Re: [PATCH v3 05/20] KVM: arm/arm64: Support calling vgic_update_irq_pending from irq context

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

On 23/09/17 01:41, Christoffer Dall wrote:
> We are about to optimize our timer handling logic which involves
> injecting irqs to the vgic directly from the irq handler.
> 
> Unfortunately, the injection path can take any AP list lock and irq lock
> and we must therefore make sure to use spin_lock_irqsave where ever
> interrupts are enabled and we are taking any of those locks, to avoid
> deadlocking between process context and the ISR.
> 
> This changes a lot of the VGIC code, but The good news are that the
> changes are mostly mechanical.
> 
> Signed-off-by: Christoffer Dall <cdall@linaro.org>
> ---
>  virt/kvm/arm/vgic/vgic-its.c     | 17 +++++++-----
>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 22 +++++++++------
>  virt/kvm/arm/vgic/vgic-mmio-v3.c | 17 +++++++-----
>  virt/kvm/arm/vgic/vgic-mmio.c    | 44 +++++++++++++++++------------
>  virt/kvm/arm/vgic/vgic-v2.c      |  5 ++--
>  virt/kvm/arm/vgic/vgic-v3.c      | 12 ++++----
>  virt/kvm/arm/vgic/vgic.c         | 60 +++++++++++++++++++++++++---------------
>  virt/kvm/arm/vgic/vgic.h         |  3 +-
>  8 files changed, 108 insertions(+), 72 deletions(-)
> 
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index f51c1e1..9f5e347 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -278,6 +278,7 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
>  	u64 propbase = GICR_PROPBASER_ADDRESS(kvm->arch.vgic.propbaser);
>  	u8 prop;
>  	int ret;
> +	unsigned long flags;
>  
>  	ret = kvm_read_guest(kvm, propbase + irq->intid - GIC_LPI_OFFSET,
>  			     &prop, 1);
> @@ -285,15 +286,15 @@ static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
>  	if (ret)
>  		return ret;
>  
> -	spin_lock(&irq->irq_lock);
> +	spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  	if (!filter_vcpu || filter_vcpu == irq->target_vcpu) {
>  		irq->priority = LPI_PROP_PRIORITY(prop);
>  		irq->enabled = LPI_PROP_ENABLE_BIT(prop);
>  
> -		vgic_queue_irq_unlock(kvm, irq);
> +		vgic_queue_irq_unlock(kvm, irq, flags);
>  	} else {
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  	}
>  
>  	return 0;
> @@ -393,6 +394,7 @@ static int its_sync_lpi_pending_table(struct kvm_vcpu *vcpu)
>  	int ret = 0;
>  	u32 *intids;
>  	int nr_irqs, i;
> +	unsigned long flags;
>  
>  	nr_irqs = vgic_copy_lpi_list(vcpu, &intids);
>  	if (nr_irqs < 0)
> @@ -420,9 +422,9 @@ static int its_sync_lpi_pending_table(struct kvm_vcpu *vcpu)
>  		}
>  
>  		irq = vgic_get_irq(vcpu->kvm, NULL, intids[i]);
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		irq->pending_latch = pendmask & (1U << bit_nr);
> -		vgic_queue_irq_unlock(vcpu->kvm, irq);
> +		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  
> @@ -515,6 +517,7 @@ static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
>  {
>  	struct kvm_vcpu *vcpu;
>  	struct its_ite *ite;
> +	unsigned long flags;
>  
>  	if (!its->enabled)
>  		return -EBUSY;
> @@ -530,9 +533,9 @@ static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
>  	if (!vcpu->arch.vgic_cpu.lpis_enabled)
>  		return -EBUSY;
>  
> -	spin_lock(&ite->irq->irq_lock);
> +	spin_lock_irqsave(&ite->irq->irq_lock, flags);
>  	ite->irq->pending_latch = true;
> -	vgic_queue_irq_unlock(kvm, ite->irq);
> +	vgic_queue_irq_unlock(kvm, ite->irq, flags);
>  
>  	return 0;
>  }
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> index b3d4a10..e21e2f4 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> @@ -74,6 +74,7 @@ static void vgic_mmio_write_sgir(struct kvm_vcpu *source_vcpu,
>  	int mode = (val >> 24) & 0x03;
>  	int c;
