From: Fenghua Yu <fenghua.yu@intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
X86 ML <x86@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH RFC V2 17/17] x86/entry: Preserve PKRS MSR across exceptions
Date: Thu, 23 Jul 2020 09:52:04 -0700 [thread overview]
Message-ID: <20200723165204.GB77434@romley-ivt3.sc.intel.com> (raw)
In-Reply-To: <1cdb358b-861a-5f74-8cd0-84ee5265035c@intel.com>
Hi, Dave,
On Thu, Jul 23, 2020 at 09:23:13AM -0700, Dave Hansen wrote:
> On 7/23/20 9:18 AM, Fenghua Yu wrote:
> > The PKRS MSR has been preserved in thread_info during kernel entry. We
> > don't need to preserve it in another place (i.e. idtentry_state).
>
> I'm missing how the PKRS MSR gets preserved in thread_info. Could you
> explain the mechanism by which this happens and point to the code
> implementing it, please?
[Sorry, my mistake: I mean "thread_struct" instead of "thread_info".
Hopefully the typo doesn't change the essential part in my last email.]
The "saved_pkrs" is defined in thread_struct and context switched in
patch 04/17:
https://lore.kernel.org/lkml/20200717072056.73134-5-ira.weiny@intel.com/
Because there is no XSAVE support the PKRS MSR, we preserve it in
"saved_pkrs" in thread_struct. It's initialized as 0 (init state, no
protection key) in fork() or exec(). It's updated to a right protection
value when a driver calls the updating API. The PKRS MSR is context
switched by "saved_pkrs" when switching to a task (unless optimized if the
cached MSR is the same as the saved one).
Thanks.
-Fenghua
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WARNING: multiple messages have this Message-ID (diff)
From: Fenghua Yu <fenghua.yu@intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Weiny Ira <ira.weiny@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
X86 ML <x86@kernel.org>, Dan Williams <dan.j.williams@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH RFC V2 17/17] x86/entry: Preserve PKRS MSR across exceptions
Date: Thu, 23 Jul 2020 09:52:04 -0700 [thread overview]
Message-ID: <20200723165204.GB77434@romley-ivt3.sc.intel.com> (raw)
In-Reply-To: <1cdb358b-861a-5f74-8cd0-84ee5265035c@intel.com>
Hi, Dave,
On Thu, Jul 23, 2020 at 09:23:13AM -0700, Dave Hansen wrote:
> On 7/23/20 9:18 AM, Fenghua Yu wrote:
> > The PKRS MSR has been preserved in thread_info during kernel entry. We
> > don't need to preserve it in another place (i.e. idtentry_state).
>
> I'm missing how the PKRS MSR gets preserved in thread_info. Could you
> explain the mechanism by which this happens and point to the code
> implementing it, please?
[Sorry, my mistake: I mean "thread_struct" instead of "thread_info".
Hopefully the typo doesn't change the essential part in my last email.]
The "saved_pkrs" is defined in thread_struct and context switched in
patch 04/17:
https://lore.kernel.org/lkml/20200717072056.73134-5-ira.weiny@intel.com/
Because there is no XSAVE support the PKRS MSR, we preserve it in
"saved_pkrs" in thread_struct. It's initialized as 0 (init state, no
protection key) in fork() or exec(). It's updated to a right protection
value when a driver calls the updating API. The PKRS MSR is context
switched by "saved_pkrs" when switching to a task (unless optimized if the
cached MSR is the same as the saved one).
Thanks.
-Fenghua
WARNING: multiple messages have this Message-ID (diff)
From: Fenghua Yu <fenghua.yu@intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Weiny Ira <ira.weiny@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
X86 ML <x86@kernel.org>, Dan Williams <dan.j.williams@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH RFC V2 17/17] x86/entry: Preserve PKRS MSR across exceptions
Date: Thu, 23 Jul 2020 09:52:04 -0700 [thread overview]
Message-ID: <20200723165204.GB77434@romley-ivt3.sc.intel.com> (raw)
In-Reply-To: <1cdb358b-861a-5f74-8cd0-84ee5265035c@intel.com>
Hi, Dave,
On Thu, Jul 23, 2020 at 09:23:13AM -0700, Dave Hansen wrote:
> On 7/23/20 9:18 AM, Fenghua Yu wrote:
> > The PKRS MSR has been preserved in thread_info during kernel entry. We
> > don't need to preserve it in another place (i.e. idtentry_state).
>
> I'm missing how the PKRS MSR gets preserved in thread_info. Could you
> explain the mechanism by which this happens and point to the code
> implementing it, please?
