target/riscv/tcg: disable svnapot if satp_mode < sv39

[PATCH] target/riscv/tcg: disable svnapot if satp_mode < sv39

Posted by Daniel Henrique Barboza 2 days, 19 hours ago

We did a recent change to disable svpbmt if satp_mode < sv39 that was
discovered via a gitlab report.

This time we don't have an opened bug but the problem is similar: RISC-V
privileged ISA, chapter '"Svnapot" Extension for NAPOT Translation
Contiguity, Version 1.0' states:

"The Svnapot extension depends on the Sv39 extension."

Do the same thing with svnapot, including the user warning in case we
try to enable it without the required satp_mode:

$ ./build/qemu-system-riscv64 -M virt,dumpdtb=fdt.dtb \
     -cpu max,sv39=off,sv48=off,sv57=off,sv64=off,svnapot=on
qemu-system-riscv64: warning: svnapot requires at least satp sv39, current satp mode: none

Signed-off-by: Daniel Henrique Barboza <daniel.barboza@oss.qualcomm.com>
---
 target/riscv/tcg/tcg-cpu.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index f8b2f04a94..c3006bccb7 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -847,6 +847,16 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
                                      riscv_cpu_is_32bit(cpu)));
         }
     }
+
+    if (cpu->cfg.ext_svnapot && cpu->cfg.max_satp_mode < VM_1_10_SV39) {
+        cpu->cfg.ext_svnapot = false;
+        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_svnapot))) {
+            warn_report("svnapot requires at least satp sv39, "
+                        "current satp mode: %s",
+                        satp_mode_str(cpu->cfg.max_satp_mode,
+                                      riscv_cpu_is_32bit(cpu)));
+        }
+    }
 #endif
     /*
      * Disable isa extensions based on priv spec after we
-- 
2.43.0

Re: [PATCH] target/riscv/tcg: disable svnapot if satp_mode < sv39

Posted by Alistair 2 days, 15 hours ago

On Thu, 28 May 2026, at 7:30 AM, Daniel Henrique Barboza wrote:
> We did a recent change to disable svpbmt if satp_mode < sv39 that was
> discovered via a gitlab report.
> 
> This time we don't have an opened bug but the problem is similar: RISC-V
> privileged ISA, chapter '"Svnapot" Extension for NAPOT Translation
> Contiguity, Version 1.0' states:
> 
> "The Svnapot extension depends on the Sv39 extension."
> 
> Do the same thing with svnapot, including the user warning in case we
> try to enable it without the required satp_mode:
> 
> $ ./build/qemu-system-riscv64 -M virt,dumpdtb=fdt.dtb \
>      -cpu max,sv39=off,sv48=off,sv57=off,sv64=off,svnapot=on
> qemu-system-riscv64: warning: svnapot requires at least satp sv39, current satp mode: none
> 
> Signed-off-by: Daniel Henrique Barboza <daniel.barboza@oss.qualcomm.com>

Thanks!

Applied to riscv-to-apply.next

Alistair

> ---
> target/riscv/tcg/tcg-cpu.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
> 
> diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
> index f8b2f04a94..c3006bccb7 100644
> --- a/target/riscv/tcg/tcg-cpu.c
> +++ b/target/riscv/tcg/tcg-cpu.c
> @@ -847,6 +847,16 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
>                                       riscv_cpu_is_32bit(cpu)));
>          }
>      }
> +
> +    if (cpu->cfg.ext_svnapot && cpu->cfg.max_satp_mode < VM_1_10_SV39) {
> +        cpu->cfg.ext_svnapot = false;
> +        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_svnapot))) {
> +            warn_report("svnapot requires at least satp sv39, "
> +                        "current satp mode: %s",
> +                        satp_mode_str(cpu->cfg.max_satp_mode,
> +                                      riscv_cpu_is_32bit(cpu)));
> +        }
> +    }
> #endif
>      /*
>       * Disable isa extensions based on priv spec after we
> -- 
> 2.43.0
> 
> 
>

Re: [PATCH] target/riscv/tcg: disable svnapot if satp_mode < sv39

Posted by Alistair 2 days, 15 hours ago

On Thu, 28 May 2026, at 7:30 AM, Daniel Henrique Barboza wrote:
> We did a recent change to disable svpbmt if satp_mode < sv39 that was
> discovered via a gitlab report.
> 
> This time we don't have an opened bug but the problem is similar: RISC-V
> privileged ISA, chapter '"Svnapot" Extension for NAPOT Translation
> Contiguity, Version 1.0' states:
> 
> "The Svnapot extension depends on the Sv39 extension."
> 
> Do the same thing with svnapot, including the user warning in case we
> try to enable it without the required satp_mode:
> 
> $ ./build/qemu-system-riscv64 -M virt,dumpdtb=fdt.dtb \
>      -cpu max,sv39=off,sv48=off,sv57=off,sv64=off,svnapot=on
> qemu-system-riscv64: warning: svnapot requires at least satp sv39, current satp mode: none
> 
> Signed-off-by: Daniel Henrique Barboza <daniel.barboza@oss.qualcomm.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
> target/riscv/tcg/tcg-cpu.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
> 
> diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
> index f8b2f04a94..c3006bccb7 100644
> --- a/target/riscv/tcg/tcg-cpu.c
> +++ b/target/riscv/tcg/tcg-cpu.c
> @@ -847,6 +847,16 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
>                                       riscv_cpu_is_32bit(cpu)));
>          }
>      }
> +
> +    if (cpu->cfg.ext_svnapot && cpu->cfg.max_satp_mode < VM_1_10_SV39) {
> +        cpu->cfg.ext_svnapot = false;
> +        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_svnapot))) {
> +            warn_report("svnapot requires at least satp sv39, "
> +                        "current satp mode: %s",
> +                        satp_mode_str(cpu->cfg.max_satp_mode,
> +                                      riscv_cpu_is_32bit(cpu)));
> +        }
> +    }
> #endif
>      /*
>       * Disable isa extensions based on priv spec after we
> -- 
> 2.43.0
> 
> 
>