>  	struct kvm_vcpu *vcpu;
> +	unsigned long flags;
>  
>  	switch (mode) {
>  	case 0x0:		/* as specified by targets */
> @@ -97,11 +98,11 @@ static void vgic_mmio_write_sgir(struct kvm_vcpu *source_vcpu,
>  
>  		irq = vgic_get_irq(source_vcpu->kvm, vcpu, intid);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		irq->pending_latch = true;
>  		irq->source |= 1U << source_vcpu->vcpu_id;
>  
> -		vgic_queue_irq_unlock(source_vcpu->kvm, irq);
> +		vgic_queue_irq_unlock(source_vcpu->kvm, irq, flags);
>  		vgic_put_irq(source_vcpu->kvm, irq);
>  	}
>  }
> @@ -131,6 +132,7 @@ static void vgic_mmio_write_target(struct kvm_vcpu *vcpu,
>  	u32 intid = VGIC_ADDR_TO_INTID(addr, 8);
>  	u8 cpu_mask = GENMASK(atomic_read(&vcpu->kvm->online_vcpus) - 1, 0);
>  	int i;
> +	unsigned long flags;
>  
>  	/* GICD_ITARGETSR[0-7] are read-only */
>  	if (intid < VGIC_NR_PRIVATE_IRQS)
> @@ -140,13 +142,13 @@ static void vgic_mmio_write_target(struct kvm_vcpu *vcpu,
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, NULL, intid + i);
>  		int target;
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  		irq->targets = (val >> (i * 8)) & cpu_mask;
>  		target = irq->targets ? __ffs(irq->targets) : 0;
>  		irq->target_vcpu = kvm_get_vcpu(vcpu->kvm, target);
>  
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  }
> @@ -174,17 +176,18 @@ static void vgic_mmio_write_sgipendc(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = addr & 0x0f;
>  	int i;
> +	unsigned long flags;
>  
>  	for (i = 0; i < len; i++) {
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  		irq->source &= ~((val >> (i * 8)) & 0xff);
>  		if (!irq->source)
>  			irq->pending_latch = false;
>  
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  }
> @@ -195,19 +198,20 @@ static void vgic_mmio_write_sgipends(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = addr & 0x0f;
>  	int i;
> +	unsigned long flags;
>  
>  	for (i = 0; i < len; i++) {
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  		irq->source |= (val >> (i * 8)) & 0xff;
>  
>  		if (irq->source) {
>  			irq->pending_latch = true;
> -			vgic_queue_irq_unlock(vcpu->kvm, irq);
> +			vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  		} else {
> -			spin_unlock(&irq->irq_lock);
> +			spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		}
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> index 408ef06..8378610 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
> @@ -129,6 +129,7 @@ static void vgic_mmio_write_irouter(struct kvm_vcpu *vcpu,
>  {
>  	int intid = VGIC_ADDR_TO_INTID(addr, 64);
>  	struct vgic_irq *irq;
> +	unsigned long flags;
>  
>  	/* The upper word is WI for us since we don't implement Aff3. */
>  	if (addr & 4)
> @@ -139,13 +140,13 @@ static void vgic_mmio_write_irouter(struct kvm_vcpu *vcpu,
>  	if (!irq)
>  		return;
>  
> -	spin_lock(&irq->irq_lock);
> +	spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  	/* We only care about and preserve Aff0, Aff1 and Aff2. */
>  	irq->mpidr = val & GENMASK(23, 0);
>  	irq->target_vcpu = kvm_mpidr_to_vcpu(vcpu->kvm, irq->mpidr);
>  
> -	spin_unlock(&irq->irq_lock);
> +	spin_unlock_irqrestore(&irq->irq_lock, flags);
>  	vgic_put_irq(vcpu->kvm, irq);
>  }
>  
> @@ -241,11 +242,12 @@ static void vgic_v3_uaccess_write_pending(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
>  	int i;
> +	unsigned long flags;
>  
>  	for (i = 0; i < len * 8; i++) {
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		if (test_bit(i, &val)) {
>  			/*
>  			 * pending_latch is set irrespective of irq type
> @@ -253,10 +255,10 @@ static void vgic_v3_uaccess_write_pending(struct kvm_vcpu *vcpu,
>  			 * restore irq config before pending info.
