Re: [PATCH 2/2] target/arm/hvf: set 4KB IPA granule on macOS 26

[Mohamed Mediouni <mohamed@unpredictable.fr>]

> On 9. Mar 2026, at 22:49, Lucas Amaral <lucaaamaral@gmail.com> wrote:
> 
> macOS 26 introduces hv_vm_config_set_ipa_granule() which allows
> configuring 4KB IPA granularity for HVF virtual machines.  This
> enables hv_vm_map() to accept 4KB-aligned addresses, matching
> the guest kernel's page size.
> 
> Without this, virtio-gpu blob BAR offsets that are 4KB-aligned but
> not 16KB-aligned cannot be mapped into the guest, falling back to
> slow MMIO emulation.
> 
> Gated behind MAC_OS_VERSION_26_0 compile-time and __builtin_available
> runtime checks.  Falls back to the default 16KB granule on older
> macOS versions.
> 
> Signed-off-by: Lucas Amaral <lucaaamaral@gmail.com>
> ---
> target/arm/hvf/hvf.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
> 
> diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
> index 87ddcdb..b71a98a 100644
> --- a/target/arm/hvf/hvf.c
> +++ b/target/arm/hvf/hvf.c
> @@ -960,6 +960,20 @@ hv_return_t hvf_arch_vm_create(MachineState *ms, uint32_t pa_range)
>     }
>     chosen_ipa_bit_size = pa_range;
> 
> +#ifdef MAC_OS_VERSION_26_0
> +#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_VERSION_26_0
> +    if (__builtin_available(macOS 26, *)) {
> +        ret = hv_vm_config_set_ipa_granule(config, HV_IPA_GRANULE_4KB);
> +        if (ret != HV_SUCCESS) {
> +            error_report("HVF: failed to set 4KB IPA granule: %s",
> +                         hvf_return_string(ret));
> +            goto cleanup;
> +        }
> +        hvf_set_map_granule(4096);
> +    }
> +#endif
> +#endif

Hello,

Not really happy about having this as a default… I see a double digit perf impact on compilation workloads here.
So having this as an optional, off by default option sounds best.

Thank you,
-Mohamed
> +
>     ret = hv_vm_create(config);
> 
> cleanup:
> -- 
> 2.52.0
> 
>