Ping: [PATCH] VT-d: fix !HVM build

[Jan Beulich <jbeulich@xxxxxxxx>]

On 22.04.2022 11:58, Jan Beulich wrote:
> EPT is of no interest when !HVM. While I'm observing gcc11 to fully
> eliminate the function, older gcc's DCE looks to not be as good. Aid the
> compiler in eliminating the accesses of opt_hap_{2mb,1gb}, which
> otherwise cause undefined symbol errors when linking.
> 
> While there adjust types.
> 
> Fixes: c479415610f0 ("x86/P2M: p2m.c is HVM-only")
> Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

I guess I'll put this in (as being simple enough) if I don't hear
anything back by the end of the week.

Jan

> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -2155,14 +2155,17 @@ static int cf_check intel_iommu_lookup_p
>      return 0;
>  }
>  
> -static int __init vtd_ept_page_compatible(struct vtd_iommu *iommu)
> +static bool __init vtd_ept_page_compatible(const struct vtd_iommu *iommu)
>  {
> -    u64 ept_cap, vtd_cap = iommu->cap;
> +    uint64_t ept_cap, vtd_cap = iommu->cap;
> +
> +    if ( !IS_ENABLED(CONFIG_HVM) )
> +        return false;
>  
>      /* EPT is not initialised yet, so we must check the capability in
>       * the MSR explicitly rather than use cpu_has_vmx_ept_*() */
>      if ( rdmsr_safe(MSR_IA32_VMX_EPT_VPID_CAP, ept_cap) != 0 ) 
> -        return 0;
> +        return false;
>  
>      return (ept_has_2mb(ept_cap) && opt_hap_2mb) <= cap_sps_2mb(vtd_cap) &&
>             (ept_has_1gb(ept_cap) && opt_hap_1gb) <= cap_sps_1gb(vtd_cap);
> 
>