From: Julien Grall <julien.grall@arm.com>
To: Tamas K Lengyel <tamas.k.lengyel@gmail.com>
Cc: Sergej Proskurin <proskurin@sec.in.tum.de>,
Stefano Stabellini <sstabellini@kernel.org>,
Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v2 01/25] arm/altp2m: Add first altp2m HVMOP stubs.
Date: Fri, 12 Aug 2016 10:10:22 +0200 [thread overview]
Message-ID: <3b162445-65db-03b8-7e0b-d72435a0852b@arm.com> (raw)
In-Reply-To: <CABfawhm8_ce2FzKXVjSfVT-3yz9zOguKYJ+0WPGWMB=1mhE8OQ@mail.gmail.com>
On 11/08/2016 16:41, Tamas K Lengyel wrote:
> On Aug 11, 2016 02:18, "Julien Grall" <julien.grall@arm.com
> <mailto:julien.grall@arm.com>> wrote:
>>
>> Hello Tamas,
>>
>>
>> On 10/08/2016 16:49, Tamas K Lengyel wrote:
>>>
>>> On Aug 10, 2016 03:52, "Julien Grall" <julien.grall@arm.com
> <mailto:julien.grall@arm.com>
>>> <mailto:julien.grall@arm.com <mailto:julien.grall@arm.com>>> wrote:
>>>>
>>>> On 09/08/2016 21:16, Tamas K Lengyel wrote:
>>>>>
>>>>> On Wed, Aug 3, 2016 at 10:54 AM, Julien Grall <julien.grall@arm.com
> <mailto:julien.grall@arm.com>
>>>
>>> <mailto:julien.grall@arm.com <mailto:julien.grall@arm.com>>> wrote:
>>>>>
>>>>> There is a rcu_lock_domain_by_any_id before we get to this check here,
>>>>> so any other CPU looking to disable altp2m would be waiting there for
>>>>> the current op to finish up, so there is no race condition AFAICT.
>>>>
>>>>
>>>>
>>>> No, rcu_lock_domain_by_any_id only prevents the domain to be fully
>>>
>>> destroyed by "locking" the rcu. It does not prevent multiple concurrent
>>> access. You can look at the code if you are not convinced.
>>>>
>>>>
>>>
>>> Ah thanks for clarifying. Then indeed there could be concurrency issues
>>> if there are multiple tools accessing this interface. Normally that
>>> doesn't happen though but probably a good idea to enforce it anyway.
>>
>>
>> Well, you need to think about the worst case scenario when you
> implement an interface. If you don't lock properly, the state in Xen may
> be corrupted. For instance Xen may think altp2m is active whilst it is
> not properly initialized.
>>
>
> Sure. We largely followed the x86 implementation here and there aren't
> any hvmops there that do synchronization like that, only the rcu lock is
> taken. Adding a domain_lock() should be fine though.
I would be curious to know why the x86 implementation does not need this
lock.
Cheers,
--
Julien Grall
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next prev parent reply other threads:[~2016-08-12 8:10 UTC|newest]
Thread overview: 159+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-01 17:10 [PATCH v2 00/25] arm/altp2m: Introducing altp2m to ARM Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 01/25] arm/altp2m: Add first altp2m HVMOP stubs Sergej Proskurin
2016-08-03 16:54 ` Julien Grall
2016-08-04 16:01 ` Sergej Proskurin
2016-08-04 16:04 ` Julien Grall
2016-08-04 16:22 ` Sergej Proskurin
2016-08-04 16:51 ` Julien Grall
2016-08-05 6:55 ` Sergej Proskurin
2016-08-09 19:16 ` Tamas K Lengyel
2016-08-10 9:52 ` Julien Grall
2016-08-10 14:49 ` Tamas K Lengyel
2016-08-11 8:17 ` Julien Grall
2016-08-11 14:41 ` Tamas K Lengyel
2016-08-12 8:10 ` Julien Grall [this message]
2016-08-01 17:10 ` [PATCH v2 02/25] arm/altp2m: Add HVMOP_altp2m_get_domain_state Sergej Proskurin
