On 07/09/2015 03:19 PM, Marc Zyngier wrote:
> Commit 0a4377de3056 ("genirq: Introduce irq_set_vcpu_affinity() to
> target an interrupt to a VCPU") added just what we needed at the
> lowest level to allow an interrupt to be deactivated by a guest.
>
> When such a request reaches the GIC, it knows it doesn't need to
> perform the deactivation anymore, and can safely leave the guest
> do its magic. This of course requires additional support in both
> VFIO and KVM.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> drivers/irqchip/irq-gic-v3.c | 29 +++++++++++++++++++++++++++--
> 1 file changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index e02592b..a1ca9e6 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -70,6 +70,11 @@ static inline int gic_irq_in_rdist(struct irq_data *d)
> return gic_irq(d) < 32;
> }
>
> +static inline bool forwarded_irq(struct irq_data *d)
> +{
> + return d->handler_data != NULL;
> +}
> +
> static inline void __iomem *gic_dist_base(struct irq_data *d)
> {
> if (gic_irq_in_rdist(d)) /* SGI+PPI -> SGI_base for this CPU */
> @@ -231,6 +236,12 @@ static void gic_poke_irq(struct irq_data *d, u32 offset)
> static void gic_mask_irq(struct irq_data *d)
> {
> gic_poke_irq(d, GICD_ICENABLER);
> + /*
> + * When masking a forwarded interrupt, make sure it is
> + * deactivated as well.
To me it is not straightforward to understand why a forwarded IRQ would
need to be DIR'ed when masked. This is needed because of the disable_irq
optimisation, I would add a related comment.
Eric
> + */
> + if (static_key_true(&supports_deactivate) && forwarded_irq(d))
> + gic_poke_irq(d, GICD_ICACTIVER);
> }
>
> static void gic_unmask_irq(struct irq_data *d)
> @@ -296,8 +307,11 @@ static int gic_irq_get_irqchip_state(struct irq_data *d,
> static void gic_eoi_irq(struct irq_data *d)
> {
> if (static_key_true(&supports_deactivate)) {
> - /* No need to deactivate an LPI */
> - if (gic_irq(d) >= 8192)
> + /*
> + * No need to deactivate an LPI, or an interrupt that
> + * is is getting forwarded to a vcpu.
> + */
> + if (gic_irq(d) >= 8192 || forwarded_irq(d))
> return;
> gic_write_dir(gic_irq(d));
> } else {
> @@ -331,6 +345,16 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
> return gic_configure_irq(irq, type, base, rwp_wait);
> }
>
> +static int gic_irq_set_vcpu_affinity(struct irq_data *d, void *vcpu)
> +{
> + if (static_key_true(&supports_deactivate)) {
> + d->handler_data = vcpu;
> + return 0;
> + }
> +
> + return -EINVAL;
> +}
> +
> static u64 gic_mpidr_to_affinity(u64 mpidr)
> {
> u64 aff;
> @@ -678,6 +702,7 @@ static struct irq_chip gic_chip = {
> .irq_set_affinity = gic_set_affinity,
> .irq_get_irqchip_state = gic_irq_get_irqchip_state,
> .irq_set_irqchip_state = gic_irq_set_irqchip_state,
> + .irq_set_vcpu_affinity = gic_irq_set_vcpu_affinity,
> .flags = IRQCHIP_SET_TYPE_MASKED,
> };
>
>
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