>  			 */
>  			irq->pending_latch = true;
> -			vgic_queue_irq_unlock(vcpu->kvm, irq);
> +			vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  		} else {
>  			irq->pending_latch = false;
> -			spin_unlock(&irq->irq_lock);
> +			spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		}
>  
>  		vgic_put_irq(vcpu->kvm, irq);
> @@ -799,6 +801,7 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg)
>  	int sgi, c;
>  	int vcpu_id = vcpu->vcpu_id;
>  	bool broadcast;
> +	unsigned long flags;
>  
>  	sgi = (reg & ICC_SGI1R_SGI_ID_MASK) >> ICC_SGI1R_SGI_ID_SHIFT;
>  	broadcast = reg & BIT_ULL(ICC_SGI1R_IRQ_ROUTING_MODE_BIT);
> @@ -837,10 +840,10 @@ void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg)
>  
>  		irq = vgic_get_irq(vcpu->kvm, c_vcpu, sgi);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		irq->pending_latch = true;
>  
> -		vgic_queue_irq_unlock(vcpu->kvm, irq);
> +		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  }
> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
> index c1e4bdd..deb51ee 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
> @@ -69,13 +69,14 @@ void vgic_mmio_write_senable(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
>  	int i;
> +	unsigned long flags;
>  
>  	for_each_set_bit(i, &val, len * 8) {
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		irq->enabled = true;
> -		vgic_queue_irq_unlock(vcpu->kvm, irq);
> +		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
> @@ -87,15 +88,16 @@ void vgic_mmio_write_cenable(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
>  	int i;
> +	unsigned long flags;
>  
>  	for_each_set_bit(i, &val, len * 8) {
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  		irq->enabled = false;
>  
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  }
> @@ -126,14 +128,15 @@ void vgic_mmio_write_spending(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
>  	int i;
> +	unsigned long flags;
>  
>  	for_each_set_bit(i, &val, len * 8) {
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		irq->pending_latch = true;
>  
> -		vgic_queue_irq_unlock(vcpu->kvm, irq);
> +		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  }
> @@ -144,15 +147,16 @@ void vgic_mmio_write_cpending(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
>  	int i;
> +	unsigned long flags;
>  
>  	for_each_set_bit(i, &val, len * 8) {
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  		irq->pending_latch = false;
>  
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  }
> @@ -181,7 +185,8 @@ static void vgic_mmio_change_active(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
>  				    bool new_active_state)
>  {
>  	struct kvm_vcpu *requester_vcpu;
> -	spin_lock(&irq->irq_lock);
> +	unsigned long flags;
> +	spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  	/*
>  	 * The vcpu parameter here can mean multiple things depending on how
> @@ -216,9 +221,9 @@ static void vgic_mmio_change_active(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
>  
>  	irq->active = new_active_state;
>  	if (new_active_state)
> -		vgic_queue_irq_unlock(vcpu->kvm, irq);
> +		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  	else
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  }
>  
>  /*
> @@ -352,14 +357,15 @@ void vgic_mmio_write_priority(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = VGIC_ADDR_TO_INTID(addr, 8);
>  	int i;
> +	unsigned long flags;
>  
>  	for (i = 0; i < len; i++) {
>  		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		/* Narrow the priority range to what we actually support */
>  		irq->priority = (val >> (i * 8)) & GENMASK(7, 8 - VGIC_PRI_BITS);
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
> @@ -390,6 +396,7 @@ void vgic_mmio_write_config(struct kvm_vcpu *vcpu,
>  {
>  	u32 intid = VGIC_ADDR_TO_INTID(addr, 2);
>  	int i;
> +	unsigned long flags;
>  
>  	for (i = 0; i < len * 4; i++) {
>  		struct vgic_irq *irq;
> @@ -404,14 +411,14 @@ void vgic_mmio_write_config(struct kvm_vcpu *vcpu,
>  			continue;
>  
>  		irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  		if (test_bit(i * 2 + 1, &val))
>  			irq->config = VGIC_CONFIG_EDGE;
>  		else
>  			irq->config = VGIC_CONFIG_LEVEL;
>  
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  }
> @@ -443,6 +450,7 @@ void vgic_write_irq_line_level_info(struct kvm_vcpu *vcpu, u32 intid,
>  {
>  	int i;
>  	int nr_irqs = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
> +	unsigned long flags;
>  
>  	for (i = 0; i < 32; i++) {
>  		struct vgic_irq *irq;
> @@ -459,12 +467,12 @@ void vgic_write_irq_line_level_info(struct kvm_vcpu *vcpu, u32 intid,
>  		 * restore irq config before line level.
