From: Thomas Gleixner <tglx@linutronix.de>
To: Borislav Petkov <bp@alien8.de>
Cc: Feng Tang <feng.tang@intel.com>, Ingo Molnar <mingo@redhat.com>,
"H . Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
x86@kernel.org, linux-kernel@vger.kernel.org,
rui.zhang@intel.com, andi.kleen@intel.com, dave.hansen@intel.com,
len.brown@intel.com
Subject: Re: [RFC 1/2] x86/tsc: add a timer to make sure tsc_adjust is always checked
Date: Sat, 10 Apr 2021 20:43:27 +0200 [thread overview]
Message-ID: <87fszy2d68.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20210410094752.GB21691@zn.tnic>
On Sat, Apr 10 2021 at 11:47, Borislav Petkov wrote:
> On Sat, Apr 10, 2021 at 11:27:11AM +0200, Thomas Gleixner wrote:
>> On Tue, Mar 30 2021 at 16:25, Feng Tang wrote:
>> > Normally the tsc_sync will be checked every time system enters idle state,
>> > but there is still caveat that a system won't enter idle, either because
>> > it's too busy or configured purposely to not enter idle. Setup a periodic
>> > timer to make sure the check is always on.
>>
>> Bah. I really hate the fact that we don't have a knob to disable writes
>> to the TSC/TSC_ADJUST msrs. That would spare this business alltogether.
>
> We have the MSR filtering and I'd *love* to add those MSRs to a
> permanent ban list of MSRs which will never ever be written to from
> luserspace.
That's good, but what I really want is a knob which prevents BIOS/SMM
from writing to it. The only reason why BIOS ever needs to write is for
physical hotplug and perhaps for 4+ socket machines on boot. After that
every write is a bug.
Thanks,
tglx
next prev parent reply other threads:[~2021-04-10 18:43 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 8:25 [RFC 1/2] x86/tsc: add a timer to make sure tsc_adjust is always checked Feng Tang
2021-03-30 8:25 ` [RFC 2/2] x86/tsc: mark tsc reliable for qualified platforms Feng Tang
2021-04-10 9:27 ` [RFC 1/2] x86/tsc: add a timer to make sure tsc_adjust is always checked Thomas Gleixner
2021-04-10 9:47 ` Borislav Petkov
2021-04-10 12:11 ` [PATCH] x86/msr: Block writes to certain MSRs unconditionally Borislav Petkov
2021-04-10 14:51 ` Andy Lutomirski
2021-04-10 15:33 ` [PATCH -v1.1] " Borislav Petkov
2021-04-10 18:52 ` [PATCH] " Andi Kleen
2021-04-11 9:40 ` Borislav Petkov
2021-04-11 16:03 ` Andy Lutomirski
2021-04-11 16:43 ` Andi Kleen
2021-04-11 16:57 ` Andy Lutomirski
2021-04-11 17:03 ` Borislav Petkov
2021-04-11 23:21 ` Andy Lutomirski
2021-04-12 9:37 ` Borislav Petkov
2021-04-10 14:48 ` [RFC 1/2] x86/tsc: add a timer to make sure tsc_adjust is always checked Feng Tang
2021-04-10 15:38 ` Borislav Petkov
2021-04-10 18:43 ` Thomas Gleixner [this message]
2021-04-10 14:38 ` Feng Tang
2021-04-10 18:46 ` Thomas Gleixner
2021-04-11 7:21 ` Feng Tang
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