Re: [PATCH 1/2] KVM: SVM: free sev_*asid_bitmap init if SEV init fails

[Zhi Wang]

On Tue,  4 Apr 2023 14:26:51 +0200
Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx> wrote:

> If misc_cg_set_capacity() fails for some reason then we have
> a memleak for sev_reclaim_asid_bitmap/sev_asid_bitmap. It's
> not a case right now, because misc_cg_set_capacity() just can't
> fail and check inside it is always successful.
> 
> But let's fix that for code consistency.
> 
> Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Stéphane Graber <stgraber@xxxxxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx>
> ---
>  arch/x86/kvm/svm/sev.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index c25aeb550cd9..a42536a0681a 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -2213,8 +2213,13 @@ void __init sev_hardware_setup(void)
>  	}
>  
>  	sev_asid_count = max_sev_asid - min_sev_asid + 1;
> -	if (misc_cg_set_capacity(MISC_CG_RES_SEV, sev_asid_count))
> +	if (misc_cg_set_capacity(MISC_CG_RES_SEV, sev_asid_count)) {
> +		bitmap_free(sev_reclaim_asid_bitmap);
> +		sev_reclaim_asid_bitmap = NULL;
> +		bitmap_free(sev_asid_bitmap);
> +		sev_asid_bitmap = NULL;
>  		goto out;
> +	}
>  
>  	pr_info("SEV supported: %u ASIDs\n", sev_asid_count);
>  	sev_supported = true;

It would be nice that another case can also be fixed:

        sev_es_asid_count = min_sev_asid - 1;
        if (misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count))
                goto out; /* <----HERE */

Maybe it would be a good idea to factor out an common error handling path.