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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 21/39] ARM: new VGIC: Add ACTIVE registers handlers
On Wed, 21 Mar 2018, Andre Przywara wrote:
> The active register handlers are shared between the v2 and v3 emulation,
> so their implementation goes into vgic-mmio.c, to be easily referenced
> from the v3 emulation as well later.
> Since activation/deactivation of an interrupt may happen entirely in the
> guest without it ever exiting, we need some extra logic to properly track
> the active state.
> For clearing the active state, we would basically have to halt the guest
> to make sure this is properly propagated into the respective VCPUs.
> This is not yet implemented in Xen.
> Fortunately this feature is mostly used to reset a just in initialised
> GIC, so chances are we are tasked to clear bits that are already zero.
> Add a simple check to avoid pointless warnings in this case.
>
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
> Reviewed-by: Julien Grall <julien.grall@xxxxxxx>
> ---
> xen/arch/arm/vgic/vgic-mmio-v2.c | 4 +-
> xen/arch/arm/vgic/vgic-mmio.c | 91
> ++++++++++++++++++++++++++++++++++++++++
> xen/arch/arm/vgic/vgic-mmio.h | 11 +++++
> 3 files changed, 104 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/arm/vgic/vgic-mmio-v2.c
> b/xen/arch/arm/vgic/vgic-mmio-v2.c
> index a48c554040..724681e0f8 100644
> --- a/xen/arch/arm/vgic/vgic-mmio-v2.c
> +++ b/xen/arch/arm/vgic/vgic-mmio-v2.c
> @@ -101,10 +101,10 @@ static const struct vgic_register_region
> vgic_v2_dist_registers[] = {
> vgic_mmio_read_pending, vgic_mmio_write_cpending, 1,
> VGIC_ACCESS_32bit),
> REGISTER_DESC_WITH_BITS_PER_IRQ(GICD_ISACTIVER,
> - vgic_mmio_read_raz, vgic_mmio_write_wi, 1,
> + vgic_mmio_read_active, vgic_mmio_write_sactive, 1,
> VGIC_ACCESS_32bit),
> REGISTER_DESC_WITH_BITS_PER_IRQ(GICD_ICACTIVER,
> - vgic_mmio_read_raz, vgic_mmio_write_wi, 1,
> + vgic_mmio_read_active, vgic_mmio_write_cactive, 1,
> VGIC_ACCESS_32bit),
> REGISTER_DESC_WITH_BITS_PER_IRQ(GICD_IPRIORITYR,
> vgic_mmio_read_raz, vgic_mmio_write_wi, 8,
> diff --git a/xen/arch/arm/vgic/vgic-mmio.c b/xen/arch/arm/vgic/vgic-mmio.c
> index 53b8978c02..b79e431f50 100644
> --- a/xen/arch/arm/vgic/vgic-mmio.c
> +++ b/xen/arch/arm/vgic/vgic-mmio.c
> @@ -281,6 +281,97 @@ void vgic_mmio_write_cpending(struct vcpu *vcpu,
> }
> }
>
> +/*
> + * The actual active bit for a virtual IRQ is held in the LR. Our shadow
> + * copy in struct vgic_irq is only synced when needed and may not be
> + * up-to-date all of the time.
> + * Returning the actual active state is quite costly (stopping all
> + * VCPUs processing any affected vIRQs), so we use a simple implementation
> + * to get the best possible answer.
> + */
> +unsigned long vgic_mmio_read_active(struct vcpu *vcpu,
> + paddr_t addr, unsigned int len)
> +{
> + uint32_t intid = VGIC_ADDR_TO_INTID(addr, 1);
> + uint32_t value = 0;
> + unsigned int i;
> +
> + /* Loop over all IRQs affected by this read */
> + for ( i = 0; i < len * 8; i++ )
> + {
> + struct vgic_irq *irq = vgic_get_irq(vcpu->domain, vcpu, intid + i);
> +
> + if ( irq->active )
> + value |= (1U << i);
Need for lock? I guess one answer will be good for all these patches :-)
Aside from this, everything else looks good.
> + vgic_put_irq(vcpu->domain, irq);
> + }
> +
> + return value;
> +}
> +
> +/*
> + * We don't actually support clearing the active state of an IRQ (yet).
> + * However there is a chance that most guests use this for initialization.
> + * We check whether this MMIO access would actually affect any active IRQ,
> + * and only print our warning in this case. So clearing already non-active
> + * IRQs would not be moaned about in the logs.
> + */
> +void vgic_mmio_write_cactive(struct vcpu *vcpu,
> + paddr_t addr, unsigned int len,
> + unsigned long val)
> +{
> + uint32_t intid = VGIC_ADDR_TO_INTID(addr, 1);
> + unsigned int i;
> +
> + for_each_set_bit( i, &val, len * 8 )
> + {
> + struct vgic_irq *irq = vgic_get_irq(vcpu->domain, vcpu, intid + i);
> +
> + /*
> + * If we know that the IRQ is active or we can't be sure about
> + * it (because it is currently in a CPU), log the not properly
> + * emulated MMIO access.
> + */
> + if ( irq->active || irq->vcpu )
> + printk(XENLOG_G_ERR
> + "%pv: vGICD: IRQ%u: clearing active state not
> supported\n",
> + vcpu, irq->intid);
> +
> + vgic_put_irq(vcpu->domain, irq);
> + }
> +}
> +
> +/*
> + * We don't actually support setting the active state of an IRQ (yet).
> + * We check whether this MMIO access would actually affect any non-active
> IRQ,
> + * and only print our warning in this case.
> + */
> +void vgic_mmio_write_sactive(struct vcpu *vcpu,
> + paddr_t addr, unsigned int len,
> + unsigned long val)
> +{
> + uint32_t intid = VGIC_ADDR_TO_INTID(addr, 1);
> + unsigned int i;
> +
> + for_each_set_bit( i, &val, len * 8 )
> + {
> + struct vgic_irq *irq = vgic_get_irq(vcpu->domain, vcpu, intid + i);
> +
> + /*
> + * If we know that the IRQ is not active or we can't be sure about
> + * it (because it is currently in a CPU), log the not properly
> + * emulated MMIO access.
> + */
> + if ( !irq->active || irq->vcpu )
> + printk(XENLOG_G_ERR
> + "%pv: vGICD: IRQ%u: setting active state not supported\n",
> + vcpu, irq->intid);
> +
> + vgic_put_irq(vcpu->domain, irq);
> + }
> +}
> +
> static int match_region(const void *key, const void *elt)
> {
> const unsigned int offset = (unsigned long)key;
> diff --git a/xen/arch/arm/vgic/vgic-mmio.h b/xen/arch/arm/vgic/vgic-mmio.h
> index 5c927f28b0..832e2eb3d8 100644
> --- a/xen/arch/arm/vgic/vgic-mmio.h
> +++ b/xen/arch/arm/vgic/vgic-mmio.h
> @@ -108,6 +108,17 @@ void vgic_mmio_write_cpending(struct vcpu *vcpu,
> paddr_t addr, unsigned int len,
> unsigned long val);
>
> +unsigned long vgic_mmio_read_active(struct vcpu *vcpu,
> + paddr_t addr, unsigned int len);
> +
> +void vgic_mmio_write_cactive(struct vcpu *vcpu,
> + paddr_t addr, unsigned int len,
> + unsigned long val);
> +
> +void vgic_mmio_write_sactive(struct vcpu *vcpu,
> + paddr_t addr, unsigned int len,
> + unsigned long val);
> +
> unsigned int vgic_v2_init_dist_iodev(struct vgic_io_device *dev);
>
> #endif
> --
> 2.14.1
>
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