[Sorry, my mistake: I mean "thread_struct" instead of "thread_info".
Hopefully the typo doesn't change the essential part in my last email.]
The "saved_pkrs" is defined in thread_struct and context switched in
patch 04/17:
https://lore.kernel.org/lkml/20200717072056.73134-5-ira.weiny@intel.com/
Because there is no XSAVE support the PKRS MSR, we preserve it in
"saved_pkrs" in thread_struct. It's initialized as 0 (init state, no
protection key) in fork() or exec(). It's updated to a right protection
value when a driver calls the updating API. The PKRS MSR is context
switched by "saved_pkrs" when switching to a task (unless optimized if the
cached MSR is the same as the saved one).
Thanks.
-Fenghua
next prev parent reply other threads:[~2020-07-23 16:52 UTC|newest]
Thread overview: 157+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-17 7:20 [PATCH RFC V2 00/17] PKS: Add Protection Keys Supervisor (PKS) support ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 01/17] x86/pkeys: Create pkeys_internal.h ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 02/17] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 8:54 ` Peter Zijlstra
2020-07-17 8:54 ` Peter Zijlstra
2020-07-17 20:52 ` Ira Weiny
2020-07-17 20:52 ` Ira Weiny
2020-07-20 9:14 ` Peter Zijlstra
2020-07-20 9:14 ` Peter Zijlstra
2020-07-17 22:36 ` Dave Hansen
2020-07-17 22:36 ` Dave Hansen
2020-07-20 9:13 ` Peter Zijlstra
2020-07-20 9:13 ` Peter Zijlstra
2020-07-17 7:20 ` [PATCH RFC V2 03/17] x86/pks: Enable Protection Keys Supervisor (PKS) ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 04/17] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 8:31 ` Peter Zijlstra
2020-07-17 8:31 ` Peter Zijlstra
2020-07-17 21:39 ` Ira Weiny
2020-07-17 21:39 ` Ira Weiny
2020-07-17 8:59 ` Peter Zijlstra
2020-07-17 8:59 ` Peter Zijlstra
2020-07-17 22:34 ` Ira Weiny
2020-07-17 22:34 ` Ira Weiny
2020-07-20 9:15 ` Peter Zijlstra
2020-07-20 9:15 ` Peter Zijlstra
2020-07-20 18:35 ` Ira Weiny
2020-07-20 18:35 ` Ira Weiny
2020-07-17 7:20 ` [PATCH RFC V2 05/17] x86/pks: Add PKS kernel API ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 06/17] x86/pks: Add a debugfs file for allocated PKS keys ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 07/17] Documentation/pkeys: Update documentation for kernel pkeys ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 08/17] x86/pks: Add PKS Test code ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 09/17] memremap: Convert devmap static branch to {inc,dec} ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 10/17] fs/dax: Remove unused size parameter ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 11/17] drivers/dax: Expand lock scope to cover the use of addresses ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 12/17] memremap: Add zone device access protection ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 9:10 ` Peter Zijlstra
2020-07-17 9:10 ` Peter Zijlstra
2020-07-18 5:06 ` Ira Weiny
2020-07-18 5:06 ` Ira Weiny
2020-07-20 9:16 ` Peter Zijlstra
2020-07-20 9:16 ` Peter Zijlstra
2020-07-17 9:17 ` Peter Zijlstra
2020-07-17 9:17 ` Peter Zijlstra
2020-07-18 5:51 ` Ira Weiny
2020-07-18 5:51 ` Ira Weiny
2020-07-17 9:20 ` Peter Zijlstra
2020-07-17 9:20 ` Peter Zijlstra
2020-07-17 7:20 ` [PATCH RFC V2 13/17] kmap: Add stray write protection for device pages ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 9:21 ` Peter Zijlstra
