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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Steven Sistare <steven.sistare@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Anthony Yznaga <anthony.yznaga@oracle.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	mhocko@kernel.org, tglx@linutronix.de, mingo@redhat.com,
	bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
	arnd@arndb.de, keescook@chromium.org, gerg@linux-m68k.org,
	ktkhai@virtuozzo.com, christian.brauner@ubuntu.com,
	peterz@infradead.org, esyr@redhat.com, christian@kellner.me,
	areber@redhat.com, cyphar@cyphar.com
Subject: Re: [RFC PATCH 0/5] madvise MADV_DOEXEC
Date: Fri, 31 Jul 2020 14:48:37 -0300
Message-ID: <20200731174837.GH24045@ziepe.ca> (raw)
In-Reply-To: <71ddd3c1-bb59-3e63-e137-99b88ace454d@oracle.com>

On Fri, Jul 31, 2020 at 01:15:34PM -0400, Steven Sistare wrote:
> On 7/31/2020 12:56 PM, Jason Gunthorpe wrote:
> > On Fri, Jul 31, 2020 at 12:11:52PM -0400, Steven Sistare wrote:
> >>> Your preservation-across-exec use-case might or might not need the
> >>> VMA to be mapped at the same address.  
> >>
> >> It does.  qemu registers memory with vfio which remembers the va's in kernel
> >> metadata for the device.
> > 
> > Once the memory is registered with vfio the VA doesn't matter, vfio
> > will keep the iommu pointing at the same physical pages no matter
> > where they are mapped.
> 
> Yes, but there are other code paths that compute and use offsets between va and the
> base va.  Mapping at a different va in the new process breaks vfio; I have tried it.

Maybe you could fix vfio instead of having this adventure, if vfio is
the only motivation.

Jason


  reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-27 17:11 Anthony Yznaga
2020-07-27 17:07 ` Eric W. Biederman
2020-07-27 18:00   ` Steven Sistare
2020-07-28 13:40     ` Christian Brauner
2020-07-27 17:11 ` [RFC PATCH 1/5] elf: reintroduce using MAP_FIXED_NOREPLACE for elf executable mappings Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 2/5] mm: do not assume only the stack vma exists in setup_arg_pages() Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 3/5] mm: introduce VM_EXEC_KEEP Anthony Yznaga
2020-07-28 13:38   ` Eric W. Biederman
2020-07-28 17:44     ` Anthony Yznaga
2020-07-29 13:52   ` Kirill A. Shutemov
2020-07-29 23:20     ` Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 4/5] exec, elf: require opt-in for accepting preserved mem Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 5/5] mm: introduce MADV_DOEXEC Anthony Yznaga
2020-07-28 13:22   ` Kirill Tkhai
2020-07-28 14:06     ` Steven Sistare
2020-07-28 11:34 ` [RFC PATCH 0/5] madvise MADV_DOEXEC Kirill Tkhai
2020-07-28 17:28   ` Anthony Yznaga
2020-07-28 14:23 ` Andy Lutomirski
2020-07-28 14:30   ` Steven Sistare
2020-07-30 15:22 ` Matthew Wilcox
2020-07-30 15:27   ` Christian Brauner
2020-07-30 15:34     ` Matthew Wilcox
2020-07-30 15:54       ` Christian Brauner
2020-07-31  9:12     ` Stefan Hajnoczi
2020-07-30 15:59   ` Steven Sistare
2020-07-30 17:12     ` Matthew Wilcox
2020-07-30 17:35       ` Steven Sistare
2020-07-30 17:49         ` Matthew Wilcox
2020-07-30 18:27           ` Steven Sistare
2020-07-30 21:58             ` Eric W. Biederman
2020-07-31 14:57               ` Steven Sistare
2020-07-31 15:27                 ` Matthew Wilcox
2020-07-31 16:11                   ` Steven Sistare
2020-07-31 16:56                     ` Jason Gunthorpe
2020-07-31 17:15                       ` Steven Sistare
2020-07-31 17:48                         ` Jason Gunthorpe [this message]
2020-07-31 17:55                           ` Steven Sistare
2020-07-31 17:23                     ` Matthew Wilcox
2020-08-03 15:28                 ` Eric W. Biederman
2020-08-03 15:42                   ` James Bottomley
2020-08-03 20:03                     ` Steven Sistare
     [not found]                     ` <9371b8272fd84280ae40b409b260bab3@AcuMS.aculab.com>
2020-08-04 11:13                       ` Matthew Wilcox
2020-08-03 19:29                   ` Steven Sistare
2020-07-31 19:41 ` Steven Sistare

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