>  		 */
>  		new_level = !!(val & (1U << i));
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		irq->line_level = new_level;
>  		if (new_level)
> -			vgic_queue_irq_unlock(vcpu->kvm, irq);
> +			vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  		else
> -			spin_unlock(&irq->irq_lock);
> +			spin_unlock_irqrestore(&irq->irq_lock, flags);
>  
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
> diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
> index e4187e5..8089710 100644
> --- a/virt/kvm/arm/vgic/vgic-v2.c
> +++ b/virt/kvm/arm/vgic/vgic-v2.c
> @@ -62,6 +62,7 @@ void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
>  	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>  	struct vgic_v2_cpu_if *cpuif = &vgic_cpu->vgic_v2;
>  	int lr;
> +	unsigned long flags;
>  
>  	cpuif->vgic_hcr &= ~GICH_HCR_UIE;
>  
> @@ -77,7 +78,7 @@ void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
>  
>  		irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  		/* Always preserve the active bit */
>  		irq->active = !!(val & GICH_LR_ACTIVE_BIT);
> @@ -104,7 +105,7 @@ void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
>  				irq->pending_latch = false;
>  		}
>  
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  
> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index 96ea597..863351c 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -44,6 +44,7 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
>  	struct vgic_v3_cpu_if *cpuif = &vgic_cpu->vgic_v3;
>  	u32 model = vcpu->kvm->arch.vgic.vgic_model;
>  	int lr;
> +	unsigned long flags;
>  
>  	cpuif->vgic_hcr &= ~ICH_HCR_UIE;
>  
> @@ -66,7 +67,7 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
>  		if (!irq)	/* An LPI could have been unmapped. */
>  			continue;
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  		/* Always preserve the active bit */
>  		irq->active = !!(val & ICH_LR_ACTIVE_BIT);
> @@ -94,7 +95,7 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
>  				irq->pending_latch = false;
>  		}
>  
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		vgic_put_irq(vcpu->kvm, irq);
>  	}
>  
> @@ -278,6 +279,7 @@ int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq)
>  	bool status;
>  	u8 val;
>  	int ret;
> +	unsigned long flags;
>  
>  retry:
>  	vcpu = irq->target_vcpu;
> @@ -296,13 +298,13 @@ int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq)
>  
>  	status = val & (1 << bit_nr);
>  
> -	spin_lock(&irq->irq_lock);
> +	spin_lock_irqsave(&irq->irq_lock, flags);
>  	if (irq->target_vcpu != vcpu) {
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		goto retry;
>  	}
>  	irq->pending_latch = status;
> -	vgic_queue_irq_unlock(vcpu->kvm, irq);
> +	vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
>  
>  	if (status) {
>  		/* clear consumed data */
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index e1f7dbc..b1bd238 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -53,6 +53,10 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = {
>   *   vcpuX->vcpu_id < vcpuY->vcpu_id:
>   *     spin_lock(vcpuX->arch.vgic_cpu.ap_list_lock);
>   *     spin_lock(vcpuY->arch.vgic_cpu.ap_list_lock);
> + *
> + * Since the VGIC must support injecting virtual interrupts from ISRs, we have
> + * to use the spin_lock_irqsave/spin_unlock_irqrestore versions of outer
> + * spinlocks for any lock that may be taken while injecting an interrupt.
>   */
>  
>  /*
> @@ -261,7 +265,8 @@ static bool vgic_validate_injection(struct vgic_irq *irq, bool level, void *owne
>   * Needs to be entered with the IRQ lock already held, but will return
>   * with all locks dropped.
>   */
> -bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
> +bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq,
> +			   unsigned long flags)
>  {
>  	struct kvm_vcpu *vcpu;
>  
> @@ -279,7 +284,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
>  		 * not need to be inserted into an ap_list and there is also
>  		 * no more work for us to do.
>  		 */
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  
>  		/*
>  		 * We have to kick the VCPU here, because we could be
> @@ -301,11 +306,11 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
>  	 * We must unlock the irq lock to take the ap_list_lock where
>  	 * we are going to insert this new pending interrupt.
