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From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "linux-mm@kvack.org" <linux-mm@kvack.org>,
	"rppt@kernel.org" <rppt@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"keescook@chromium.org" <keescook@chromium.org>,
	"Weiny, Ira" <ira.weiny@intel.com>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"vbabka@suse.cz" <vbabka@suse.cz>,
	"x86@kernel.org" <x86@kernel.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"rppt@linux.ibm.com" <rppt@linux.ibm.com>,
	"Lutomirski, Andy" <luto@kernel.org>
Subject: Re: [RFC PATCH 4/4] x86/mm: write protect (most) page tables
Date: Mon, 23 Aug 2021 20:08:34 +0000	[thread overview]
Message-ID: <c572619a193f787ba24f8d2658ae92dcc0734d4f.camel@intel.com> (raw)
In-Reply-To: <20210823132513.15836-5-rppt@kernel.org>

On Mon, 2021-08-23 at 16:25 +0300, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> Allocate page table using __GFP_PTE_MAPPED so that they will have 4K
> PTEs
> in the direct map. This allows to switch _PAGE_RW bit each time a
> page
> table page needs to be made writable or read-only.
> 
> The writability of the page tables is toggled only in the lowest
> level page
> table modifiction functions and immediately switched off.
> 
> The page tables created early in the boot (including the direct map
> page
> table) are not write protected.
> 
> Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
I have a second version of the PKS tables series that I think gets all
of them.

Also, I didn't see any flush anywhere when toggling. I guess the
spurious kernel fault handler is doing the work? It might be better to
just do a local flush of the address.


  reply	other threads:[~2021-08-23 20:08 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23 13:25 [RFC PATCH 0/4] mm/page_alloc: cache pte-mapped allocations Mike Rapoport
2021-08-23 13:25 ` [RFC PATCH 1/4] list: Support getting most recent element in list_lru Mike Rapoport
2021-08-23 13:25 ` [RFC PATCH 2/4] list: Support list head not in object for list_lru Mike Rapoport
2021-08-23 13:25 ` [RFC PATCH 3/4] mm/page_alloc: introduce __GFP_PTE_MAPPED flag to allocate pte-mapped pages Mike Rapoport
2021-08-23 20:29   ` Edgecombe, Rick P
2021-08-24 13:02     ` Mike Rapoport
2021-08-24 16:38       ` Edgecombe, Rick P
2021-08-24 16:54         ` Mike Rapoport
2021-08-24 17:23           ` Edgecombe, Rick P
2021-08-24 17:37             ` Mike Rapoport
2021-08-24 16:12   ` Vlastimil Babka
2021-08-25  8:43   ` David Hildenbrand
2021-08-23 13:25 ` [RFC PATCH 4/4] x86/mm: write protect (most) page tables Mike Rapoport
2021-08-23 20:08   ` Edgecombe, Rick P [this message]
2021-08-23 23:50   ` Dave Hansen
2021-08-24  3:34     ` Andy Lutomirski
2021-08-25 14:59       ` Dave Hansen
2021-08-24 13:32     ` Mike Rapoport
2021-08-25  8:38     ` David Hildenbrand
2021-08-26  8:02     ` Mike Rapoport
2021-08-26  9:01       ` Vlastimil Babka
     [not found]   ` <FB6C09CD-9CEA-4FE8-B179-98DB63EBDD68@gmail.com>
2021-08-24  5:34     ` Nadav Amit
2021-08-24 13:36       ` Mike Rapoport
2021-08-23 20:02 ` [RFC PATCH 0/4] mm/page_alloc: cache pte-mapped allocations Edgecombe, Rick P
2021-08-24 13:03   ` Mike Rapoport
2021-08-24 16:09 ` Vlastimil Babka
2021-08-29  7:06   ` Mike Rapoport

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