From: Jim Mattson <jmattson@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Like Xu <like.xu.linux@gmail.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: x86/svm: Add module param to control PMU virtualization
Date: Fri, 10 Dec 2021 19:48:27 -0800 [thread overview]
Message-ID: <CALMp9eSLU1kfffC3Du58L8iPY6LmKyVO0yU7c3wEnJAD9JZw4w@mail.gmail.com> (raw)
In-Reply-To: <438d42de-78e1-0ce9-6a06-38194de4abd4@redhat.com>
On Fri, Dec 10, 2021 at 6:15 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 12/10/21 20:25, Jim Mattson wrote:
> > In the long run, I'd like to be able to override this system-wide
> > setting on a per-VM basis, for VMs that I trust. (Of course, this
> > implies that I trust the userspace process as well.)
> >
> > How would you feel if we were to add a kvm ioctl to override this
> > setting, for a particular VM, guarded by an appropriate permissions
> > check, like capable(CAP_SYS_ADMIN) or capable(CAP_SYS_MODULE)?
>
> What's the rationale for guarding this with a capability check? IIRC
> you don't have such checks for perf_event_open (apart for getting kernel
> addresses, which is not a problem for virtualization).
My reasoning was simply that for userspace to override a mode 0444
kernel module parameter, it should have the rights to reload the
module with the parameter override. I wasn't thinking specifically
about PMU capabilities.
next prev parent reply other threads:[~2021-12-11 3:57 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-17 8:03 [PATCH] KVM: x86/svm: Add module param to control PMU virtualization Like Xu
2021-11-18 13:25 ` Paolo Bonzini
2021-12-10 19:25 ` Jim Mattson
2021-12-11 2:15 ` Paolo Bonzini
2021-12-11 3:48 ` Jim Mattson [this message]
2022-01-09 1:23 ` Jim Mattson
2022-01-10 6:23 ` Like Xu
2022-01-10 18:13 ` Jim Mattson
2022-01-11 2:11 ` Like Xu
2022-01-11 3:24 ` Jim Mattson
2022-01-11 6:18 ` Like Xu
2022-01-11 7:25 ` Jim Mattson
2022-01-15 1:26 ` Jim Mattson
2022-01-17 2:33 ` Like Xu
2022-01-17 8:36 ` Paolo Bonzini
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