linux-kernel - Re: [PATCH] kvm: x86: Print "disabled by bios" only once per host

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Message-ID: <646147a6-730b-0366-10db-ed74489ad11e@criteo.com>
Date:   Wed, 19 Feb 2020 17:53:48 +0100
From:   Erwan Velu <e.velu@...teo.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Erwan Velu <erwanaliasr1@...il.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kvm: x86: Print "disabled by bios" only once per host

[..]

On 19/02/2020 17:18, Sean Christopherson wrote:
> All of that being said, what about converting all of the error messages to
> pr_err_ratelimited()?  That would take the edge off this particular problem,
> wouldn't create incosistencies between error messages, and won't completely
> squash error messages in corner case scenarios on misconfigured systems.

Thanks Sean for your very detailed answer.

I've been testing the ratelimited which is far better but still prints 
12 messages.

I saw the ratelimit is on about 5 sec, I wonder if we can explicit a 
longer one for this one.

I searched around this but it doesn't seems that hacking the delay is a 
common usage.

Do you have any insights/ideas around that ?

Switching to ratelimit could be done by replacing the actual call or add 
a macro similar to  kvm_pr_unimpl() so it can be reused easily.

I can offer the patches for that.

Erwan,