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From: Ira Weiny <ira.weiny@intel.com>
To: Kees Cook <keescook@chromium.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>,
	dave.hansen@intel.com, luto@kernel.org, peterz@infradead.org,
	linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org,
	linux-hardening@vger.kernel.org,
	kernel-hardening@lists.openwall.com, rppt@kernel.org,
	dan.j.williams@intel.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 0/9] PKS write protected page tables
Date: Wed, 5 May 2021 17:00:13 -0700	[thread overview]
Message-ID: <20210506000013.GE1068722@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <202105042253.ECBBF6B6@keescook>

On Tue, May 04, 2021 at 11:25:31PM -0700, Kees Cook wrote:
> On Tue, May 04, 2021 at 05:30:23PM -0700, Rick Edgecombe wrote:
> 
> > Performance impacts
> > ===================
> > Setting direct map permissions on whatever random page gets allocated for a 
> > page table would result in a lot of kernel range shootdowns and direct map 
> > large page shattering. So the way the PKS page table memory is created is 
> > similar to this module page clustering series[2], where a cache of pages is 
> > replenished from 2MB pages such that the direct map permissions and associated 
> > breakage is localized on the direct map. In the PKS page tables case, a PKS 
> > key is pre-applied to the direct map for pages in the cache.
> > 
> > There would be some costs of memory overhead in order to protect the direct 
> > map page tables. There would also be some extra kernel range shootdowns to 
> > replenish the cache on occasion, from setting the PKS key on the direct map of 
> > the new pages. I don’t have any actual performance data yet.
> 
> What CPU models are expected to have PKS?


Supervisor Memory Protection Keys (PKS) is a feature which is found on Intel’s
Sapphire Rapids (and later) “Scalable Processor” Server CPUs.  It will also be
available in future non-server Intel parts.

Also qemu has some support as well.

https://www.qemu.org/2021/04/30/qemu-6-0-0/

Ira

  parent reply	other threads:[~2021-05-06  0:00 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-05  0:30 Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 1/9] list: Support getting most recent element in list_lru Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 2/9] list: Support list head not in object for list_lru Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 3/9] x86/mm/cpa: Add grouped page allocations Rick Edgecombe
2021-05-05 12:08   ` Mike Rapoport
2021-05-05 13:09     ` Peter Zijlstra
2021-05-05 18:45       ` Mike Rapoport
2021-05-05 21:57         ` Edgecombe, Rick P
2021-05-09  9:39           ` Mike Rapoport
2021-05-10 19:38             ` Edgecombe, Rick P
2021-05-05  0:30 ` [PATCH RFC 4/9] mm: Explicitly zero page table lock ptr Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 5/9] x86, mm: Use cache of page tables Rick Edgecombe
2021-05-05  8:51   ` Peter Zijlstra
2021-05-05 12:09     ` Mike Rapoport
2021-05-05 13:19       ` Peter Zijlstra
2021-05-05 21:54         ` Edgecombe, Rick P
2021-05-06 17:59       ` Matthew Wilcox
2021-05-06 18:24   ` Shakeel Butt
2021-05-07 16:27     ` Edgecombe, Rick P
2021-05-05  0:30 ` [PATCH RFC 6/9] x86/mm/cpa: Add set_memory_pks() Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 7/9] x86/mm/cpa: Add perm callbacks to grouped pages Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 8/9] x86, mm: Protect page tables with PKS Rick Edgecombe
2021-05-05  0:30 ` [PATCH RFC 9/9] x86, cpa: PKS protect direct map page tables Rick Edgecombe
2021-05-05  2:03 ` [PATCH RFC 0/9] PKS write protected " Ira Weiny
2021-05-05  6:25 ` Kees Cook
2021-05-05  8:37   ` Peter Zijlstra
2021-05-05 18:38     ` Kees Cook
2021-05-05 19:51   ` Edgecombe, Rick P
2021-05-06  0:00   ` Ira Weiny [this message]
2021-05-05 11:08 ` Vlastimil Babka
2021-05-05 11:56   ` Peter Zijlstra
2021-05-05 19:46     ` Edgecombe, Rick P

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