On 2026-01-02 14:02, Mukesh Rathor wrote:
>
> v1: Add ifndef CONFIG_X86_FRED (thanks hpa)
>
It just clicked in my brain.
This must be cpu_feature_enabled() not a static #ifndef. Just because the
kernel is compiled with FRED support doesn't mean that it is *using* FRED!
-hpa
> arch/x86/kernel/cpu/mshyperv.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 579fb2c64cfd..8ef4ca6733ac 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -478,6 +478,27 @@ int hv_get_hypervisor_version(union
> hv_hypervisor_version_info *info)
> }
> EXPORT_SYMBOL_GPL(hv_get_hypervisor_version);
>
> +#ifndef CONFIG_X86_FRED
> +/*
> + * Reserve vectors hard coded in the hypervisor. If used outside, the
> hypervisor
> + * will crash or hang or break into debugger.
> + */
> +static void hv_reserve_irq_vectors(void)
> +{
> + #define HYPERV_DBG_FASTFAIL_VECTOR 0x29
> + #define HYPERV_DBG_ASSERT_VECTOR 0x2C
> + #define HYPERV_DBG_SERVICE_VECTOR 0x2D
> +
> + if (test_and_set_bit(HYPERV_DBG_ASSERT_VECTOR, system_vectors) ||
> + test_and_set_bit(HYPERV_DBG_SERVICE_VECTOR, system_vectors) ||
> + test_and_set_bit(HYPERV_DBG_FASTFAIL_VECTOR, system_vectors))
> + BUG();
> +
> + pr_info("Hyper-V:reserve vectors: %d %d %d\n", HYPERV_DBG_ASSERT_VECTOR,
> + HYPERV_DBG_SERVICE_VECTOR, HYPERV_DBG_FASTFAIL_VECTOR);
> +}
> +#endif /* CONFIG_X86_FRED */
> +
> static void __init ms_hyperv_init_platform(void)
> {
> int hv_max_functions_eax, eax;
> @@ -510,6 +531,11 @@ static void __init ms_hyperv_init_platform(void)
>
> hv_identify_partition_type();
>
> +#ifndef CONFIG_X86_FRED
> + if (hv_root_partition())
> + hv_reserve_irq_vectors();
> +#endif /* CONFIG_X86_FRED */
> +
> if (cc_platform_has(CC_ATTR_SNP_SECURE_AVIC))
> ms_hyperv.hints |= HV_DEPRECATING_AEOI_RECOMMENDED;
>
