[PATCH v2 1/1] hw/intc/riscv_aplic: Fix APLIC in_clrip and clripnum write emulation

[Yong-Xuan Wang <yongxuan.wang@sifive.com>]

In the section "4.7 Precise effects on interrupt-pending bits"
of the RISC-V AIA specification defines that:

"If the source mode is Level1 or Level0 and the interrupt domain
is configured in MSI delivery mode (domaincfg.DM = 1):
The pending bit is cleared whenever the rectified input value is
low, when the interrupt is forwarded by MSI, or by a relevant
write to an in_clrip register or to clripnum."

Update the riscv_aplic_set_pending() to match the spec.

Fixes: bf31cf06eb ("hw/intc/riscv_aplic: Fix setipnum_le write emulation for APLIC MSI-mode")
Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
---
v2:
- add fixes tag (Daniel)
- follow the suggestion from https://lore.kernel.org/kvm/CAAhSdy3NmwbHY9Qef9LUeXfr0iE7wC-u0d_fHzC47PXk-MzmRg@mail.gmail.com/
  (Anup)
---
 hw/intc/riscv_aplic.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/intc/riscv_aplic.c b/hw/intc/riscv_aplic.c
index 4a262c82f078..74c82a841101 100644
--- a/hw/intc/riscv_aplic.c
+++ b/hw/intc/riscv_aplic.c
@@ -248,9 +248,12 @@ static void riscv_aplic_set_pending(RISCVAPLICState *aplic,
 
     if ((sm == APLIC_SOURCECFG_SM_LEVEL_HIGH) ||
         (sm == APLIC_SOURCECFG_SM_LEVEL_LOW)) {
-        if (!aplic->msimode || (aplic->msimode && !pending)) {
+        if (!aplic->msimode) {
             return;
         }
+        if (aplic->msimode && !pending) {
+            goto noskip_write_pending;
+        }
         if ((aplic->state[irq] & APLIC_ISTATE_INPUT) &&
             (sm == APLIC_SOURCECFG_SM_LEVEL_LOW)) {
             return;
@@ -261,6 +264,7 @@ static void riscv_aplic_set_pending(RISCVAPLICState *aplic,
         }
     }
 
+noskip_write_pending:
     riscv_aplic_set_pending_raw(aplic, irq, pending);
 }
 
-- 
2.17.1