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[v3,23/55] KVM: arm/arm64: vgic-new: Add CTLR, TYPER and IIDR handlers

Message ID 1462531568-9799-24-git-send-email-andre.przywara@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andre Przywara May 6, 2016, 10:45 a.m. UTC
From: Marc Zyngier <marc.zyngier@arm.com>

Those three registers are v2 emulation specific, so their implementation
lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
as their implementation is pretty simple.
When the guest enables the distributor, we kick all VCPUs to get
potentially pending interrupts serviced.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
Changelog RFC..v1:
- kick VCPUs is the distributor gets enabled
- improve comment

Changelog v1 .. v2:
- adapt to new MMIO framework
- use switch() statements to improve readability

Changelog v2 .. v3:
- add vgic_kick_vcpus() implementation

 include/linux/irqchip/arm-gic.h  |  1 +
 virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
 virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
 virt/kvm/arm/vgic/vgic.h         |  4 ++++
 4 files changed, 67 insertions(+), 1 deletion(-)

Comments

Christoffer Dall May 11, 2016, 12:05 p.m. UTC | #1
On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
> From: Marc Zyngier <marc.zyngier@arm.com>
> 
> Those three registers are v2 emulation specific, so their implementation
> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
> as their implementation is pretty simple.
> When the guest enables the distributor, we kick all VCPUs to get
> potentially pending interrupts serviced.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
> Changelog RFC..v1:
> - kick VCPUs is the distributor gets enabled
> - improve comment
> 
> Changelog v1 .. v2:
> - adapt to new MMIO framework
> - use switch() statements to improve readability
> 
> Changelog v2 .. v3:
> - add vgic_kick_vcpus() implementation
> 
>  include/linux/irqchip/arm-gic.h  |  1 +
>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
>  4 files changed, 67 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
> index be0d26f..fd05185 100644
> --- a/include/linux/irqchip/arm-gic.h
> +++ b/include/linux/irqchip/arm-gic.h
> @@ -33,6 +33,7 @@
>  
>  #define GIC_DIST_CTRL			0x000
>  #define GIC_DIST_CTR			0x004
> +#define GIC_DIST_IIDR			0x008
>  #define GIC_DIST_IGROUP			0x080
>  #define GIC_DIST_ENABLE_SET		0x100
>  #define GIC_DIST_ENABLE_CLEAR		0x180
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> index 2729a22..69e96f7 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> @@ -20,9 +20,55 @@
>  #include "vgic.h"
>  #include "vgic-mmio.h"
>  
> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
> +					    gpa_t addr, unsigned int len)
> +{
> +	u32 value;
> +
> +	switch (addr & 0x0c) {
> +	case GIC_DIST_CTRL:
> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
> +		break;
> +	case GIC_DIST_CTR:
> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
> +		value = (value >> 5) - 1;
> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
> +		break;
> +	case GIC_DIST_IIDR:
> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
> +		break;
> +	default:
> +		return 0;
> +	}
> +
> +	return extract_bytes(value, addr & 3, len);
> +}
> +
> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
> +				    gpa_t addr, unsigned int len,
> +				    unsigned long val)
> +{
> +	switch (addr & 0x0c) {
> +	case GIC_DIST_CTRL:
> +		if (!(addr & 1)) {

what is this !(addr & 1) check?

> +			struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> +			bool was_enabled = dist->enabled;
> +
> +			dist->enabled = val & GICD_ENABLE;
> +			if (!was_enabled && dist->enabled)
> +				vgic_kick_vcpus(vcpu->kvm);
> +		}
> +		break;
> +	case GIC_DIST_CTR:
> +	case GIC_DIST_IIDR:
> +		/* Nothing to do */
> +		return;
> +	}
> +}
> +
>  static const struct vgic_register_region vgic_v2_dist_registers[] = {
>  	REGISTER_DESC_WITH_LENGTH(GIC_DIST_CTRL,
> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 12),
> +		vgic_mmio_read_v2_misc, vgic_mmio_write_v2_misc, 12),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_IGROUP,
>  		vgic_mmio_read_rao, vgic_mmio_write_wi, 1),
>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_ENABLE_SET,
> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
> index c3dbcf3..5355de6 100644
> --- a/virt/kvm/arm/vgic/vgic.c
> +++ b/virt/kvm/arm/vgic/vgic.c
> @@ -544,3 +544,18 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
>  
>  	return pending;
>  }
> +
> +void vgic_kick_vcpus(struct kvm *kvm)
> +{
> +	struct kvm_vcpu *vcpu;
> +	int c;
> +
> +	/*
> +	 * We've injected an interrupt, time to find out who deserves
> +	 * a good kick...
> +	 */
> +	kvm_for_each_vcpu(c, vcpu, kvm) {
> +		if (kvm_vgic_vcpu_pending_irq(vcpu))
> +			kvm_vcpu_kick(vcpu);
> +	}
> +}
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index fd9acaa..cf62015 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -16,11 +16,15 @@
>  #ifndef __KVM_ARM_VGIC_NEW_H__
>  #define __KVM_ARM_VGIC_NEW_H__
>  
> +#define PRODUCT_ID_KVM		0x4b	/* ASCII code K */
> +#define IMPLEMENTER_ARM		0x43b
> +
>  #define vgic_irq_is_sgi(intid) ((intid) < VGIC_NR_SGIS)
>  
>  struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
>  			      u32 intid);
>  bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq);
> +void vgic_kick_vcpus(struct kvm *kvm);
>  
>  void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu);
>  void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu);
> -- 
> 2.7.3
> 
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
Andre Przywara May 11, 2016, 12:47 p.m. UTC | #2
Hej,