2016-08-01 17:21 ` Andrew Cooper
2016-08-01 17:34 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 03/25] arm/altp2m: Add struct vttbr Sergej Proskurin
2016-08-03 17:04 ` Julien Grall
2016-08-03 17:05 ` Julien Grall
2016-08-04 16:11 ` Sergej Proskurin
2016-08-04 16:15 ` Julien Grall
2016-08-06 8:54 ` Sergej Proskurin
2016-08-06 13:20 ` Julien Grall
2016-08-06 13:48 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 04/25] arm/altp2m: Move hostp2m init/teardown to individual functions Sergej Proskurin
2016-08-03 17:40 ` Julien Grall
2016-08-05 7:26 ` Sergej Proskurin
2016-08-05 9:16 ` Julien Grall
2016-08-06 8:43 ` Sergej Proskurin
2016-08-06 13:26 ` Julien Grall
2016-08-06 13:50 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 05/25] arm/altp2m: Rename and extend p2m_alloc_table Sergej Proskurin
2016-08-03 17:57 ` Julien Grall
2016-08-06 8:57 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 06/25] arm/altp2m: Cosmetic fixes - function prototypes Sergej Proskurin
2016-08-03 18:02 ` Julien Grall
2016-08-06 9:00 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 07/25] arm/altp2m: Add altp2m init/teardown routines Sergej Proskurin
2016-08-03 18:12 ` Julien Grall
2016-08-05 6:53 ` Sergej Proskurin
2016-08-05 9:20 ` Julien Grall
2016-08-06 8:30 ` Sergej Proskurin
2016-08-09 9:44 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 08/25] arm/altp2m: Add HVMOP_altp2m_set_domain_state Sergej Proskurin
2016-08-03 18:41 ` Julien Grall
2016-08-06 9:03 ` Sergej Proskurin
2016-08-06 9:36 ` Sergej Proskurin
2016-08-06 14:18 ` Julien Grall
2016-08-06 14:21 ` Julien Grall
2016-08-11 9:08 ` Julien Grall
2016-08-01 17:10 ` [PATCH v2 09/25] arm/altp2m: Add altp2m table flushing routine Sergej Proskurin
2016-08-03 18:44 ` Julien Grall
2016-08-06 9:45 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 10/25] arm/altp2m: Add HVMOP_altp2m_create_p2m Sergej Proskurin
2016-08-03 18:48 ` Julien Grall
2016-08-06 9:46 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 11/25] arm/altp2m: Add HVMOP_altp2m_destroy_p2m Sergej Proskurin
2016-08-04 11:46 ` Julien Grall
2016-08-06 9:54 ` Sergej Proskurin
2016-08-06 13:36 ` Julien Grall
2016-08-06 13:51 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 12/25] arm/altp2m: Add HVMOP_altp2m_switch_p2m Sergej Proskurin
2016-08-04 11:51 ` Julien Grall
2016-08-06 10:13 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 13/25] arm/altp2m: Make p2m_restore_state ready for altp2m Sergej Proskurin
2016-08-04 11:55 ` Julien Grall
2016-08-06 10:20 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 14/25] arm/altp2m: Make get_page_from_gva " Sergej Proskurin
2016-08-04 11:59 ` Julien Grall
2016-08-06 10:38 ` Sergej Proskurin
2016-08-06 13:45 ` Julien Grall
2016-08-06 16:58 ` Sergej Proskurin
2016-08-11 8:33 ` Julien Grall
2016-08-01 17:10 ` [PATCH v2 15/25] arm/altp2m: Extend __p2m_lookup Sergej Proskurin
2016-08-04 12:04 ` Julien Grall
2016-08-06 10:44 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 16/25] arm/altp2m: Make p2m_mem_access_check ready for altp2m Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 17/25] arm/altp2m: Cosmetic fixes - function prototypes Sergej Proskurin
2016-08-04 12:06 ` Julien Grall
