Currently QEMU will continue to create the IMSIC devices and enable the
AIA extension for guest OS when the host kernel doesn't support the AIA
extension. This will cause an illegal instruction exception when the
guest OS access the AIA CSRs. Add additional checks to ensure the
guest OS only uses the IMSIC devices when the host kernel supports
the AIA extension.

Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
---
 hw/intc/riscv_imsic.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/hw/intc/riscv_imsic.c b/hw/intc/riscv_imsic.c
index dc8162c0a7c9..8c64f2c21274 100644
--- a/hw/intc/riscv_imsic.c
+++ b/hw/intc/riscv_imsic.c
@@ -375,12 +375,21 @@ static void riscv_imsic_realize(DeviceState *dev, Error **errp)
 
     /* Force select AIA feature and setup CSR read-modify-write callback */
     if (env) {
-        if (!imsic->mmode) {
-            rcpu->cfg.ext_ssaia = true;
-            riscv_cpu_set_geilen(env, imsic->num_pages - 1);
+        if (kvm_enabled()) {
+            if (!rcpu->cfg.ext_ssaia) {
+                error_report("Host machine doesn't support AIA extension. "
+                             "Do not use IMSIC as interrupt controller.");
+                exit(1);
+            }
         } else {
-            rcpu->cfg.ext_smaia = true;
+            if (!imsic->mmode) {
+                rcpu->cfg.ext_ssaia = true;
+                riscv_cpu_set_geilen(env, imsic->num_pages - 1);
+            } else {
+                rcpu->cfg.ext_smaia = true;
+            }
         }
+
         riscv_cpu_set_aia_ireg_rmw_fn(env, (imsic->mmode) ? PRV_M : PRV_S,
                                       riscv_imsic_rmw, imsic);
     }
-- 
2.17.1

On Mon, Feb 24, 2025 at 04:24:15PM +0800, Yong-Xuan Wang wrote:
> Currently QEMU will continue to create the IMSIC devices and enable the
> AIA extension for guest OS when the host kernel doesn't support the AIA
> extension. This will cause an illegal instruction exception when the
> guest OS access the AIA CSRs. Add additional checks to ensure the
> guest OS only uses the IMSIC devices when the host kernel supports
> the AIA extension.
> 
> Signed-off-by: Yong-Xuan Wang <yongxuan.wang@sifive.com>
> ---
>  hw/intc/riscv_imsic.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/intc/riscv_imsic.c b/hw/intc/riscv_imsic.c
> index dc8162c0a7c9..8c64f2c21274 100644
> --- a/hw/intc/riscv_imsic.c
> +++ b/hw/intc/riscv_imsic.c
> @@ -375,12 +375,21 @@ static void riscv_imsic_realize(DeviceState *dev, Error **errp)
>  
>      /* Force select AIA feature and setup CSR read-modify-write callback */
>      if (env) {
> -        if (!imsic->mmode) {
> -            rcpu->cfg.ext_ssaia = true;
> -            riscv_cpu_set_geilen(env, imsic->num_pages - 1);
> +        if (kvm_enabled()) {
> +            if (!rcpu->cfg.ext_ssaia) {
> +                error_report("Host machine doesn't support AIA extension. "
> +                             "Do not use IMSIC as interrupt controller.");
> +                exit(1);
> +            }
>          } else {
> -            rcpu->cfg.ext_smaia = true;
> +            if (!imsic->mmode) {
> +                rcpu->cfg.ext_ssaia = true;
> +                riscv_cpu_set_geilen(env, imsic->num_pages - 1);
> +            } else {
> +                rcpu->cfg.ext_smaia = true;
> +            }
>          }
> +
>          riscv_cpu_set_aia_ireg_rmw_fn(env, (imsic->mmode) ? PRV_M : PRV_S,
>                                        riscv_imsic_rmw, imsic);
>      }
> -- 
> 2.17.1
> 
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>