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    Subject[PATCH 17/35] irqchip/gic-v4.1: Add VPE eviction callback
    Date
    When descheduling a VPE, special care must be taken to tell the GIC
    about whether we want to receive a doorbell or not. This is a
    major improvement on GICv4.0, where the doorbell had to be separately
    enabled/disabled.

    Signed-off-by: Marc Zyngier <maz@kernel.org>
    ---
    drivers/irqchip/irq-gic-v3-its.c | 53 +++++++++++++++++++++++++-------
    1 file changed, 42 insertions(+), 11 deletions(-)

    diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
    index 72d80daa7230..3079ce74def6 100644
    --- a/drivers/irqchip/irq-gic-v3-its.c
    +++ b/drivers/irqchip/irq-gic-v3-its.c
    @@ -2483,7 +2483,7 @@ static int __init allocate_lpi_tables(void)
    return 0;
    }

    -static u64 its_clear_vpend_valid(void __iomem *vlpi_base)
    +static u64 its_clear_vpend_valid(void __iomem *vlpi_base, u64 clr, u64 set)
    {
    u32 count = 1000000; /* 1s! */
    bool clean;
    @@ -2491,6 +2491,8 @@ static u64 its_clear_vpend_valid(void __iomem *vlpi_base)

    val = gits_read_vpendbaser(vlpi_base + GICR_VPENDBASER);
    val &= ~GICR_VPENDBASER_Valid;
    + val &= ~clr;
    + val |= set;
    gits_write_vpendbaser(val, vlpi_base + GICR_VPENDBASER);

    do {
    @@ -2503,6 +2505,11 @@ static u64 its_clear_vpend_valid(void __iomem *vlpi_base)
    }
    } while (!clean && count);

    + if (unlikely(val & GICR_VPENDBASER_Dirty)) {
    + pr_err_ratelimited("ITS virtual pending table not cleaning\n");
    + val |= GICR_VPENDBASER_PendingLast;
    + }
    +
    return val;
    }

    @@ -2611,7 +2618,7 @@ static void its_cpu_init_lpis(void)
    * ancient programming gets left in and has possibility of
    * corrupting memory.
    */
    - val = its_clear_vpend_valid(vlpi_base);
    + val = its_clear_vpend_valid(vlpi_base, 0, 0);
    WARN_ON(val & GICR_VPENDBASER_Dirty);
    }

    @@ -3289,16 +3296,10 @@ static void its_vpe_deschedule(struct its_vpe *vpe)
    void __iomem *vlpi_base = gic_data_rdist_vlpi_base();
    u64 val;

    - val = its_clear_vpend_valid(vlpi_base);
    + val = its_clear_vpend_valid(vlpi_base, 0, 0);

    - if (unlikely(val & GICR_VPENDBASER_Dirty)) {
    - pr_err_ratelimited("ITS virtual pending table not cleaning\n");
    - vpe->idai = false;
    - vpe->pending_last = true;
    - } else {
    - vpe->idai = !!(val & GICR_VPENDBASER_IDAI);
    - vpe->pending_last = !!(val & GICR_VPENDBASER_PendingLast);
    - }
    + vpe->idai = !!(val & GICR_VPENDBASER_IDAI);
    + vpe->pending_last = !!(val & GICR_VPENDBASER_PendingLast);
    }

    static void its_vpe_invall(struct its_vpe *vpe)
    @@ -3476,6 +3477,35 @@ static void its_vpe_4_1_schedule(struct its_vpe *vpe,
    gits_write_vpendbaser(val, vlpi_base + GICR_VPENDBASER);
    }

    +static void its_vpe_4_1_deschedule(struct its_vpe *vpe,
    + struct its_cmd_info *info)
    +{
    + void __iomem *vlpi_base = gic_data_rdist_vlpi_base();
    + u64 val;
    +
    + if (info->req_db) {
    + /*
    + * vPE is going to block: make the vPE non-resident with
    + * PendingLast clear and DB set. The GIC guarantees that if
    + * we read-back PendingLast clear, then a doorbell will be
    + * delivered when an interrupt comes.
    + */
    + val = its_clear_vpend_valid(vlpi_base,
    + GICR_VPENDBASER_PendingLast,
    + GICR_VPENDBASER_4_1_DB);
    + vpe->pending_last = !!(val & GICR_VPENDBASER_PendingLast);
    + } else {
    + /*
    + * We're not blocking, so just make the vPE non-resident
    + * with PendingLast set, indicating that we'll be back.
    + */
    + val = its_clear_vpend_valid(vlpi_base,
    + 0,
    + GICR_VPENDBASER_PendingLast);
    + vpe->pending_last = true;
    + }
    +}
    +
    static int its_vpe_4_1_set_vcpu_affinity(struct irq_data *d, void *vcpu_info)
    {
    struct its_vpe *vpe = irq_data_get_irq_chip_data(d);
    @@ -3487,6 +3517,7 @@ static int its_vpe_4_1_set_vcpu_affinity(struct irq_data *d, void *vcpu_info)
    return 0;

    case DESCHEDULE_VPE:
    + its_vpe_4_1_deschedule(vpe, info);
    return 0;

    case INVALL_VPE:
    --
    2.20.1
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