plic, aplic: handle all pending interrupts for hart

Otherwise, we are going to take another interrupt-induced exception immediately upon execution of the sret instruction -- overall wasting cycles. Reviewed by: br MFC after: 1 week Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D47134
mhorne · Oct 30, 2024 · d584228 · d584228
1 parent 5050fdb
commit d584228
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Showing 2 changed files with 12 additions and 11 deletions.
diff --git a/sys/riscv/riscv/aplic.c b/sys/riscv/riscv/aplic.c
@@ -224,21 +224,23 @@ aplic_intr(void *arg)
 {
 	struct aplic_softc *sc;
 	struct trapframe *tf;
-	u_int claimi, prio, irq;
+	uint32_t claimi;
+	u_int prio, irq;
 	int cpu;
 
 	sc = arg;
 	cpu = PCPU_GET(cpuid);
 
-	/* Claim any pending interrupt. */
-	claimi = aplic_read(sc, APLIC_IDC_CLAIMI(sc, cpu));
-	prio = APLIC_IDC_CLAIMI_PRIO(claimi);
-	irq = APLIC_IDC_CLAIMI_IRQ(claimi);
+	/* Claim all pending interrupts. */
+	while ((claimi = aplic_read(sc, APLIC_IDC_CLAIMI(sc, cpu))) != 0) {
+		prio = APLIC_IDC_CLAIMI_PRIO(claimi);
+		irq = APLIC_IDC_CLAIMI_IRQ(claimi);
 
-	KASSERT((irq != 0), ("Invalid IRQ 0"));
+		KASSERT((irq != 0), ("Invalid IRQ 0"));
 
-	tf = curthread->td_intr_frame;
-	aplic_irq_dispatch(sc, irq, prio, tf);
+		tf = curthread->td_intr_frame;
+		aplic_irq_dispatch(sc, irq, prio, tf);
+	}
 
 	return (FILTER_HANDLED);
 }

diff --git a/sys/riscv/riscv/plic.c b/sys/riscv/riscv/plic.c
@@ -175,9 +175,8 @@ plic_intr(void *arg)
 	sc = arg;
 	cpu = PCPU_GET(cpuid);
 
-	/* Claim any pending interrupt. */
-	pending = RD4(sc, PLIC_CLAIM(sc, cpu));
-	if (pending) {
+	/* Claim all pending interrupts. */
+	while ((pending = RD4(sc, PLIC_CLAIM(sc, cpu))) != 0) {
 		tf = curthread->td_intr_frame;
 		plic_irq_dispatch(sc, pending, tf);
 	}