linux-kernel - Re: [PATCH] x86: fix rdmsr MSR_PLATFORM

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Date:	Mon, 11 Jul 2016 09:38:37 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Wanpeng Li <kernellwp@...il.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	kvm <kvm@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	linux-acpi@...r.kernel.org, lkp@...org,
	the arch/x86 maintainers <x86@...nel.org>,
	Wanpeng Li <wanpeng.li@...mail.com>,
	Len Brown <len.brown@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Zhang Rui <rui.zhang@...el.com>, Chen Yu <yu.c.chen@...el.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Radim Krčmář <rkrcmar@...hat.com>,
	Jacob Pan <jacob.jun.pan@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86: fix rdmsr MSR_PLATFORM_INFO unsafe warning in kvm
 guest


* Wanpeng Li <kernellwp@...il.com> wrote:

> Hi Ingo, Thomas,
> 2016-06-22 9:28 GMT+08:00 Wanpeng Li <kernellwp@...il.com>:
> > From: Wanpeng Li <wanpeng.li@...mail.com>
> >
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 0 at arch/x86/mm/extable.c:50 ex_handler_rdmsr_unsafe+0x6a/0x70
> > unchecked MSR access error: RDMSR from 0xce
> > Modules linked in:
> > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.7.0-rc3+ #1
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> >  0000000000000000 ffffffff81c03ce0 ffffffff813b3eae ffffffff81c03d30
> >  0000000000000000 ffffffff81c03d20 ffffffff81067181 0000003200000001
> >  ffffffff81c03df8 ffffffff8179676c 0000000000000000 ffffffff81fcd2c0
> > Call Trace:
> >  dump_stack+0x67/0x99
> >  __warn+0xd1/0xf0
> >  warn_slowpath_fmt+0x4f/0x60
> >  ex_handler_rdmsr_unsafe+0x6a/0x70
> >  fixup_exception+0x39/0x50
> >  do_general_protection+0x93/0x1b0
> >  general_protection+0x22/0x30
> >  ? cpu_khz_from_msr+0xd8/0x1c0
> >  native_calibrate_cpu+0x30/0x5b0
> >  tsc_init+0x2b/0x297
> >  x86_late_time_init+0xf/0x11
> >  start_kernel+0x398/0x451
> >  ? set_init_arg+0x55/0x55
> >  x86_64_start_reservations+0x2f/0x31
> >  x86_64_start_kernel+0xea/0xed
> >
> > After commit (fc141535ad8 : "x86 tsc_msr: Extend to include Intel Core
> > Architecture"), rdmsr MSR_PLATFORM_INFO is used to get maximum non-turbo
> 
> I just saw commit (fc273eeef314c : "x86 tsc_msr: Extend to include
> Intel Core Architecture") was merged in tip tree, then this patch is
> needed to fix that commit. The bug is reported by LKP several weeks
> ago, and kvm maintainer Paolo has already replied "This looks good" to
> this patch.

Applied, thanks!

	Ingo