIC_CONFIG_EDGE)
>>  		return irq->pending_latch;
>>  	else
>> -		return irq->pending_latch || irq->line_level;
>> +		return irq->pending_latch || irq_line_level(irq);
>>  }
>>  
>> +#define is_unshared_mapped(i) \
>> +((i)->hw && (i)->intid >= VGIC_NR_PRIVATE_IRQS && (i)->intid < 1020)
>> +
>>  /*
>>   * This struct provides an intermediate representation of the fields contained
>>   * in the GICH_VMCR and ICH_VMCR registers, such that code exporting the GIC
> 
> Thanks,
> 
> 	M.
>