linux-kernel - Re: [RFC Part2 PATCH v3 18/26] KVM: SVM: Add support for SEV LAUNCH

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Date:   Thu, 14 Sep 2017 12:24:44 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Brijesh Singh <brijesh.singh@....com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Joerg Roedel <joro@...tes.org>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        \"Radim Krčmář\" <rkrcmar@...hat.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [RFC Part2 PATCH v3 18/26] KVM: SVM: Add support for SEV
 LAUNCH_FINISH command

On Mon, Jul 24, 2017 at 03:02:55PM -0500, Brijesh Singh wrote:
> The command is used for finializing the SEV guest launch process.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> ---
>  arch/x86/kvm/svm.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 9b672eb..7a77197 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -6005,6 +6005,25 @@ static int sev_launch_measure(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  	return ret;
>  }
>  
> +static int sev_launch_finish(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> +	struct sev_data_launch_finish *data;

This one is a very good example why you should do this on the stack:
this struct has a single u32 handle; member. The amount of operations to
do kzalloc and kfree for a single u32 are simply not justified.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--