From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Erwan Velu <erwanaliasr1@gmail.com>
Cc: Erwan Velu <e.velu@criteo.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kvm: x86: Print "disabled by bios" only once per host
Date: Fri, 14 Feb 2020 09:05:08 -0800 [thread overview]
Message-ID: <20200214170508.GB20690@linux.intel.com> (raw)
In-Reply-To: <20200214143035.607115-1-e.velu@criteo.com>
On Fri, Feb 14, 2020 at 03:30:35PM +0100, Erwan Velu wrote:
> The current behavior is to print a "disabled by bios" message per CPU thread.
> As modern CPUs can have up to 64 cores, 128 on a dual socket, and turns this
> printk to be a pretty noisy by showing up to 256 times the same line in a row.
>
> This patch offer to only print the message once per host considering the BIOS will
> disabled the feature for all sockets/cores at once and not on a per core basis.
This has come up before[*]. Using _once() doesn't fully solve the issue
when KVM is built as a module. The spam is more than likely a userspace
bug, i.e. userspace is probing KVM on every CPU.
[*] https://lkml.kernel.org/r/20190826182320.9089-1-tony.luck@intel.com
> Signed-off-by: Erwan Velu <e.velu@criteo.com>
> ---
> arch/x86/kvm/x86.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index fbabb2f06273..8f0d7a09d453 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -7300,7 +7300,7 @@ int kvm_arch_init(void *opaque)
> goto out;
> }
> if (ops->disabled_by_bios()) {
> - printk(KERN_ERR "kvm: disabled by bios\n");
> + printk_once(KERN_ERR "kvm: disabled by bios\n");
> r = -EOPNOTSUPP;
> goto out;
> }
> --
> 2.24.1
>
next prev parent reply other threads:[~2020-02-14 17:05 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-14 14:30 [PATCH] kvm: x86: Print "disabled by bios" only once per host Erwan Velu
2020-02-14 17:05 ` Sean Christopherson [this message]
2020-02-18 16:28 ` Erwan Velu
2020-02-18 18:48 ` Sean Christopherson
2020-02-19 11:19 ` Erwan Velu
2020-02-19 11:32 ` Erwan Velu
2020-02-19 17:42 ` Erwan Velu
2020-02-19 16:18 ` Sean Christopherson
2020-02-19 16:53 ` Erwan Velu
2020-02-19 17:51 ` Paolo Bonzini
2020-02-19 21:52 ` Erwan Velu
2020-02-14 17:43 ` Jim Mattson
2020-02-27 18:00 ` [PATCH v2] kvm: x86: Limit the number of "kvm: disabled by bios" messages Erwan Velu
2020-02-28 10:37 ` Paolo Bonzini
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