On 11/05/16 13:05, Christoffer Dall wrote:
> On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
>> From: Marc Zyngier <marc.zyngier@arm.com>
>>
>> Those three registers are v2 emulation specific, so their implementation
>> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
>> as their implementation is pretty simple.
>> When the guest enables the distributor, we kick all VCPUs to get
>> potentially pending interrupts serviced.
>>
>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>> Changelog RFC..v1:
>> - kick VCPUs is the distributor gets enabled
>> - improve comment
>>
>> Changelog v1 .. v2:
>> - adapt to new MMIO framework
>> - use switch() statements to improve readability
>>
>> Changelog v2 .. v3:
>> - add vgic_kick_vcpus() implementation
>>
>>  include/linux/irqchip/arm-gic.h  |  1 +
>>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
>>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
>>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
>>  4 files changed, 67 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
>> index be0d26f..fd05185 100644
>> --- a/include/linux/irqchip/arm-gic.h
>> +++ b/include/linux/irqchip/arm-gic.h
>> @@ -33,6 +33,7 @@
>>  
>>  #define GIC_DIST_CTRL			0x000
>>  #define GIC_DIST_CTR			0x004
>> +#define GIC_DIST_IIDR			0x008
>>  #define GIC_DIST_IGROUP			0x080
>>  #define GIC_DIST_ENABLE_SET		0x100
>>  #define GIC_DIST_ENABLE_CLEAR		0x180
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>> index 2729a22..69e96f7 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>> @@ -20,9 +20,55 @@
>>  #include "vgic.h"
>>  #include "vgic-mmio.h"
>>  
>> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
>> +					    gpa_t addr, unsigned int len)
>> +{
>> +	u32 value;
>> +
>> +	switch (addr & 0x0c) {
>> +	case GIC_DIST_CTRL:
>> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
>> +		break;
>> +	case GIC_DIST_CTR:
>> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
>> +		value = (value >> 5) - 1;
>> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
>> +		break;
>> +	case GIC_DIST_IIDR:
>> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
>> +		break;
>> +	default:
>> +		return 0;
>> +	}
>> +
>> +	return extract_bytes(value, addr & 3, len);
>> +}
>> +
>> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
>> +				    gpa_t addr, unsigned int len,
>> +				    unsigned long val)
>> +{
>> +	switch (addr & 0x0c) {
>> +	case GIC_DIST_CTRL:
>> +		if (!(addr & 1)) {
> 
> what is this !(addr & 1) check?

Mmmh, interesting. The original idea was that we care only about the
lowest significant byte. I guess this was somehow lost in translation
when Marc reworked the function. I think it should at least read:
"if (!(addr & 3))" to match the switch mask, otherwise for instance a
byte write to address 2 triggers the if branch as well.

I will fix the mask to 3 and add a comment.

Thanks,
Andre.


