From: Borislav Petkov <bp@suse.de>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Brijesh Singh <brijesh.singh@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
John Allen <john.allen@amd.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
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
Date: Wed, 7 Apr 2021 12:24:40 +0200 [thread overview]
Message-ID: <20210407102440.GA25732@zn.tnic> (raw)
In-Reply-To: <9df3b755-d71a-bfdf-8bee-f2cd2883ea2f@csgroup.eu>
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:
Your version:
# arch/x86/kvm/svm/sev.c:261: struct sev_data_launch_start _tmp = {0, 0, 0, 0, 0, 0, 0};
movq $0, 104(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
movq $0, 112(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
movq $0, 120(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
movq $0, 128(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
movl $0, 136(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
my version:
# arch/x86/kvm/svm/sev.c:261: struct sev_data_launch_start _tmp = {};
movq $0, 104(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
movq $0, 112(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
movq $0, 120(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
movq $0, 128(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
movl $0, 136(%rsp) #, MEM[(struct sev_data_launch_start *)_561]
the memset version:
# arch/x86/kvm/svm/sev.c:269: memset(&_tmp, 0, sizeof(_tmp));
#NO_APP
movq $0, 104(%rsp) #, MEM <char[1:36]> [(void *)_561]
movq $0, 112(%rsp) #, MEM <char[1:36]> [(void *)_561]
movq $0, 120(%rsp) #, MEM <char[1:36]> [(void *)_561]
movq $0, 128(%rsp) #, MEM <char[1:36]> [(void *)_561]
movl $0, 136(%rsp) #, MEM <char[1:36]> [(void *)_561]
Ok?
--
Regards/Gruss,
Boris.
SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg
next prev parent reply other threads:[~2021-04-07 10:24 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-06 22:49 [PATCH v2 0/8] ccp: KVM: SVM: Use stack for SEV command buffers Sean Christopherson
2021-04-06 22:49 ` [PATCH v2 1/8] crypto: ccp: Free SEV device if SEV init fails Sean Christopherson
2021-04-06 22:49 ` [PATCH v2 2/8] crypto: ccp: Detect and reject "invalid" addresses destined for PSP Sean Christopherson
2021-04-06 22:49 ` [PATCH v2 3/8] crypto: ccp: Reject SEV commands with mismatching command buffer Sean Christopherson
2021-04-06 22:49 ` [PATCH v2 4/8] crypto: ccp: Play nice with vmalloc'd memory for SEV command structs Sean Christopherson
2021-04-06 22:49 ` [PATCH v2 5/8] crypto: ccp: Use the stack for small SEV command buffers Sean Christopherson
2021-04-07 5:18 ` Christophe Leroy
2021-04-17 12:40 ` Paolo Bonzini
2021-04-06 22:49 ` [PATCH v2 6/8] crypto: ccp: Use the stack and common buffer for status commands Sean Christopherson
2021-04-06 22:49 ` [PATCH v2 7/8] crypto: ccp: Use the stack and common buffer for INIT command Sean Christopherson
2021-04-07 5:20 ` Christophe Leroy
2021-04-17 12:42 ` Paolo Bonzini
2021-04-06 22:49 ` [PATCH v2 8/8] KVM: SVM: Allocate SEV command structures on local stack Sean Christopherson
2021-04-07 5:24 ` Christophe Leroy
2021-04-07 10:24 ` Borislav Petkov [this message]
2021-04-07 17:05 ` Sean Christopherson
2021-04-07 17:06 ` Christophe Leroy
2021-04-07 17:34 ` Borislav Petkov
2021-04-17 12:45 ` Paolo Bonzini
2021-04-07 17:16 ` [PATCH v2 0/8] ccp: KVM: SVM: Use stack for SEV command buffers Brijesh Singh
2021-04-07 18:00 ` Tom Lendacky
2021-04-15 16:09 ` Paolo Bonzini
2021-04-15 18:15 ` Tom Lendacky
2021-04-16 0:28 ` Herbert Xu
2021-04-17 12:47 ` Paolo Bonzini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210407102440.GA25732@zn.tnic \
--to=bp@suse.de \
--cc=brijesh.singh@amd.com \
--cc=christophe.leroy@csgroup.eu \
--cc=jmattson@google.com \
--cc=john.allen@amd.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-crypto@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=seanjc@google.com \
--cc=thomas.lendacky@amd.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).