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Subject[PATCH v3 12/32] 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.

Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
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 49850297fe56..a5567d099a3e 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -2631,7 +2631,7 @@ 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;
@@ -2639,6 +2639,8 @@ 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 {
@@ -2651,6 +2653,11 @@ 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;
}

@@ -2759,7 +2766,7 @@ 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);
}

@@ -3439,16 +3446,10 @@ 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)
@@ -3640,6 +3641,35 @@ 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);
@@ -3651,6 +3681,7 @@ 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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