Re: [Xen-devel] [PATCH 42/57] ARM: new VGIC: Add TARGET registers handlers

[Andre Przywara <andre.przywara@xxxxxxxxxx>]

Hi,

On 08/03/18 16:18, Julien Grall wrote:
> Hi Andre,
> 
> On 05/03/18 16:04, Andre Przywara wrote:
>> The target register handlers are v2 emulation specific, so their
>> implementation lives entirely in vgic-mmio-v2.c.
>> We copy the old VGIC behaviour of assigning an IRQ to the first VCPU
>> set in the target mask instead of making it possibly pending on
>> multiple VCPUs.
>> We update the physical affinity of a hardware mapped vIRQ on the way.
>>
>> This is based on Linux commit 2c234d6f1826, written by Andre Przywara.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
>> ---
>> Changelog RFC ... v1:
>> - propagate affinity changes to hardware mapped IRQs
>>
>>   xen/arch/arm/vgic/vgic-mmio-v2.c | 64
>> +++++++++++++++++++++++++++++++++++++++-
>>   1 file changed, 63 insertions(+), 1 deletion(-)
>>
>> diff --git a/xen/arch/arm/vgic/vgic-mmio-v2.c
>> b/xen/arch/arm/vgic/vgic-mmio-v2.c
>> index d19ddd3f1e..01c6a7198c 100644
>> --- a/xen/arch/arm/vgic/vgic-mmio-v2.c
>> +++ b/xen/arch/arm/vgic/vgic-mmio-v2.c
>> @@ -72,6 +72,68 @@ static void vgic_mmio_write_v2_misc(struct vcpu *vcpu,
>>       }
>>   }
>>   +static unsigned long vgic_mmio_read_target(struct vcpu *vcpu,
>> +                                           paddr_t addr, unsigned int
>> len)
>> +{
>> +    uint32_t intid = VGIC_ADDR_TO_INTID(addr, 8);
>> +    uint32_t val = 0;
>> +    unsigned int i;
>> +
>> +    for ( i = 0; i < len; i++ )
>> +    {
>> +        struct vgic_irq *irq = vgic_get_irq(vcpu->domain, vcpu, intid
>> + i);
>> +
>> +        val |= (uint32_t)irq->targets << (i * 8);
>> +
>> +        vgic_put_irq(vcpu->domain, irq);
>> +    }
>> +
>> +    return val;
>> +}
>> +
>> +static void vgic_mmio_write_target(struct vcpu *vcpu,
>> +                                   paddr_t addr, unsigned int len,
>> +                                   unsigned long val)
>> +{
>> +    uint32_t intid = VGIC_ADDR_TO_INTID(addr, 8);
>> +    uint8_t cpu_mask = GENMASK(vcpu->domain->max_vcpus - 1, 0);
>> +    unsigned int i;
>> +    unsigned long flags;
>> +
>> +    /* GICD_ITARGETSR[0-7] are read-only */
>> +    if ( intid < VGIC_NR_PRIVATE_IRQS )
>> +        return;
>> +
>> +    for ( i = 0; i < len; i++ )
>> +    {
>> +        struct vgic_irq *irq = vgic_get_irq(vcpu->domain, NULL, intid
>> + i);
>> +        struct irq_desc *desc;
>> +
>> +        spin_lock_irqsave(&irq->irq_lock, flags);
>> +
>> +        irq->targets = (val >> (i * 8)) & cpu_mask;
>> +        if ( irq->targets )
>> +        {
>> +            irq->target_vcpu = vcpu->domain->vcpu[ffs(irq->targets) -
>> 1];
>> +            if ( irq->hw )
>> +                desc = irq_to_desc(irq->hwintid);
>> +            else
>> +                desc = NULL;
> 
> If you initialized desc to NULL during the declaration, then the else is
> not necessary.
> 
>> +        }
>> +        else {
>> +            irq->target_vcpu = NULL;
>> +            desc = NULL;
>> +        }
>> +
>> +        spin_unlock_irqrestore(&irq->irq_lock, flags);
>> +
>> +        if ( desc )
>> +            vgic_update_hardware_irq(desc, irq);
> 
> I can't find this function in the tree.

Ah, good catch, that's a rebase artefact. It gets fixed in the next patch.

Cheers,
Andre.

> 
>> +
>> +        vgic_put_irq(vcpu->domain, irq);
>> +    }
>> +}
>> +
>>   static const struct vgic_register_region vgic_v2_dist_registers[] = {
>>       REGISTER_DESC_WITH_LENGTH(GICD_CTLR,
>>           vgic_mmio_read_v2_misc, vgic_mmio_write_v2_misc, 12,
>> @@ -101,7 +163,7 @@ static const struct vgic_register_region
>> vgic_v2_dist_registers[] = {
>>           vgic_mmio_read_priority, vgic_mmio_write_priority, 8,
>>           VGIC_ACCESS_32bit | VGIC_ACCESS_8bit),
>>       REGISTER_DESC_WITH_BITS_PER_IRQ(GICD_ITARGETSR,
>> -        vgic_mmio_read_raz, vgic_mmio_write_wi, 8,
>> +        vgic_mmio_read_target, vgic_mmio_write_target, 8,
>>           VGIC_ACCESS_32bit | VGIC_ACCESS_8bit),
>>       REGISTER_DESC_WITH_BITS_PER_IRQ(GICD_ICFGR,
>>           vgic_mmio_read_config, vgic_mmio_write_config, 2,
>>
> 
> Cheers,
> 

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