> 
>> +			struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>> +			bool was_enabled = dist->enabled;
>> +
>> +			dist->enabled = val & GICD_ENABLE;
>> +			if (!was_enabled && dist->enabled)
>> +				vgic_kick_vcpus(vcpu->kvm);
>> +		}
>> +		break;
>> +	case GIC_DIST_CTR:
>> +	case GIC_DIST_IIDR:
>> +		/* Nothing to do */
>> +		return;
>> +	}
>> +}
>> +
>>  static const struct vgic_register_region vgic_v2_dist_registers[] = {
>>  	REGISTER_DESC_WITH_LENGTH(GIC_DIST_CTRL,
>> -		vgic_mmio_read_raz, vgic_mmio_write_wi, 12),
>> +		vgic_mmio_read_v2_misc, vgic_mmio_write_v2_misc, 12),
>>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_IGROUP,
>>  		vgic_mmio_read_rao, vgic_mmio_write_wi, 1),
>>  	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_ENABLE_SET,
>> diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
>> index c3dbcf3..5355de6 100644
>> --- a/virt/kvm/arm/vgic/vgic.c
>> +++ b/virt/kvm/arm/vgic/vgic.c
>> @@ -544,3 +544,18 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
>>  
>>  	return pending;
>>  }
>> +
>> +void vgic_kick_vcpus(struct kvm *kvm)
>> +{
>> +	struct kvm_vcpu *vcpu;
>> +	int c;
>> +
>> +	/*
>> +	 * We've injected an interrupt, time to find out who deserves
>> +	 * a good kick...
>> +	 */
>> +	kvm_for_each_vcpu(c, vcpu, kvm) {
>> +		if (kvm_vgic_vcpu_pending_irq(vcpu))
>> +			kvm_vcpu_kick(vcpu);
>> +	}
>> +}
>> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
>> index fd9acaa..cf62015 100644
>> --- a/virt/kvm/arm/vgic/vgic.h
>> +++ b/virt/kvm/arm/vgic/vgic.h
>> @@ -16,11 +16,15 @@
>>  #ifndef __KVM_ARM_VGIC_NEW_H__
>>  #define __KVM_ARM_VGIC_NEW_H__
>>  
>> +#define PRODUCT_ID_KVM		0x4b	/* ASCII code K */
>> +#define IMPLEMENTER_ARM		0x43b
>> +
>>  #define vgic_irq_is_sgi(intid) ((intid) < VGIC_NR_SGIS)
>>  
>>  struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
>>  			      u32 intid);
>>  bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq);
>> +void vgic_kick_vcpus(struct kvm *kvm);
>>  
>>  void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu);
>>  void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu);
>> -- 
>> 2.7.3
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe kvm" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
Marc Zyngier May 11, 2016, 12:51 p.m. UTC | #3
On 11/05/16 13:05, Christoffer Dall wrote:
> On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
>> From: Marc Zyngier <marc.zyngier@arm.com>
>>
>> Those three registers are v2 emulation specific, so their implementation
>> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
>> as their implementation is pretty simple.
>> When the guest enables the distributor, we kick all VCPUs to get
>> potentially pending interrupts serviced.
>>
>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>> Changelog RFC..v1:
>> - kick VCPUs is the distributor gets enabled
>> - improve comment
>>
>> Changelog v1 .. v2:
>> - adapt to new MMIO framework
>> - use switch() statements to improve readability
>>
>> Changelog v2 .. v3:
>> - add vgic_kick_vcpus() implementation
>>
>>  include/linux/irqchip/arm-gic.h  |  1 +
>>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
>>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
>>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
>>  4 files changed, 67 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
>> index be0d26f..fd05185 100644
>> --- a/include/linux/irqchip/arm-gic.h
>> +++ b/include/linux/irqchip/arm-gic.h
>> @@ -33,6 +33,7 @@
>>  
>>  #define GIC_DIST_CTRL			0x000
>>  #define GIC_DIST_CTR			0x004
>> +#define GIC_DIST_IIDR			0x008
>>  #define GIC_DIST_IGROUP			0x080
>>  #define GIC_DIST_ENABLE_SET		0x100
>>  #define GIC_DIST_ENABLE_CLEAR		0x180
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>> index 2729a22..69e96f7 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>> @@ -20,9 +20,55 @@
>>  #include "vgic.h"
>>  #include "vgic-mmio.h"
>>  
>> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
>> +					    gpa_t addr, unsigned int len)
>> +{
>> +	u32 value;
>> +
>> +	switch (addr & 0x0c) {
>> +	case GIC_DIST_CTRL:
>> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
>> +		break;
>> +	case GIC_DIST_CTR:
>> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
>> +		value = (value >> 5) - 1;
>> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
>> +		break;
>> +	case GIC_DIST_IIDR:
>> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
>> +		break;
>> +	default:
>> +		return 0;
>> +	}
>> +
>> +	return extract_bytes(value, addr & 3, len);
>> +}
>> +
>> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
>> +				    gpa_t addr, unsigned int len,
>> +				    unsigned long val)
>> +{
>> +	switch (addr & 0x0c) {
>> +	case GIC_DIST_CTRL:
>> +		if (!(addr & 1)) {
> 
> what is this !(addr & 1) check?

We check that the write includes the lowest byte of the register. But as
we only have aligned accesses, it probably doesn't matter... I'll hack
that away.

