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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Juergen Gross <JGross@suse.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Tamas K Lengyel <tamas@tklengyel.com>,
	Wei Liu <wei.liu2@citrix.com>,
	Jun Nakajima <jun.nakajima@intel.com>,
	Razvan Cojocaru <rcojocaru@bitdefender.com>,
	George Dunlap <george.dunlap@eu.citrix.com>,
	Tim Deegan <tim@xen.org>, Xen-devel <xen-devel@lists.xen.org>,
	Julien Grall <julien.grall@arm.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Jan Beulich <JBeulich@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Brian Woods <brian.woods@amd.com>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
	Paul Durrant <paul.durrant@citrix.com>
Subject: Re: [PATCH 00/14] XSA-277 followup
Date: Fri, 23 Nov 2018 16:46:00 +0100	[thread overview]
Message-ID: <20181123154600.yoqpod6n72zur7nk@mac> (raw)
In-Reply-To: <2fa9131b-d3aa-a4d4-d9a9-89c918edbd5a@citrix.com>

On Wed, Nov 21, 2018 at 09:22:25PM +0000, Andrew Cooper wrote:
[...]
> The only way I see of fixing this to teach Xen about the guests gfn
> layout (as chosen by the domainbuilder), and include within that "space
> which definitely doesn't have anything in, and is safe to put shared
> mappings into".  Beyond that, we'll need some administrator level
> knowledge of which guests are safe to have XENMEM_decrease_reservation
> prohibited, or some interlocks inside Xen to disable unsafe features as
> soon as we spot a guest which isn't playing by the new rules.

I agree, this is becoming quite cumbersome for PVH Dom0 specially,
where Xen has to keep track of MMIO regions, emulated regions that
must not have anything else mapped in and normal RAM ranges. Since the
hypervisor doesn't keep track of the memory layout every time there's
a p2m change (ie: BAR mapping and unmapping for example) there's a lot
of logic to avoid overlaps.

Having some kind of memory map that can be used to look up what's
supposed to be in a memory region would be quite helpful IMO.

Roger.

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  parent reply	other threads:[~2018-11-23 15:46 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-21 13:21 [PATCH 00/14] XSA-277 followup Andrew Cooper
2018-11-21 13:21 ` [PATCH 01/14] x86/soft-reset: Drop gfn reference after calling get_gfn_query() Andrew Cooper
2018-11-22 14:45   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 02/14] x86/mem-sharing: Don't leave the altp2m lock held when nominating a page Andrew Cooper
2018-11-21 16:56   ` Tamas K Lengyel
2018-11-22 14:46   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 03/14] AMD/IOMMU: Fix multiple reference counting errors Andrew Cooper
2018-11-22 14:51   ` Jan Beulich
2018-11-22 17:46     ` Andrew Cooper
2018-11-23  8:23       ` Jan Beulich
2018-11-23 16:03         ` Andrew Cooper
2018-11-26  9:05           ` Jan Beulich
2019-01-31 15:59   ` Woods, Brian
2018-11-21 13:21 ` [PATCH 04/14] x86/p2m: Fix locking in p2m_altp2m_lazy_copy() Andrew Cooper
2018-11-21 13:59   ` Razvan Cojocaru
2018-11-22 15:01   ` Jan Beulich
2018-12-05 19:53     ` Andrew Cooper
2018-11-21 13:21 ` [PATCH 05/14] x86/p2m: Don't overwrite p2m_altp2m_lazy_copy()'s callers p2m pointer Andrew Cooper
2018-11-21 14:07   ` Razvan Cojocaru
2018-11-22 15:03   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 06/14] x86/hvm: Make the altp2m locking easier to follow Andrew Cooper
2018-11-21 14:43   ` Razvan Cojocaru
2018-11-22 15:08   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 07/14] x86/p2m: Coding style cleanup Andrew Cooper
2018-11-22 15:12   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 08/14] xen/memory: Drop ARM put_gfn() stub Andrew Cooper
2018-11-22 14:07   ` Julien Grall
2018-11-22 15:15   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 09/14] x86/p2m: Switch the two_gfns infrastructure to using gfn_t Andrew Cooper
2018-11-21 17:06   ` Tamas K Lengyel
2018-11-22 15:17   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 10/14] x86/mm: Switch {get, put}_gfn() " Andrew Cooper
2018-11-21 14:48   ` Razvan Cojocaru
2018-11-21 16:12   ` Paul Durrant
2018-11-22 15:34   ` Jan Beulich
2018-11-23  2:58   ` Tian, Kevin
2018-11-26 15:51   ` Woods, Brian
2018-11-21 13:21 ` [PATCH 11/14] xen/mm: Switch mfn_to_virt()/virt_to_mfn() to using mfn_t Andrew Cooper
2018-11-22 14:32   ` Julien Grall
2018-11-22 15:44   ` Jan Beulich
2018-11-22 15:49     ` Andrew Cooper
2018-11-21 13:21 ` [PATCH 12/14] xen/gnttab: Drop gnttab_create_{shared, status}_page() Andrew Cooper
2018-11-22 14:35   ` Julien Grall
2018-11-22 15:47   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 13/14] xen/gnttab: Simplify gnttab_map_frame() Andrew Cooper
2018-11-22 14:36   ` Julien Grall
2018-11-22 15:48   ` Jan Beulich
2018-11-21 13:21 ` [PATCH 14/14] xen/gnttab: Minor improvements to arch header files Andrew Cooper
2018-11-22 15:51   ` Jan Beulich
2018-11-22 17:56   ` Andrew Cooper
2019-01-30 20:04     ` Julien Grall
2019-01-30 20:05       ` Andrew Cooper
2018-11-21 17:19 ` [PATCH 00/14] XSA-277 followup Tamas K Lengyel
2018-11-21 21:22   ` Andrew Cooper
2018-11-21 22:42     ` Tamas K Lengyel
2018-11-22  0:08       ` Andrew Cooper
2018-11-26 17:48         ` Tamas K Lengyel
2018-11-23 15:46     ` Roger Pau Monné [this message]
2019-01-30 18:36 ` Pings for 4.12 " Andrew Cooper

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