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[35.247.111.240]) by smtp.gmail.com with ESMTPSA id b10sm22344008pgm.76.2021.04.07.10.05.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Apr 2021 10:05:10 -0700 (PDT) Date: Wed, 7 Apr 2021 17:05:07 +0000 From: Sean Christopherson To: Borislav Petkov Cc: Christophe Leroy , Paolo Bonzini , Brijesh Singh , Tom Lendacky , John Allen , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 8/8] KVM: SVM: Allocate SEV command structures on local stack Message-ID: References: <20210406224952.4177376-1-seanjc@google.com> <20210406224952.4177376-9-seanjc@google.com> <9df3b755-d71a-bfdf-8bee-f2cd2883ea2f@csgroup.eu> <20210407102440.GA25732@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210407102440.GA25732@zn.tnic> Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Wed, Apr 07, 2021, Borislav Petkov wrote: > First of all, I'd strongly suggest you trim your emails when you reply - > that would be much appreciated. > > On Wed, Apr 07, 2021 at 07:24:54AM +0200, Christophe Leroy wrote: > > > @@ -258,7 +240,7 @@ static int sev_issue_cmd(struct kvm *kvm, int id, void *data, int *error) > > > static int sev_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) > > > { > > > struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > > > - struct sev_data_launch_start *start; > > > + struct sev_data_launch_start start; > > > > struct sev_data_launch_start start = {0, 0, 0, 0, 0, 0, 0}; > > I don't know how this is any better than using memset... > > Also, you can do > > ... start = { }; > > which is certainly the only other alternative to memset, AFAIK. > > But whatever you do, you need to look at the resulting asm the compiler > generates. So let's do that: I'm ok with Boris' version, I'm not a fan of having to count zeros. I used memset() to defer initialization until after the various sanity checks, and out of habit.