Thanks,

	M.
Christoffer Dall May 11, 2016, 1:15 p.m. UTC | #4
On Wed, May 11, 2016 at 01:51:36PM +0100, Marc Zyngier wrote:
> On 11/05/16 13:05, Christoffer Dall wrote:
> > On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
> >> From: Marc Zyngier <marc.zyngier@arm.com>
> >>
> >> Those three registers are v2 emulation specific, so their implementation
> >> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
> >> as their implementation is pretty simple.
> >> When the guest enables the distributor, we kick all VCPUs to get
> >> potentially pending interrupts serviced.
> >>
> >> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> >> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> >> ---
> >> Changelog RFC..v1:
> >> - kick VCPUs is the distributor gets enabled
> >> - improve comment
> >>
> >> Changelog v1 .. v2:
> >> - adapt to new MMIO framework
> >> - use switch() statements to improve readability
> >>
> >> Changelog v2 .. v3:
> >> - add vgic_kick_vcpus() implementation
> >>
> >>  include/linux/irqchip/arm-gic.h  |  1 +
> >>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
> >>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
> >>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
> >>  4 files changed, 67 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
> >> index be0d26f..fd05185 100644
> >> --- a/include/linux/irqchip/arm-gic.h
> >> +++ b/include/linux/irqchip/arm-gic.h
> >> @@ -33,6 +33,7 @@
> >>  
> >>  #define GIC_DIST_CTRL			0x000
> >>  #define GIC_DIST_CTR			0x004
> >> +#define GIC_DIST_IIDR			0x008
> >>  #define GIC_DIST_IGROUP			0x080
> >>  #define GIC_DIST_ENABLE_SET		0x100
> >>  #define GIC_DIST_ENABLE_CLEAR		0x180
> >> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> index 2729a22..69e96f7 100644
> >> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >> @@ -20,9 +20,55 @@
> >>  #include "vgic.h"
> >>  #include "vgic-mmio.h"
> >>  
> >> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
> >> +					    gpa_t addr, unsigned int len)
> >> +{
> >> +	u32 value;
> >> +
> >> +	switch (addr & 0x0c) {
> >> +	case GIC_DIST_CTRL:
> >> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
> >> +		break;
> >> +	case GIC_DIST_CTR:
> >> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
> >> +		value = (value >> 5) - 1;
> >> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
> >> +		break;
> >> +	case GIC_DIST_IIDR:
> >> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
> >> +		break;
> >> +	default:
> >> +		return 0;
> >> +	}
> >> +
> >> +	return extract_bytes(value, addr & 3, len);
> >> +}
> >> +
> >> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
> >> +				    gpa_t addr, unsigned int len,
> >> +				    unsigned long val)
> >> +{
> >> +	switch (addr & 0x0c) {
> >> +	case GIC_DIST_CTRL:
> >> +		if (!(addr & 1)) {
> > 
> > what is this !(addr & 1) check?
> 
> We check that the write includes the lowest byte of the register. But as
> we only have aligned accesses, it probably doesn't matter... I'll hack
> that away.
> 
where do we check to only have aligned accesses?

-Christoffer
Marc Zyngier May 11, 2016, 1:27 p.m. UTC | #5
On 11/05/16 14:15, Christoffer Dall wrote:
> On Wed, May 11, 2016 at 01:51:36PM +0100, Marc Zyngier wrote:
>> On 11/05/16 13:05, Christoffer Dall wrote:
>>> On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
>>>> From: Marc Zyngier <marc.zyngier@arm.com>
>>>>
>>>> Those three registers are v2 emulation specific, so their implementation
>>>> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
>>>> as their implementation is pretty simple.
>>>> When the guest enables the distributor, we kick all VCPUs to get
>>>> potentially pending interrupts serviced.
>>>>
>>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>>>> ---
>>>> Changelog RFC..v1:
>>>> - kick VCPUs is the distributor gets enabled
>>>> - improve comment
>>>>
>>>> Changelog v1 .. v2:
>>>> - adapt to new MMIO framework
>>>> - use switch() statements to improve readability
>>>>
>>>> Changelog v2 .. v3:
>>>> - add vgic_kick_vcpus() implementation
>>>>
>>>>  include/linux/irqchip/arm-gic.h  |  1 +
>>>>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
>>>>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
>>>>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
>>>>  4 files changed, 67 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
>>>> index be0d26f..fd05185 100644
>>>> --- a/include/linux/irqchip/arm-gic.h
>>>> +++ b/include/linux/irqchip/arm-gic.h
>>>> @@ -33,6 +33,7 @@
>>>>  
>>>>  #define GIC_DIST_CTRL			0x000
>>>>  #define GIC_DIST_CTR			0x004
>>>> +#define GIC_DIST_IIDR			0x008
>>>>  #define GIC_DIST_IGROUP			0x080
>>>>  #define GIC_DIST_ENABLE_SET		0x100
>>>>  #define GIC_DIST_ENABLE_CLEAR		0x180
>>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> index 2729a22..69e96f7 100644
>>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>> @@ -20,9 +20,55 @@
>>>>  #include "vgic.h"
>>>>  #include "vgic-mmio.h"
>>>>  
>>>> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
>>>> +					    gpa_t addr, unsigned int len)
>>>> +{
>>>> +	u32 value;
>>>> +
>>>> +	switch (addr & 0x0c) {
>>>> +	case GIC_DIST_CTRL:
>>>> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
>>>> +		break;
>>>> +	case GIC_DIST_CTR:
>>>> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
>>>> +		value = (value >> 5) - 1;
>>>> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
>>>> +		break;
>>>> +	case GIC_DIST_IIDR:
>>>> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
>>>> +		break;
>>>> +	default:
>>>> +		return 0;
>>>> +	}
>>>> +
>>>> +	return extract_bytes(value, addr & 3, len);
>>>> +}
>>>> +
>>>> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
>>>> +				    gpa_t addr, unsigned int len,
>>>> +				    unsigned long val)
>>>> +{
>>>> +	switch (addr & 0x0c) {
>>>> +	case GIC_DIST_CTRL:
>>>> +		if (!(addr & 1)) {
>>>
>>> what is this !(addr & 1) check?
>>
>> We check that the write includes the lowest byte of the register. But as
>> we only have aligned accesses, it probably doesn't matter... I'll hack
>> that away.
>>
> where do we check to only have aligned accesses?

