With posted MSIs, end of interrupt is handled by the notification
handler. Each MSI handler does not go through local APIC IRR, ISR
processing. There's no need to do apic_eoi() in those handlers.
Add a new acpi_ack_irq_no_eoi() for the posted MSI IR chip. At runtime
the call trace looks like:
__sysvec_posted_msi_notification() {
irq_chip_ack_parent() {
apic_ack_irq_no_eoi();
}
handle_irq_event() {
handle_irq_event_percpu() {
driver_handler()
}
}
IO-APIC IR is excluded the from posted MSI, we need to make sure it
still performs EOI.
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/apic.h | 1 +
arch/x86/kernel/apic/io_apic.c | 2 +-
arch/x86/kernel/apic/vector.c | 5 ++++
drivers/iommu/intel/irq_remapping.c | 38 ++++++++++++++++++++++++++++-
4 files changed, 44 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 5af4ec1a0f71..a88015d5638b 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -485,6 +485,7 @@ static inline void apic_setup_apic_calls(void) { }
#endif /* CONFIG_X86_LOCAL_APIC */
extern void apic_ack_irq(struct irq_data *data);
+extern void apic_ack_irq_no_eoi(struct irq_data *data);
static inline bool lapic_vector_set_in_irr(unsigned int vector)
{
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 00da6cf6b07d..ca398ee9075b 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1993,7 +1993,7 @@ static struct irq_chip ioapic_ir_chip __read_mostly = {
.irq_startup = startup_ioapic_irq,
.irq_mask = mask_ioapic_irq,
.irq_unmask = unmask_ioapic_irq,
- .irq_ack = irq_chip_ack_parent,
+ .irq_ack = apic_ack_irq,
.irq_eoi = ioapic_ir_ack_level,
.irq_set_affinity = ioapic_set_affinity,
.irq_retrigger = irq_chip_retrigger_hierarchy,
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 14fc33cfdb37..01223ac4f57a 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -911,6 +911,11 @@ void apic_ack_irq(struct irq_data *irqd)
apic_eoi();
}
+void apic_ack_irq_no_eoi(struct irq_data *irqd)
+{
+ irq_move_irq(irqd);
+}
+
void apic_ack_edge(struct irq_data *irqd)
{
irq_complete_move(irqd_cfg(irqd));
diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
index 29b9e55dcf26..f2870d3c8313 100644
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -1233,6 +1233,42 @@ static struct irq_chip intel_ir_chip = {
.irq_set_vcpu_affinity = intel_ir_set_vcpu_affinity,
};
+/*
+ * With posted MSIs, all vectors are multiplexed into a single notification
+ * vector. Devices MSIs are then dispatched in a demux loop where
+ * EOIs can be coalesced as well.
+ *
+ * IR chip "INTEL-IR-POST" does not do EOI on ACK instead letting posted
+ * interrupt notification handler to perform EOI.
+ *
+ * For the example below, 3 MSIs are coalesced in one CPU notification. Only
+ * one apic_eoi() is needed.
+ *
+ * __sysvec_posted_msi_notification() {
+ * irq_enter()
+ * handle_edge_irq()
+ * irq_chip_ack_parent()
+ * apic_ack_irq_no_eoi()
+ * handle_irq()
+ * handle_edge_irq()
+ * irq_chip_ack_parent()
+ * apic_ack_irq_no_eoi()
+ * handle_irq()
+ * handle_edge_irq()
+ * irq_chip_ack_parent()
+ * apic_ack_irq_no_eoi()
+ * handle_irq()
+ * apic_eoi()
+ * irq_exit()
+ */
+static struct irq_chip intel_ir_chip_post_msi = {
+ .name = "INTEL-IR-POST",
+ .irq_ack = apic_ack_irq_no_eoi,
+ .irq_set_affinity = intel_ir_set_affinity,
+ .irq_compose_msi_msg = intel_ir_compose_msi_msg,
+ .irq_set_vcpu_affinity = intel_ir_set_vcpu_affinity,
+};
+
static void fill_msi_msg(struct msi_msg *msg, u32 index, u32 subhandle)
{
memset(msg, 0, sizeof(*msg));
@@ -1361,7 +1397,7 @@ static int intel_irq_remapping_alloc(struct irq_domain *domain,
irq_data->hwirq = (index << 16) + i;
irq_data->chip_data = ird;
- irq_data->chip = &intel_ir_chip;
+ irq_data->chip = posted_msi_supported() ? &intel_ir_chip_post_msi : &intel_ir_chip;
intel_irq_remapping_prepare_irte(ird, irq_cfg, info, index, i);
irq_set_status_flags(virq + i, IRQ_MOVE_PCNTXT);
}
--
2.25.1
