[v3,04/22] target/riscv: Improve delivery of guest external interrupts

Commit Message

Anup Patel Oct. 23, 2021, 8:46 a.m. UTC

The guest external interrupts from an interrupt controller are
delivered only when the Guest/VM is running (i.e. V=1). This means
any guest external interrupt which is triggered while the Guest/VM
is not running (i.e. V=0) will be missed on QEMU resulting in Guest
with sluggish response to serial console input and other I/O events.

To solve this, we check and inject interrupt after setting V=1.

Signed-off-by: Anup Patel <[e-mail]>
---
 target/riscv/cpu_helper.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Patch

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index bb7ac9890b..04df3792a8 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -287,6 +287,19 @@  void riscv_cpu_set_virt_enabled(CPURISCVState *env, bool enable)
     }
 
     env->virt = set_field(env->virt, VIRT_ONOFF, enable);
+
+    if (enable) {
+       /*
+        * The guest external interrupts from an interrupt controller are
+        * delivered only when the Guest/VM is running (i.e. V=1). This means
+        * any guest external interrupt which is triggered while the Guest/VM
+        * is not running (i.e. V=0) will be missed on QEMU resulting in guest
+        * with sluggish response to serial console input and other I/O events.
+        *
+        * To solve this, we check and inject interrupt after setting V=1.
+        */
+        riscv_cpu_update_mip(env_archcpu(env), 0, 0);
+    }
 }
 
 bool riscv_cpu_force_hs_excep_enabled(CPURISCVState *env)