Looks like a missing feature. The v2 spec says:

4.1.4 GIC register access
All registers support 32-bit word accesses with the access type defined
in Table 4-1 on page 4-73 and Table 4-2 on page 4-74.
In addition, the GICD_IPRIORITYRn, GICD_ITARGETSRn, GICD_CPENDSGIRn, and
GICD_SPENDSGIRn registers support byte accesses.

Similar thing for v3 (8.1.3).

By the look of it, we should add checks in all accessors. I'll get onto it.

Thanks,

	M.
Andre Przywara May 11, 2016, 1:36 p.m. UTC | #6
Hi,

On 11/05/16 14:27, Marc Zyngier wrote:
> On 11/05/16 14:15, Christoffer Dall wrote:
>> On Wed, May 11, 2016 at 01:51:36PM +0100, Marc Zyngier wrote:
>>> On 11/05/16 13:05, Christoffer Dall wrote:
>>>> On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
>>>>> From: Marc Zyngier <marc.zyngier@arm.com>
>>>>>
>>>>> Those three registers are v2 emulation specific, so their implementation
>>>>> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
>>>>> as their implementation is pretty simple.
>>>>> When the guest enables the distributor, we kick all VCPUs to get
>>>>> potentially pending interrupts serviced.
>>>>>
>>>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>>>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>>>>> ---
>>>>> Changelog RFC..v1:
>>>>> - kick VCPUs is the distributor gets enabled
>>>>> - improve comment
>>>>>
>>>>> Changelog v1 .. v2:
>>>>> - adapt to new MMIO framework
>>>>> - use switch() statements to improve readability
>>>>>
>>>>> Changelog v2 .. v3:
>>>>> - add vgic_kick_vcpus() implementation
>>>>>
>>>>>  include/linux/irqchip/arm-gic.h  |  1 +
>>>>>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
>>>>>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
>>>>>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
>>>>>  4 files changed, 67 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
>>>>> index be0d26f..fd05185 100644
>>>>> --- a/include/linux/irqchip/arm-gic.h
>>>>> +++ b/include/linux/irqchip/arm-gic.h
>>>>> @@ -33,6 +33,7 @@
>>>>>  
>>>>>  #define GIC_DIST_CTRL			0x000
>>>>>  #define GIC_DIST_CTR			0x004
>>>>> +#define GIC_DIST_IIDR			0x008
>>>>>  #define GIC_DIST_IGROUP			0x080
>>>>>  #define GIC_DIST_ENABLE_SET		0x100
>>>>>  #define GIC_DIST_ENABLE_CLEAR		0x180
>>>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>>> index 2729a22..69e96f7 100644
>>>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>>> @@ -20,9 +20,55 @@
>>>>>  #include "vgic.h"
>>>>>  #include "vgic-mmio.h"
>>>>>  
>>>>> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
>>>>> +					    gpa_t addr, unsigned int len)
>>>>> +{
>>>>> +	u32 value;
>>>>> +
>>>>> +	switch (addr & 0x0c) {
>>>>> +	case GIC_DIST_CTRL:
>>>>> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
>>>>> +		break;
>>>>> +	case GIC_DIST_CTR:
>>>>> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
>>>>> +		value = (value >> 5) - 1;
>>>>> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
>>>>> +		break;
>>>>> +	case GIC_DIST_IIDR:
>>>>> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
>>>>> +		break;
>>>>> +	default:
>>>>> +		return 0;
>>>>> +	}
>>>>> +
>>>>> +	return extract_bytes(value, addr & 3, len);
>>>>> +}
>>>>> +
>>>>> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
>>>>> +				    gpa_t addr, unsigned int len,
>>>>> +				    unsigned long val)
>>>>> +{
>>>>> +	switch (addr & 0x0c) {
>>>>> +	case GIC_DIST_CTRL:
>>>>> +		if (!(addr & 1)) {
>>>>
>>>> what is this !(addr & 1) check?
>>>
>>> We check that the write includes the lowest byte of the register. But as
>>> we only have aligned accesses, it probably doesn't matter... I'll hack
>>> that away.
>>>
>> where do we check to only have aligned accesses?
> 
> Looks like a missing feature. The v2 spec says:
> 
> 4.1.4 GIC register access
> All registers support 32-bit word accesses with the access type defined
> in Table 4-1 on page 4-73 and Table 4-2 on page 4-74.
> In addition, the GICD_IPRIORITYRn, GICD_ITARGETSRn, GICD_CPENDSGIRn, and
> GICD_SPENDSGIRn registers support byte accesses.
> 
> Similar thing for v3 (8.1.3).
> 
> By the look of it, we should add checks in all accessors. I'll get onto it.