2016-08-06 10:46 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 18/25] arm/altp2m: Add HVMOP_altp2m_set_mem_access Sergej Proskurin
2016-08-04 14:19 ` Julien Grall
2016-08-06 11:03 ` Sergej Proskurin
2016-08-06 14:26 ` Julien Grall
2016-08-01 17:10 ` [PATCH v2 19/25] arm/altp2m: Add altp2m_propagate_change Sergej Proskurin
2016-08-04 14:50 ` Julien Grall
2016-08-06 11:26 ` Sergej Proskurin
2016-08-06 13:52 ` Julien Grall
2016-08-06 17:06 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 20/25] arm/altp2m: Add altp2m paging mechanism Sergej Proskurin
2016-08-04 13:50 ` Julien Grall
2016-08-06 12:51 ` Sergej Proskurin
2016-08-06 14:14 ` Julien Grall
2016-08-06 17:28 ` Sergej Proskurin
2016-08-04 16:59 ` Julien Grall
2016-08-06 12:57 ` Sergej Proskurin
2016-08-06 14:21 ` Julien Grall
2016-08-06 17:35 ` Sergej Proskurin
2016-08-10 9:32 ` Sergej Proskurin
2016-08-11 8:47 ` Julien Grall
2016-08-11 17:13 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 21/25] arm/altp2m: Add HVMOP_altp2m_change_gfn Sergej Proskurin
2016-08-04 14:04 ` Julien Grall
2016-08-06 13:45 ` Sergej Proskurin
2016-08-06 14:34 ` Julien Grall
2016-08-06 17:42 ` Sergej Proskurin
2016-08-11 9:21 ` Julien Grall
2016-08-01 17:10 ` [PATCH v2 22/25] arm/altp2m: Adjust debug information to altp2m Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 23/25] arm/altp2m: Extend libxl to activate altp2m on ARM Sergej Proskurin
2016-08-02 11:59 ` Wei Liu
2016-08-02 14:07 ` Sergej Proskurin
2016-08-11 16:00 ` Wei Liu
2016-08-15 16:07 ` Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 24/25] arm/altp2m: Extend xen-access for " Sergej Proskurin
2016-08-01 17:10 ` [PATCH v2 25/25] arm/altp2m: Add test of xc_altp2m_change_gfn Sergej Proskurin
2016-08-02 9:14 ` Razvan Cojocaru
2016-08-02 9:50 ` Sergej Proskurin
2016-08-01 18:15 ` [PATCH v2 00/25] arm/altp2m: Introducing altp2m to ARM Julien Grall
2016-08-01 19:20 ` Tamas K Lengyel
2016-08-01 19:55 ` Julien Grall
2016-08-01 20:35 ` Sergej Proskurin
2016-08-01 20:41 ` Tamas K Lengyel
2016-08-02 7:38 ` Julien Grall
2016-08-02 11:17 ` George Dunlap
2016-08-02 15:48 ` Tamas K Lengyel
2016-08-02 16:05 ` George Dunlap
2016-08-02 16:09 ` Tamas K Lengyel
2016-08-02 16:40 ` Julien Grall
2016-08-02 17:01 ` Tamas K Lengyel
2016-08-02 17:22 ` Tamas K Lengyel
2016-08-02 16:00 ` Tamas K Lengyel
2016-08-02 16:11 ` Julien Grall
2016-08-02 16:22 ` Tamas K Lengyel
2016-08-01 23:14 ` Andrew Cooper
2016-08-02 7:34 ` Julien Grall
2016-08-02 16:08 ` Andrew Cooper
2016-08-02 16:30 ` Tamas K Lengyel
2016-08-03 11:53 ` Julien Grall
2016-08-03 12:00 ` Andrew Cooper
2016-08-03 12:13 ` Julien Grall
2016-08-03 12:18 ` Andrew Cooper
2016-08-03 12:45 ` Sergej Proskurin
2016-08-03 14:08 ` Julien Grall
2016-08-03 14:17 ` Sergej Proskurin
2016-08-03 16:01 ` Tamas K Lengyel
2016-08-03 16:24 ` Julien Grall
2016-08-03 16:42 ` Tamas K Lengyel
2016-08-03 16:51 ` Julien Grall
2016-08-03 17:30 ` Andrew Cooper
2016-08-03 17:43 ` Tamas K Lengyel
2016-08-03 17:45 ` Julien Grall
2016-08-03 17:51 ` Tamas K Lengyel
2016-08-03 17:56 ` Julien Grall
2016-08-03 18:11 ` Tamas K Lengyel
2016-08-03 18:16 ` Julien Grall
2016-08-03 18:21 ` Tamas K Lengyel
2016-08-04 11:13 ` George Dunlap
2016-08-08 4:44 ` Tamas K Lengyel
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