linux-kernel - Re: [PATCH v4 09/18] KVM: arm64: selftests: Add guest support to get the vcpuid

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: <20210913073512.x774i5hi3s4wmopx@gator.home>
Date:   Mon, 13 Sep 2021 09:35:12 +0200
From:   Andrew Jones <drjones@...hat.com>
To:     Reiji Watanabe <reijiw@...gle.com>
Cc:     Raghavendra Rao Ananta <rananta@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Peter Shier <pshier@...gle.com>,
        Ricardo Koller <ricarkol@...gle.com>,
        Oliver Upton <oupton@...gle.com>,
        Jing Zhang <jingzhangos@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v4 09/18] KVM: arm64: selftests: Add guest support to get
 the vcpuid

On Sun, Sep 12, 2021 at 12:05:22AM -0700, Reiji Watanabe wrote:
> Hi Raghu and all,
> 
> On Wed, Sep 8, 2021 at 6:38 PM Raghavendra Rao Ananta
> <rananta@...gle.com> wrote:
> >
> > At times, such as when in the interrupt handler, the guest wants
> > to get the vcpuid that it's running on. As a result, introduce
> > get_vcpuid() that returns the vcpuid of the calling vcpu. At its
> > backend, the VMM prepares a map of vcpuid and mpidr during VM
> > initialization and exports the map to the guest for it to read.
> 
> How about using TPIDR_EL1 to hold the vcpuid ?
> i.e. have aarch64_vcpu_setup() set the register to vcpuid and
> guest_get_vcpuid() simply return a value of the register.
> This would be a simpler solution to implement.

That is a great suggestion. It's arch-specific, but maybe the
other architectures can mimic it with their own capabilities.
And, in the unlikely event a unit test wants that register for
itself, then it can build its own mpidr-vcpuid map if necessary.
Ship it :-)

Thanks,
drew