What about to tag every register in our vgic_register_region with a
possible access width and do a generic check in
dispatch_mmio_{read,write}? Then we wouldn't need to touch every handler.

Cheers,
Andre.
Christoffer Dall May 11, 2016, 1:38 p.m. UTC | #7
On Wed, May 11, 2016 at 02:27:53PM +0100, Marc Zyngier wrote:
> On 11/05/16 14:15, Christoffer Dall wrote:
> > On Wed, May 11, 2016 at 01:51:36PM +0100, Marc Zyngier wrote:
> >> On 11/05/16 13:05, Christoffer Dall wrote:
> >>> On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
> >>>> From: Marc Zyngier <marc.zyngier@arm.com>
> >>>>
> >>>> Those three registers are v2 emulation specific, so their implementation
> >>>> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
> >>>> as their implementation is pretty simple.
> >>>> When the guest enables the distributor, we kick all VCPUs to get
> >>>> potentially pending interrupts serviced.
> >>>>
> >>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> >>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> >>>> ---
> >>>> Changelog RFC..v1:
> >>>> - kick VCPUs is the distributor gets enabled
> >>>> - improve comment
> >>>>
> >>>> Changelog v1 .. v2:
> >>>> - adapt to new MMIO framework
> >>>> - use switch() statements to improve readability
> >>>>
> >>>> Changelog v2 .. v3:
> >>>> - add vgic_kick_vcpus() implementation
> >>>>
> >>>>  include/linux/irqchip/arm-gic.h  |  1 +
> >>>>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
> >>>>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
> >>>>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
> >>>>  4 files changed, 67 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
> >>>> index be0d26f..fd05185 100644
> >>>> --- a/include/linux/irqchip/arm-gic.h
> >>>> +++ b/include/linux/irqchip/arm-gic.h
> >>>> @@ -33,6 +33,7 @@
> >>>>  
> >>>>  #define GIC_DIST_CTRL			0x000
> >>>>  #define GIC_DIST_CTR			0x004
> >>>> +#define GIC_DIST_IIDR			0x008
> >>>>  #define GIC_DIST_IGROUP			0x080
> >>>>  #define GIC_DIST_ENABLE_SET		0x100
> >>>>  #define GIC_DIST_ENABLE_CLEAR		0x180
> >>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >>>> index 2729a22..69e96f7 100644
> >>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> >>>> @@ -20,9 +20,55 @@
> >>>>  #include "vgic.h"
> >>>>  #include "vgic-mmio.h"
> >>>>  
> >>>> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
> >>>> +					    gpa_t addr, unsigned int len)
> >>>> +{
> >>>> +	u32 value;
> >>>> +
> >>>> +	switch (addr & 0x0c) {
> >>>> +	case GIC_DIST_CTRL:
> >>>> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
> >>>> +		break;
> >>>> +	case GIC_DIST_CTR:
> >>>> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
> >>>> +		value = (value >> 5) - 1;
> >>>> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
> >>>> +		break;
> >>>> +	case GIC_DIST_IIDR:
> >>>> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
> >>>> +		break;
> >>>> +	default:
> >>>> +		return 0;
> >>>> +	}
> >>>> +
> >>>> +	return extract_bytes(value, addr & 3, len);
> >>>> +}
> >>>> +
> >>>> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
> >>>> +				    gpa_t addr, unsigned int len,
> >>>> +				    unsigned long val)
> >>>> +{
> >>>> +	switch (addr & 0x0c) {
> >>>> +	case GIC_DIST_CTRL:
> >>>> +		if (!(addr & 1)) {
> >>>
> >>> what is this !(addr & 1) check?
> >>
> >> We check that the write includes the lowest byte of the register. But as
> >> we only have aligned accesses, it probably doesn't matter... I'll hack
> >> that away.
> >>
> > where do we check to only have aligned accesses?
> 
> Looks like a missing feature. The v2 spec says:
> 
> 4.1.4 GIC register access
> All registers support 32-bit word accesses with the access type defined
> in Table 4-1 on page 4-73 and Table 4-2 on page 4-74.
> In addition, the GICD_IPRIORITYRn, GICD_ITARGETSRn, GICD_CPENDSGIRn, and
> GICD_SPENDSGIRn registers support byte accesses.
> 
> Similar thing for v3 (8.1.3).
> 
> By the look of it, we should add checks in all accessors. I'll get onto it.
> 
Yeah, that's probably the easiest.

