Emit a warning when HVF doesn't return the IPA bit length
and return -1 as "this accelerator is not usable", allowing
QEMU to try with the next one (when using '-accel hvf:tcg').

Reported-by: Ivan Krasilnikov
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2981
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/arm/virt.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 175023897a7..1d65fa471dc 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -3225,8 +3225,12 @@ static int virt_hvf_get_physical_address_range(MachineState *ms)
 {
     VirtMachineState *vms = VIRT_MACHINE(ms);
 
-    int default_ipa_size = hvf_arm_get_default_ipa_bit_size();
-    int max_ipa_size = hvf_arm_get_max_ipa_bit_size();
+    uint32_t default_ipa_size = hvf_arm_get_default_ipa_bit_size();
+    uint32_t max_ipa_size = hvf_arm_get_max_ipa_bit_size();
+    if (!default_ipa_size || !max_ipa_size) {
+        warn_report("HVF didn't report IPA bit length");
+        return -1;
+    }
 
     /* We freeze the memory map to compute the highest gpa */
     virt_set_memmap(vms, max_ipa_size);
-- 
2.51.0

On 10/28/25 06:42, Philippe Mathieu-Daudé wrote:
> Emit a warning when HVF doesn't return the IPA bit length
> and return -1 as "this accelerator is not usable", allowing
> QEMU to try with the next one (when using '-accel hvf:tcg').
> 
> Reported-by: Ivan Krasilnikov
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2981
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>   hw/arm/virt.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index 175023897a7..1d65fa471dc 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -3225,8 +3225,12 @@ static int virt_hvf_get_physical_address_range(MachineState *ms)
>   {
>       VirtMachineState *vms = VIRT_MACHINE(ms);
>   
> -    int default_ipa_size = hvf_arm_get_default_ipa_bit_size();
> -    int max_ipa_size = hvf_arm_get_max_ipa_bit_size();
> +    uint32_t default_ipa_size = hvf_arm_get_default_ipa_bit_size();
> +    uint32_t max_ipa_size = hvf_arm_get_max_ipa_bit_size();
> +    if (!default_ipa_size || !max_ipa_size) {
> +        warn_report("HVF didn't report IPA bit length");
> +        return -1;
> +    }

I suppose this goes back to the previous patch.
It might have been slightly less confusing to merge them, but the underlying questions 
about when and how this can fail remain.


r~