[PATCH 2/2] RISC-V: KVM: Fix APLIC in_clrip[x] read emulation

[Anup Patel]

The reads to APLIC in_clrip[x] registers returns rectified input values
of the interrupt sources.

A rectified input value of an interrupt source is defined by the section
"4.5.2 Source configurations (sourcecfg[1]–sourcecfg[1023])" of the
RISC-V AIA specification as:

    rectified input value = (incoming wire value) XOR (source is inverted)

Update the riscv_aplic_input() implementation to match the above.

Fixes: 74967aa208e2 ("RISC-V: KVM: Add in-kernel emulation of AIA APLIC")
Signed-off-by: Anup Patel <apatel at ventanamicro.com>
---
 arch/riscv/kvm/aia_aplic.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kvm/aia_aplic.c b/arch/riscv/kvm/aia_aplic.c
index 5e842b92dc46..b467ba5ed910 100644
--- a/arch/riscv/kvm/aia_aplic.c
+++ b/arch/riscv/kvm/aia_aplic.c
@@ -197,16 +197,31 @@ static void aplic_write_enabled(struct aplic *aplic, u32 irq, bool enabled)
 
 static bool aplic_read_input(struct aplic *aplic, u32 irq)
 {
-	bool ret;
-	unsigned long flags;
+	u32 sourcecfg, sm, raw_input, irq_inverted;
 	struct aplic_irq *irqd;
+	unsigned long flags;
+	bool ret = false;
 
 	if (!irq || aplic->nr_irqs <= irq)
 		return false;
 	irqd = &aplic->irqs[irq];
 
 	raw_spin_lock_irqsave(&irqd->lock, flags);
-	ret = (irqd->state & APLIC_IRQ_STATE_INPUT) ? true : false;
+
+	sourcecfg = irqd->sourcecfg;
+	if (sourcecfg & APLIC_SOURCECFG_D)
+		goto skip;
+
+	sm = sourcecfg & APLIC_SOURCECFG_SM_MASK;
+	if (sm == APLIC_SOURCECFG_SM_INACTIVE)
+		goto skip;
+
+	raw_input = (irqd->state & APLIC_IRQ_STATE_INPUT) ? 1 : 0;
+	irq_inverted = (sm == APLIC_SOURCECFG_SM_LEVEL_LOW ||
+			sm == APLIC_SOURCECFG_SM_EDGE_FALL) ? 1 : 0;
+	ret = !!(raw_input ^ irq_inverted);
+
+skip:
 	raw_spin_unlock_irqrestore(&irqd->lock, flags);
 
 	return ret;
-- 
2.34.1