linux-kernel - Re: [PATCH 00/44] KVM: Rework kvm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 8 Nov 2022 08:56:58 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "isaku.yamahata@...il.com" <isaku.yamahata@...il.com>
CC:     "borntraeger@...ux.ibm.com" <borntraeger@...ux.ibm.com>,
        "Yao, Yuan" <yuan.yao@...el.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "kvm-riscv@...ts.infradead.org" <kvm-riscv@...ts.infradead.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "suzuki.poulose@....com" <suzuki.poulose@....com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "david@...hat.com" <david@...hat.com>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "kvmarm@...ts.linux.dev" <kvmarm@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mjrosato@...ux.ibm.com" <mjrosato@...ux.ibm.com>,
        "oliver.upton@...ux.dev" <oliver.upton@...ux.dev>,
        "farosas@...ux.ibm.com" <farosas@...ux.ibm.com>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "palmer@...belt.com" <palmer@...belt.com>,
        "chenhuacai@...nel.org" <chenhuacai@...nel.org>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "aou@...s.berkeley.edu" <aou@...s.berkeley.edu>,
        "alexandru.elisei@....com" <alexandru.elisei@....com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "maz@...nel.org" <maz@...nel.org>,
        "anup@...infault.org" <anup@...infault.org>,
        "frankja@...ux.ibm.com" <frankja@...ux.ibm.com>,
        "farman@...ux.ibm.com" <farman@...ux.ibm.com>,
        "james.morse@....com" <james.morse@....com>,
        "kvmarm@...ts.cs.columbia.edu" <kvmarm@...ts.cs.columbia.edu>,
        "aleksandar.qemu.devel@...il.com" <aleksandar.qemu.devel@...il.com>,
        "paul.walmsley@...ive.com" <paul.walmsley@...ive.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "atishp@...shpatra.org" <atishp@...shpatra.org>,
        "imbrenda@...ux.ibm.com" <imbrenda@...ux.ibm.com>,
        "Gao, Chao" <chao.gao@...el.com>
Subject: Re: [PATCH 00/44] KVM: Rework kvm_init() and hardware enabling

On Mon, 2022-11-07 at 21:43 -0800, Isaku Yamahata wrote:
> On Tue, Nov 08, 2022 at 01:09:27AM +0000,
> "Huang, Kai" <kai.huang@...el.com> wrote:
> 
> > On Mon, 2022-11-07 at 13:46 -0800, Isaku Yamahata wrote:
> > > > On Fri, Nov 04, 2022, Isaku Yamahata wrote:
> > > > > Thanks for the patch series. I the rebased TDX KVM patch series and it
> > > > > worked.
> > > > > Since cpu offline needs to be rejected in some cases(To keep at least one
> > > > > cpu
> > > > > on a package), arch hook for cpu offline is needed.
> > > > 
> > > > I hate to bring this up because I doubt there's a real use case for SUSPEND
> > > > with
> > > > TDX, but the CPU offline path isn't just for true offlining of CPUs.  When
> > > > the
> > > > system enters SUSPEND, only the initiating CPU goes through
> > > > kvm_suspend()+kvm_resume(),
> > > > all responding CPUs go through CPU offline+online.  I.e. disallowing all
> > > > CPUs from
> > > > going "offline" will prevent suspending the system.
> > > 
> > > The current TDX KVM implementation disallows CPU package from offline only
> > > when
> > > TDs are running.  If no TD is running, CPU offline is allowed.  So before
> > > SUSPEND, TDs need to be killed via systemd or something.  After killing TDs,
> > > the
> > > system can enter into SUSPEND state.
> > 
> > This seems not correct.  You need one cpu for each to be online in order to
> > create TD as well, as TDH.MNG.KEY.CONFIG needs to be called on all packages,
> > correct?
> 
> That's correct. In such case, the creation of TD fails.  TD creation checks if
> at least one cpu is online on all CPU packages.  If no, error.

I think we can just always refuse to offline the last cpu for each package when
TDX is enabled.  It's simpler I guess.