linux-kernel - Re: [PATCH 0/2] KVM: x86: Enhance vendor module error messages

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Message-ID: <842ca2d4-fa72-3814-6c52-e079f081ec5d@redhat.com>
Date:   Wed, 20 Oct 2021 16:55:55 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Paul Menzel <pmenzel@...gen.mpg.de>,
        "Maciej S . Szmigiero" <mail@...iej.szmigiero.name>
Subject: Re: [PATCH 0/2] KVM: x86: Enhance vendor module error messages

On 18/10/21 20:39, Sean Christopherson wrote:
> Paul Menzel encountered the bad userspace behavior of spamming KVM module
> loading on all CPUs, which was mitigated by commit ef935c25fd64 ("kvm: x86:
> Limit the number of "kvm: disabled by bios" messages"), except this time
> userspace is extra "clever" and spams both kvm_intel and kvm_amd.  Because
> the "already loaded the other module" message isn't ratelimited, the bogus
> module load managed to spam the kernel log.
> 
> Patch 1 addresses another suggestion from Paul by incorporating the vendor
> module name into the error messages.
> 
> Patch 2 addresses the original report by prioritizing the hardware/bios
> support messages over the "already loaded" error.  In additional to
> reducing spam, doing so also ensures consistent messaging if a vendor
> module isn't supported regardless of what other modules may be loaded.
> 
> [*] https://lkml.kernel.org/r/20210818114956.7171-1-pmenzel@molgen.mpg.de
> 
> Sean Christopherson (2):
>    KVM: x86: Add vendor name to kvm_x86_ops, use it for error messages
>    KVM: x86: Defer "already loaded" check until after basic support
>      checks
> 
>   arch/x86/include/asm/kvm_host.h |  2 ++
>   arch/x86/kvm/svm/svm.c          |  2 ++
>   arch/x86/kvm/vmx/vmx.c          |  2 ++
>   arch/x86/kvm/x86.c              | 17 +++++++++--------
>   4 files changed, 15 insertions(+), 8 deletions(-)
> 

Queued, thanks.  But I kept the ratelimiting; given the recent "clashes" 
with the chief penguin, I am also ratelimiting the snark in the commit 
messages.

Paolo