linux-kernel - RE: [PATCH] arm64/kvm: Introduce feature extension for SMCCC filter

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <DB9PR08MB751167EA104871F81D7E9ECFF4BBA@DB9PR08MB7511.eurprd08.prod.outlook.com>
Date:   Tue, 21 Nov 2023 01:58:08 +0000
From:   Jianyong Wu <Jianyong.Wu@....com>
To:     Salil Mehta <salil.mehta@...wei.com>,
        Cornelia Huck <cohuck@...hat.com>
CC:     "rmk@...linux.org.uk" <rmk@...linux.org.uk>,
        Suzuki Poulose <Suzuki.Poulose@....com>,
        "oliver.upton@...ux.dev" <oliver.upton@...ux.dev>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "kvmarm@...ts.linux.dev" <kvmarm@...ts.linux.dev>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Justin He <Justin.He@....com>,
        "maz@...nel.org" <maz@...nel.org>,
        James Morse <James.Morse@....com>,
        "will@...nel.org" <will@...nel.org>
Subject: RE: [PATCH] arm64/kvm: Introduce feature extension for SMCCC filter



> -----Original Message-----
> From: Salil Mehta <salil.mehta@...wei.com>
> Sent: 2023年11月16日 22:06
> To: Cornelia Huck <cohuck@...hat.com>; Jianyong Wu
> <Jianyong.Wu@....com>; maz@...nel.org; James Morse
> <James.Morse@....com>; will@...nel.org
> Cc: rmk@...linux.org.uk; Suzuki Poulose <Suzuki.Poulose@....com>;
> oliver.upton@...ux.dev; linux-arm-kernel@...ts.infradead.org;
> kvmarm@...ts.linux.dev; linux-kernel@...r.kernel.org; Justin He
> <Justin.He@....com>; Jianyong Wu <Jianyong.Wu@....com>
> Subject: RE: [PATCH] arm64/kvm: Introduce feature extension for SMCCC filter
> 
> > From: Cornelia Huck <cohuck@...hat.com>
> > Sent: Thursday, November 16, 2023 1:09 PM
> > To: Jianyong Wu <jianyong.wu@....com>; maz@...nel.org;
> > james.morse@....com; will@...nel.org
> >
> > On Thu, Nov 16 2023, Jianyong Wu <jianyong.wu@....com> wrote:
> >
> > > 821d935c87b introduces support for userspace SMCCC filtering, but
> > > lack of a way to tell userspace if we have this feature. Add a
> > > corresponding feature extension can resolve this issue.
> > >
> > > For example, the incoming feature Vcpu Hotplug needs the SMCCC filter.
> > > As there is no way to check this feature, VMM will run into error
> > > when it calls this feature on an old kernel. It's bad for backward compatible.
> >
> > Can't you simply query via KVM_HAS_DEVICE_ATTR whether the SMCCC
> > filtering controls exist?
> 
> 
> Agreed. In fact, this is what I had earlier intended to do but deferred this change.
> As of now, RFC V2 of vCPU Hotplug series does not have this check yet while
> installing the SMCCC filters in KVM Host.
> 

Yes, we can use KVM_HAS_DEVICE_ATTR to do the check in userspace. Thanks Cornelia.

Thanks
Jianyong

> Thanks
> 
> > > Signed-off-by: Jianyong Wu <jianyong.wu@....com>
> > > ---
> > >  Documentation/virt/kvm/api.rst | 3 ++-
> > >  arch/arm64/kvm/arm.c           | 1 +
> > >  include/uapi/linux/kvm.h       | 1 +
> > >  3 files changed, 4 insertions(+), 1 deletion(-)
> > >