Re: [PATCH v8 14/17] KVM: arm64: allow updates of LPI configuration table

Marc Zyngier
2016-07-11T16:59:12Z

On 05/07/16 12:23, Andre Przywara wrote:
> The (system-wide) LPI configuration table is held in a table in
> (guest) memory. To achieve reasonable performance, we cache this data
> in our struct vgic_irq. If the guest updates the configuration data
> (which consists of the enable bit and the priority value), it issues
> an INV or INVALL command to allow us to update our information.
> Provide functions that update that information for one LPI or all LPIs
> mapped to a specific collection.
>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
> virt/kvm/arm/vgic/vgic-its.c | 45 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 45 insertions(+)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 29bb4fe..5de71bd 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -94,6 +94,51 @@ struct its_itte {
>
> #define CBASER_ADDRESS(x) ((x) & GENMASK_ULL(51, 12))
> #define PENDBASER_ADDRESS(x) ((x) & GENMASK_ULL(51, 16))
> +#define PROPBASER_ADDRESS(x) ((x) & GENMASK_ULL(51, 12))

52 bits...

> +
> +#define GIC_LPI_OFFSET 8192
> +
> +#define LPI_PROP_ENABLE_BIT(p) ((p) & LPI_PROP_ENABLED)
> +#define LPI_PROP_PRIORITY(p) ((p) & 0xfc)
> +
> +/*
> + * Reads the configuration data for a given LPI from guest memory and
> + * updates the fields in struct vgic_irq.
> + * If filter_vcpu is not NULL, applies only if the IRQ is targeting this
> + * VCPU. Unconditionally applies if filter_vcpu is NULL.
> + */
> +static int update_lpi_config_filtered(struct kvm *kvm, struct vgic_irq *irq,
> + struct kvm_vcpu *filter_vcpu)
> +{
> + u64 propbase = PROPBASER_ADDRESS(kvm->arch.vgic.propbaser);
> + u8 prop;
> + int ret;
> +
> + ret = kvm_read_guest(kvm, propbase + irq->intid - GIC_LPI_OFFSET,
> + &prop, 1);
> +
> + if (ret)
> + return ret;
> +
> + spin_lock(&irq->irq_lock);
> +
> + 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);
> + } else {
> + spin_unlock(&irq->irq_lock);
> + }
> +
> + return 0;
> +}
> +
> +/* Updates the priority and enable bit for a given LPI. */
> +int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq)

static?

> +{
> + return update_lpi_config_filtered(kvm, irq, NULL);
> +}

I think you can drop the "_filtered" thing, and just have a
update_lpi_config() that takes a vcpu parameter. The comment at the top
is clear enough about the use case.

>
> static int vgic_its_copy_lpi_list(struct kvm *kvm, u32 **intid_ptr)
> {
>

Thanks,

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