Re: [PATCH v3 02/13] KVM: SVM: Free sev_asid_bitmap during init if SEV setup fails

[Tom Lendacky]

On 1/22/21 2:21 PM, Sean Christopherson wrote:
> Free sev_asid_bitmap if the reclaim bitmap allocation fails, othwerise
> KVM will unnecessarily keep the bitmap when SEV is not fully enabled.
>
> Freeing the page is also necessary to avoid introducing a bug when a
> future patch eliminates svm_sev_enabled() in favor of using the global
> 'sev' flag directly.  While sev_hardware_enabled() checks max_sev_asid,
> which is true even if KVM setup fails, 'sev' will be true if and only
> if KVM setup fully succeeds.
>
> Fixes: 33af3a7ef9e6 ("KVM: SVM: Reduce WBINVD/DF_FLUSH invocations")
> Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>

> ---
>   arch/x86/kvm/svm/sev.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index c8ffdbc81709..ec742dabbd5b 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -1274,8 +1274,11 @@ void __init sev_hardware_setup(void)
>   		goto out;
>   
>   	sev_reclaim_asid_bitmap = bitmap_zalloc(max_sev_asid, GFP_KERNEL);
> -	if (!sev_reclaim_asid_bitmap)
> +	if (!sev_reclaim_asid_bitmap) {
> +		bitmap_free(sev_asid_bitmap);
> +		sev_asid_bitmap = NULL;
>   		goto out;
> +	}
>   
>   	pr_info("SEV supported: %u ASIDs\n", max_sev_asid - min_sev_asid + 1);
>   	sev_supported = true;