-Christoffer
Marc Zyngier May 11, 2016, 2:40 p.m. UTC | #8
On 11/05/16 14:36, Andre Przywara wrote:
> Hi,
> 
> On 11/05/16 14:27, Marc Zyngier wrote:
>> On 11/05/16 14:15, Christoffer Dall wrote:
>>> On Wed, May 11, 2016 at 01:51:36PM +0100, Marc Zyngier wrote:
>>>> On 11/05/16 13:05, Christoffer Dall wrote:
>>>>> On Fri, May 06, 2016 at 11:45:36AM +0100, Andre Przywara wrote:
>>>>>> From: Marc Zyngier <marc.zyngier@arm.com>
>>>>>>
>>>>>> Those three registers are v2 emulation specific, so their implementation
>>>>>> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
>>>>>> as their implementation is pretty simple.
>>>>>> When the guest enables the distributor, we kick all VCPUs to get
>>>>>> potentially pending interrupts serviced.
>>>>>>
>>>>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>>>>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>>>>>> ---
>>>>>> Changelog RFC..v1:
>>>>>> - kick VCPUs is the distributor gets enabled
>>>>>> - improve comment
>>>>>>
>>>>>> Changelog v1 .. v2:
>>>>>> - adapt to new MMIO framework
>>>>>> - use switch() statements to improve readability
>>>>>>
>>>>>> Changelog v2 .. v3:
>>>>>> - add vgic_kick_vcpus() implementation
>>>>>>
>>>>>>  include/linux/irqchip/arm-gic.h  |  1 +
>>>>>>  virt/kvm/arm/vgic/vgic-mmio-v2.c | 48 +++++++++++++++++++++++++++++++++++++++-
>>>>>>  virt/kvm/arm/vgic/vgic.c         | 15 +++++++++++++
>>>>>>  virt/kvm/arm/vgic/vgic.h         |  4 ++++
>>>>>>  4 files changed, 67 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
>>>>>> index be0d26f..fd05185 100644
>>>>>> --- a/include/linux/irqchip/arm-gic.h
>>>>>> +++ b/include/linux/irqchip/arm-gic.h
>>>>>> @@ -33,6 +33,7 @@
>>>>>>  
>>>>>>  #define GIC_DIST_CTRL			0x000
>>>>>>  #define GIC_DIST_CTR			0x004
>>>>>> +#define GIC_DIST_IIDR			0x008
>>>>>>  #define GIC_DIST_IGROUP			0x080
>>>>>>  #define GIC_DIST_ENABLE_SET		0x100
>>>>>>  #define GIC_DIST_ENABLE_CLEAR		0x180
>>>>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>>>> index 2729a22..69e96f7 100644
>>>>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
>>>>>> @@ -20,9 +20,55 @@
>>>>>>  #include "vgic.h"
>>>>>>  #include "vgic-mmio.h"
>>>>>>  
>>>>>> +static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
>>>>>> +					    gpa_t addr, unsigned int len)
>>>>>> +{
>>>>>> +	u32 value;
>>>>>> +
>>>>>> +	switch (addr & 0x0c) {
>>>>>> +	case GIC_DIST_CTRL:
>>>>>> +		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
>>>>>> +		break;
>>>>>> +	case GIC_DIST_CTR:
>>>>>> +		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
>>>>>> +		value = (value >> 5) - 1;
>>>>>> +		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
>>>>>> +		break;
>>>>>> +	case GIC_DIST_IIDR:
>>>>>> +		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
>>>>>> +		break;
>>>>>> +	default:
>>>>>> +		return 0;
>>>>>> +	}
>>>>>> +
>>>>>> +	return extract_bytes(value, addr & 3, len);
>>>>>> +}
>>>>>> +
>>>>>> +static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
>>>>>> +				    gpa_t addr, unsigned int len,
>>>>>> +				    unsigned long val)
>>>>>> +{
>>>>>> +	switch (addr & 0x0c) {
>>>>>> +	case GIC_DIST_CTRL:
>>>>>> +		if (!(addr & 1)) {
>>>>>
>>>>> what is this !(addr & 1) check?
>>>>
>>>> We check that the write includes the lowest byte of the register. But as
>>>> we only have aligned accesses, it probably doesn't matter... I'll hack
>>>> that away.
>>>>
>>> where do we check to only have aligned accesses?
>>
>> Looks like a missing feature. The v2 spec says:
>>
>> 4.1.4 GIC register access
>> All registers support 32-bit word accesses with the access type defined
>> in Table 4-1 on page 4-73 and Table 4-2 on page 4-74.
>> In addition, the GICD_IPRIORITYRn, GICD_ITARGETSRn, GICD_CPENDSGIRn, and
>> GICD_SPENDSGIRn registers support byte accesses.
>>
>> Similar thing for v3 (8.1.3).
>>
>> By the look of it, we should add checks in all accessors. I'll get onto it.
> 
> What about to tag every register in our vgic_register_region with a
> possible access width and do a generic check in
> dispatch_mmio_{read,write}? Then we wouldn't need to touch every handler.