2020-07-17 9:21 ` Peter Zijlstra
2020-07-19 4:13 ` Ira Weiny
2020-07-19 4:13 ` Ira Weiny
2020-07-20 9:17 ` Peter Zijlstra
2020-07-20 9:17 ` Peter Zijlstra
2020-07-21 16:31 ` Ira Weiny
2020-07-21 16:31 ` Ira Weiny
2020-07-17 7:20 ` [PATCH RFC V2 14/17] dax: Stray write protection for dax_direct_access() ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 9:22 ` Peter Zijlstra
2020-07-17 9:22 ` Peter Zijlstra
2020-07-19 4:41 ` Ira Weiny
2020-07-19 4:41 ` Ira Weiny
2020-07-17 7:20 ` [PATCH RFC V2 15/17] nvdimm/pmem: Stray write protection for pmem->virt_addr ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 7:20 ` [PATCH RFC V2 16/17] [dax|pmem]: Enable stray write protection ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 9:25 ` Peter Zijlstra
2020-07-17 9:25 ` Peter Zijlstra
2020-07-17 7:20 ` [PATCH RFC V2 17/17] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2020-07-17 7:20 ` ira.weiny
2020-07-17 9:30 ` Peter Zijlstra
2020-07-17 9:30 ` Peter Zijlstra
2020-07-21 18:01 ` Ira Weiny
2020-07-21 18:01 ` Ira Weiny
2020-07-21 19:11 ` Peter Zijlstra
2020-07-21 19:11 ` Peter Zijlstra
2020-07-17 9:34 ` Peter Zijlstra
2020-07-17 9:34 ` Peter Zijlstra
2020-07-17 10:06 ` Peter Zijlstra
2020-07-17 10:06 ` Peter Zijlstra
2020-07-22 5:27 ` Ira Weiny
2020-07-22 5:27 ` Ira Weiny
2020-07-22 9:48 ` Peter Zijlstra
2020-07-22 9:48 ` Peter Zijlstra
2020-07-22 21:24 ` Ira Weiny
2020-07-22 21:24 ` Ira Weiny
2020-07-23 20:08 ` Thomas Gleixner
2020-07-23 20:08 ` Thomas Gleixner
2020-07-23 20:15 ` Thomas Gleixner
2020-07-23 20:15 ` Thomas Gleixner
2020-07-24 17:23 ` Ira Weiny
2020-07-24 17:23 ` Ira Weiny
2020-07-24 17:29 ` Andy Lutomirski
2020-07-24 17:29 ` Andy Lutomirski
2020-07-24 19:43 ` Ira Weiny
2020-07-24 19:43 ` Ira Weiny
2020-07-22 16:21 ` Andy Lutomirski
2020-07-22 16:21 ` Andy Lutomirski
2020-07-22 16:21 ` Andy Lutomirski
2020-07-23 16:18 ` Fenghua Yu
2020-07-23 16:18 ` Fenghua Yu
2020-07-23 16:18 ` Fenghua Yu
2020-07-23 16:23 ` Dave Hansen
2020-07-23 16:23 ` Dave Hansen
2020-07-23 16:23 ` Dave Hansen
2020-07-23 16:52 ` Fenghua Yu [this message]
2020-07-23 16:52 ` Fenghua Yu
2020-07-23 16:52 ` Fenghua Yu
2020-07-23 17:08 ` Andy Lutomirski
2020-07-23 17:08 ` Andy Lutomirski
2020-07-23 17:08 ` Andy Lutomirski
2020-07-23 17:30 ` Dave Hansen
2020-07-23 17:30 ` Dave Hansen
2020-07-23 17:30 ` Dave Hansen
2020-07-23 20:23 ` Thomas Gleixner
2020-07-23 20:23 ` Thomas Gleixner
2020-07-23 20:23 ` Thomas Gleixner
2020-07-23 20:22 ` Thomas Gleixner
2020-07-23 20:22 ` Thomas Gleixner
2020-07-23 20:22 ` Thomas Gleixner
2020-07-23 21:30 ` Andy Lutomirski
2020-07-23 21:30 ` Andy Lutomirski
2020-07-23 21:30 ` Andy Lutomirski
2020-07-23 22:14 ` Thomas Gleixner
2020-07-23 22:14 ` Thomas Gleixner
2020-07-23 22:14 ` Thomas Gleixner
2020-07-23 19:53 ` Thomas Gleixner
2020-07-23 19:53 ` Thomas Gleixner
2020-07-23 22:04 ` Ira Weiny
2020-07-23 22:04 ` Ira Weiny
2020-07-23 23:41 ` Thomas Gleixner
2020-07-23 23:41 ` Thomas Gleixner
2020-07-24 21:24 ` Thomas Gleixner
2020-07-24 21:24 ` Thomas Gleixner
2020-07-24 21:31 ` Thomas Gleixner
2020-07-24 21:31 ` Thomas Gleixner
2020-07-25 0:09 ` Andy Lutomirski
2020-07-25 0:09 ` Andy Lutomirski
2020-07-25 0:09 ` Andy Lutomirski
2020-07-27 20:59 ` Ira Weiny
2020-07-27 20:59 ` Ira Weiny
2020-07-24 22:19 ` [PATCH RFC V2 00/17] PKS: Add Protection Keys Supervisor (PKS) support Kees Cook
2020-07-24 22:19 ` Kees Cook
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