>  	 */
> -	spin_unlock(&irq->irq_lock);
> +	spin_unlock_irqrestore(&irq->irq_lock, flags);
>  
>  	/* someone can do stuff here, which we re-check below */
>  
> -	spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
> +	spin_lock_irqsave(&vcpu->arch.vgic_cpu.ap_list_lock, flags);
>  	spin_lock(&irq->irq_lock);
>  
>  	/*
> @@ -322,9 +327,9 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
>  
>  	if (unlikely(irq->vcpu || vcpu != vgic_target_oracle(irq))) {
>  		spin_unlock(&irq->irq_lock);
> -		spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
> +		spin_unlock_irqrestore(&vcpu->arch.vgic_cpu.ap_list_lock, flags);
>  
> -		spin_lock(&irq->irq_lock);
> +		spin_lock_irqsave(&irq->irq_lock, flags);
>  		goto retry;
>  	}
>  
> @@ -337,7 +342,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
>  	irq->vcpu = vcpu;
>  
>  	spin_unlock(&irq->irq_lock);
> -	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
> +	spin_unlock_irqrestore(&vcpu->arch.vgic_cpu.ap_list_lock, flags);
>  
>  	kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
>  	kvm_vcpu_kick(vcpu);
> @@ -367,6 +372,7 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>  {
>  	struct kvm_vcpu *vcpu;
>  	struct vgic_irq *irq;
> +	unsigned long flags;
>  	int ret;
>  
>  	trace_vgic_update_irq_pending(cpuid, intid, level);
> @@ -383,11 +389,11 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>  	if (!irq)
>  		return -EINVAL;
>  
> -	spin_lock(&irq->irq_lock);
> +	spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  	if (!vgic_validate_injection(irq, level, owner)) {
>  		/* Nothing to see here, move along... */
> -		spin_unlock(&irq->irq_lock);
> +		spin_unlock_irqrestore(&irq->irq_lock, flags);
>  		vgic_put_irq(kvm, irq);
>  		return 0;
>  	}
> @@ -397,7 +403,7 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>  	else
>  		irq->pending_latch = true;
>  
> -	vgic_queue_irq_unlock(kvm, irq);
> +	vgic_queue_irq_unlock(kvm, irq, flags);
>  	vgic_put_irq(kvm, irq);
>  
>  	return 0;
> @@ -406,15 +412,16 @@ int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int intid,
>  int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
>  {
>  	struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
> +	unsigned long flags;
>  
>  	BUG_ON(!irq);
>  
> -	spin_lock(&irq->irq_lock);
> +	spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  	irq->hw = true;
>  	irq->hwintid = phys_irq;
>  
> -	spin_unlock(&irq->irq_lock);
> +	spin_unlock_irqrestore(&irq->irq_lock, flags);
>  	vgic_put_irq(vcpu->kvm, irq);
>  
>  	return 0;
> @@ -423,6 +430,7 @@ int kvm_vgic_map_phys_irq(struct kvm_vcpu *vcpu, u32 virt_irq, u32 phys_irq)
>  int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int virt_irq)
>  {
>  	struct vgic_irq *irq;
> +	unsigned long flags;
>  
>  	if (!vgic_initialized(vcpu->kvm))
>  		return -EAGAIN;
> @@ -430,12 +438,12 @@ int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int virt_irq)
>  	irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
>  	BUG_ON(!irq);
>  
> -	spin_lock(&irq->irq_lock);
> +	spin_lock_irqsave(&irq->irq_lock, flags);
>  
>  	irq->hw = false;
>  	irq->hwintid = 0;
>  
> -	spin_unlock(&irq->irq_lock);
> +	spin_unlock_irqrestore(&irq->irq_lock, flags);
>  	vgic_put_irq(vcpu->kvm, irq);
>  
>  	return 0;
> @@ -486,9 +494,10 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
>  {
>  	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>  	struct vgic_irq *irq, *tmp;
> +	unsigned long flags;
>  
>  retry:
> -	spin_lock(&vgic_cpu->ap_list_lock);
> +	spin_lock_irqsave(&vgic_cpu->ap_list_lock, flags);
>  
>  	list_for_each_entry_safe(irq, tmp, &vgic_cpu->ap_list_head, ap_list) {
>  		struct kvm_vcpu *target_vcpu, *vcpuA, *vcpuB;
> @@ -528,7 +537,7 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
>  		/* This interrupt looks like it has to be migrated. */
>  
>  		spin_unlock(&irq->irq_lock);
> -		spin_unlock(&vgic_cpu->ap_list_lock);
> +		spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
>  
>  		/*
>  		 * Ensure locking order by always locking the smallest
> @@ -542,7 +551,7 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
>  			vcpuB = vcpu;
>  		}
>  
> -		spin_lock(&vcpuA->arch.vgic_cpu.ap_list_lock);
> +		spin_lock_irqsave(&vcpuA->arch.vgic_cpu.ap_list_lock, flags);
>  		spin_lock_nested(&vcpuB->arch.vgic_cpu.ap_list_lock,
>  				 SINGLE_DEPTH_NESTING);
>  		spin_lock(&irq->irq_lock);
> @@ -566,11 +575,11 @@ static void vgic_prune_ap_list(struct kvm_vcpu *vcpu)
>  
>  		spin_unlock(&irq->irq_lock);
>  		spin_unlock(&vcpuB->arch.vgic_cpu.ap_list_lock);
> -		spin_unlock(&vcpuA->arch.vgic_cpu.ap_list_lock);
> +		spin_unlock_irqrestore(&vcpuA->arch.vgic_cpu.ap_list_lock, flags);
>  		goto retry;
>  	}
>  
> -	spin_unlock(&vgic_cpu->ap_list_lock);
> +	spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
>  }
>  
>  static inline void vgic_fold_lr_state(struct kvm_vcpu *vcpu)
> @@ -703,6 +712,8 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
>  	if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head))
>  		return;
>  
> +	DEBUG_SPINLOCK_BUG_ON(!irqs_disabled());
> +
>  	spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
>  	vgic_flush_lr_state(vcpu);
>  	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
> @@ -735,11 +746,12 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
>  	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>  	struct vgic_irq *irq;
>  	bool pending = false;
> +	unsigned long flags;
>  
>  	if (!vcpu->kvm->arch.vgic.enabled)
>  		return false;
>  
> -	spin_lock(&vgic_cpu->ap_list_lock);
> +	spin_lock_irqsave(&vgic_cpu->ap_list_lock, flags);
>  
>  	list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
>  		spin_lock(&irq->irq_lock);
> @@ -750,7 +762,7 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
>  			break;
>  	}
>  
> -	spin_unlock(&vgic_cpu->ap_list_lock);
> +	spin_unlock_irqrestore(&vgic_cpu->ap_list_lock, flags);
>  
>  	return pending;
>  }
> @@ -776,13 +788,15 @@ bool kvm_vgic_map_is_active(struct kvm_vcpu *vcpu, unsigned int virt_irq)
>  {
>  	struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, virt_irq);
>  	bool map_is_active;
> +	unsigned long flags;
>  
>  	if (!vgic_initialized(vcpu->kvm))
>  		return false;
> +	DEBUG_SPINLOCK_BUG_ON(!irqs_disabled());
>  
> -	spin_lock(&irq->irq_lock);
> +	spin_lock_irqsave(&irq->irq_lock, flags);

I'm a bit puzzled by this sequence: Either interrupts are disabled and
we don't need the irqsave version, or they aren't and the BUG_ON will
fire. kvm_vgic_map_is_active is called (indirectly) from
kvm_timer_flush_hwstate. And at this stage of the patches, we definitely
call this function with interrupts enabled.

Is it just a patch splitting snafu? Or something more serious? Same goes
for the DEBUG_SPINLOCK_BUG_ON in kvm_vgic_flush_hwstate.

>  	map_is_active = irq->hw && irq->active;
> -	spin_unlock(&irq->irq_lock);
> +	spin_unlock_irqrestore(&irq->irq_lock, flags);
>  	vgic_put_irq(vcpu->kvm, irq);
>  
>  	return map_is_active;
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index bf9ceab..4f8aecb 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -140,7 +140,8 @@ vgic_get_mmio_region(struct kvm_vcpu *vcpu, struct vgic_io_device *iodev,
>  struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
>  			      u32 intid);
>  void vgic_put_irq(struct kvm *kvm, struct vgic_irq *irq);
> -bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq);
> +bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq,
> +			   unsigned long flags);
>  void vgic_kick_vcpus(struct kvm *kvm);
>  
>  int vgic_check_ioaddr(struct kvm *kvm, phys_addr_t *ioaddr,
> 

Otherwise looks good to me.

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