That's my plan.

	M.
diff mbox

Patch

diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
index be0d26f..fd05185 100644
--- a/include/linux/irqchip/arm-gic.h
+++ b/include/linux/irqchip/arm-gic.h
@@ -33,6 +33,7 @@ 
 
 #define GIC_DIST_CTRL			0x000
 #define GIC_DIST_CTR			0x004
+#define GIC_DIST_IIDR			0x008
 #define GIC_DIST_IGROUP			0x080
 #define GIC_DIST_ENABLE_SET		0x100
 #define GIC_DIST_ENABLE_CLEAR		0x180
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
index 2729a22..69e96f7 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
@@ -20,9 +20,55 @@ 
 #include "vgic.h"
 #include "vgic-mmio.h"
 
+static unsigned long vgic_mmio_read_v2_misc(struct kvm_vcpu *vcpu,
+					    gpa_t addr, unsigned int len)
+{
+	u32 value;
+
+	switch (addr & 0x0c) {
+	case GIC_DIST_CTRL:
+		value = vcpu->kvm->arch.vgic.enabled ? GICD_ENABLE : 0;
+		break;
+	case GIC_DIST_CTR:
+		value = vcpu->kvm->arch.vgic.nr_spis + VGIC_NR_PRIVATE_IRQS;
+		value = (value >> 5) - 1;
+		value |= (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
+		break;
+	case GIC_DIST_IIDR:
+		value = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
+		break;
+	default:
+		return 0;
+	}
+
+	return extract_bytes(value, addr & 3, len);
+}
+
+static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
+				    gpa_t addr, unsigned int len,
+				    unsigned long val)
+{
+	switch (addr & 0x0c) {
+	case GIC_DIST_CTRL:
+		if (!(addr & 1)) {
+			struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+			bool was_enabled = dist->enabled;
+
+			dist->enabled = val & GICD_ENABLE;
+			if (!was_enabled && dist->enabled)
+				vgic_kick_vcpus(vcpu->kvm);
+		}
+		break;
+	case GIC_DIST_CTR:
+	case GIC_DIST_IIDR:
+		/* Nothing to do */
+		return;
+	}
+}
+
 static const struct vgic_register_region vgic_v2_dist_registers[] = {
 	REGISTER_DESC_WITH_LENGTH(GIC_DIST_CTRL,
-		vgic_mmio_read_raz, vgic_mmio_write_wi, 12),
+		vgic_mmio_read_v2_misc, vgic_mmio_write_v2_misc, 12),
 	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_IGROUP,
 		vgic_mmio_read_rao, vgic_mmio_write_wi, 1),
 	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_ENABLE_SET,
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index c3dbcf3..5355de6 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -544,3 +544,18 @@  int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
 
 	return pending;
 }
+
+void vgic_kick_vcpus(struct kvm *kvm)
+{
+	struct kvm_vcpu *vcpu;
+	int c;
+
+	/*
+	 * We've injected an interrupt, time to find out who deserves
+	 * a good kick...
+	 */
+	kvm_for_each_vcpu(c, vcpu, kvm) {
+		if (kvm_vgic_vcpu_pending_irq(vcpu))
+			kvm_vcpu_kick(vcpu);
+	}
+}
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index fd9acaa..cf62015 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -16,11 +16,15 @@ 
 #ifndef __KVM_ARM_VGIC_NEW_H__
 #define __KVM_ARM_VGIC_NEW_H__
 
+#define PRODUCT_ID_KVM		0x4b	/* ASCII code K */
+#define IMPLEMENTER_ARM		0x43b
+
 #define vgic_irq_is_sgi(intid) ((intid) < VGIC_NR_SGIS)
 
 struct vgic_irq *vgic_get_irq(struct kvm *kvm, struct kvm_vcpu *vcpu,
 			      u32 intid);
 bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq);
+void vgic_kick_vcpus(struct kvm *kvm);
 
 void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu);
 void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu);