From: Sergej Proskurin <proskurin@sec.in.tum.de>
To: Julien Grall <julien.grall@arm.com>, xen-devel@lists.xenproject.org
Cc: Stefano Stabellini <sstabellini@kernel.org>
Subject: Re: [PATCH 06/18] arm/altp2m: Add a(p2m) table flushing routines.
Date: Tue, 5 Jul 2016 10:52:49 +0200 [thread overview]
Message-ID: <02e6e5a0-f439-362f-c88f-16b3679c80ee@sec.in.tum.de> (raw)
In-Reply-To: <577A83EE.7030907@arm.com>
Hi Julien,
On 07/04/2016 05:42 PM, Julien Grall wrote:
> Hello Sergej,
>
> On 04/07/16 13:12, Sergej Proskurin wrote:
>>> +/* Reset this p2m table to be empty */
>>> +static void p2m_flush_table(struct p2m_domain *p2m)
>>> +{
>>> + struct page_info *top, *pg;
>>> + mfn_t mfn;
>>> + unsigned int i;
>>> +
>>> + /* Check whether the p2m table has already been flushed before. */
>>> + if ( p2m->root == NULL)
>>> + return;
>>> +
>>> + spin_lock(&p2m->lock);
>>> +
>>> + /*
>>> + * "Host" p2m tables can have shared entries &c that need a bit
>>> more care
>>> + * when discarding them
>>> + */
>>> + ASSERT(!p2m_is_hostp2m(p2m));
>>> +
>>> + /* Zap the top level of the trie */
>>> + top = p2m->root;
>>> +
>>> + /* Clear all concatenated first level pages */
>>> + for ( i = 0; i < P2M_ROOT_PAGES; i++ )
>>> + {
>>> + mfn = _mfn(page_to_mfn(top + i));
>>> + clear_domain_page(mfn);
>>> + }
>>> +
>>> + /* Free the rest of the trie pages back to the paging pool */
>>> + while ( (pg = page_list_remove_head(&p2m->pages)) )
>>> + if ( pg != top )
>>> + {
>>> + /*
>>> + * Before freeing the individual pages, we clear them
>>> to prevent
>>> + * reusing old table entries in future p2m allocations.
>>> + */
>>> + mfn = _mfn(page_to_mfn(pg));
>>> + clear_domain_page(mfn);
>>> + free_domheap_page(pg);
>>> + }
>>
>> At this point, we prevent only the first root level page from being
>> freed. In case there are multiple consecutive first level pages, one of
>> them will be freed in the upper loop (and potentially crash the guest if
>> the table is reused at a later point in time). However, testing for
>> every concatenated page in the if clause of the while loop would further
>> decrease the flushing performance. Thus, my question is, whether there
>> is a good way to solve this issue?
>
> The root pages are not part of p2m->pages, so there is no issue.
Thanks for clearing that up. We have already discussed this in patch #04.
>
> Regards,
>
Thank you.
Best regards,
Sergej
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next prev parent reply other threads:[~2016-07-05 8:52 UTC|newest]
Thread overview: 126+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-04 11:45 [PATCH 00/18] arm/altp2m: Introducing altp2m to ARM Sergej Proskurin
2016-07-04 11:45 ` [PATCH 01/18] arm/altp2m: Add cmd-line support for altp2m on ARM Sergej Proskurin
2016-07-04 12:15 ` Andrew Cooper
2016-07-04 13:02 ` Sergej Proskurin
2016-07-04 13:25 ` Julien Grall
2016-07-04 13:43 ` Sergej Proskurin
2016-07-04 17:42 ` Julien Grall
2016-07-04 17:56 ` Tamas K Lengyel
2016-07-04 21:08 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 02/18] arm/altp2m: Add first altp2m HVMOP stubs Sergej Proskurin
2016-07-04 13:36 ` Julien Grall
2016-07-04 13:51 ` Sergej Proskurin
2016-07-05 10:19 ` Julien Grall
2016-07-06 9:14 ` Sergej Proskurin
2016-07-06 13:43 ` Julien Grall
2016-07-06 15:23 ` Tamas K Lengyel
2016-07-06 15:54 ` Julien Grall
2016-07-06 16:05 ` Tamas K Lengyel
2016-07-06 16:29 ` Julien Grall
2016-07-06 16:35 ` Tamas K Lengyel
2016-07-06 18:35 ` Julien Grall
2016-07-07 9:14 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 03/18] arm/altp2m: Add HVMOP_altp2m_get_domain_state Sergej Proskurin
2016-07-04 11:45 ` [PATCH 04/18] arm/altp2m: Add altp2m init/teardown routines Sergej Proskurin
2016-07-04 15:17 ` Julien Grall
2016-07-04 16:40 ` Sergej Proskurin
2016-07-04 16:43 ` Andrew Cooper
2016-07-04 16:56 ` Sergej Proskurin
2016-07-04 17:44 ` Julien Grall
2016-07-04 21:19 ` Sergej Proskurin
2016-07-04 21:35 ` Julien Grall
2016-07-04 21:46 ` Sergej Proskurin
2016-07-04 18:18 ` Julien Grall
2016-07-04 21:37 ` Sergej Proskurin
2016-07-04 18:30 ` Julien Grall
2016-07-04 21:56 ` Sergej Proskurin
2016-07-04 16:15 ` Julien Grall
2016-07-04 16:51 ` Sergej Proskurin
2016-07-04 18:34 ` Julien Grall
2016-07-05 7:45 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 05/18] arm/altp2m: Add HVMOP_altp2m_set_domain_state Sergej Proskurin
2016-07-04 15:39 ` Julien Grall
2016-07-05 8:45 ` Sergej Proskurin
2016-07-05 10:11 ` Julien Grall
2016-07-05 12:05 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 06/18] arm/altp2m: Add a(p2m) table flushing routines Sergej Proskurin
2016-07-04 12:12 ` Sergej Proskurin
2016-07-04 15:42 ` Julien Grall
2016-07-05 8:52 ` Sergej Proskurin [this message]
2016-07-04 15:55 ` Julien Grall
2016-07-05 9:51 ` Sergej Proskurin
2016-07-04 16:20 ` Julien Grall
2016-07-05 9:57 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 07/18] arm/altp2m: Add HVMOP_altp2m_create_p2m Sergej Proskurin
2016-07-04 11:45 ` [PATCH 08/18] arm/altp2m: Add HVMOP_altp2m_destroy_p2m Sergej Proskurin
2016-07-04 16:32 ` Julien Grall
2016-07-05 11:37 ` Sergej Proskurin
2016-07-05 11:48 ` Julien Grall
2016-07-05 12:18 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 09/18] arm/altp2m: Add HVMOP_altp2m_switch_p2m Sergej Proskurin
2016-07-04 11:45 ` [PATCH 10/18] arm/altp2m: Renamed and extended p2m_alloc_table Sergej Proskurin
2016-07-04 18:43 ` Julien Grall
2016-07-05 13:56 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 11/18] arm/altp2m: Make flush_tlb_domain ready for altp2m Sergej Proskurin
2016-07-04 12:30 ` Sergej Proskurin
2016-07-04 20:32 ` Julien Grall
2016-07-05 14:48 ` Sergej Proskurin
2016-07-05 15:37 ` Julien Grall
2016-07-05 20:21 ` Sergej Proskurin
2016-07-06 14:28 ` Julien Grall
2016-07-06 14:39 ` Sergej Proskurin
2016-07-07 17:24 ` Julien Grall
2016-07-04 11:45 ` [PATCH 12/18] arm/altp2m: Cosmetic fixes - function prototypes Sergej Proskurin
2016-07-15 13:45 ` Julien Grall
2016-07-16 15:18 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 13/18] arm/altp2m: Make get_page_from_gva ready for altp2m Sergej Proskurin
2016-07-04 20:34 ` Julien Grall
2016-07-05 20:31 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 14/18] arm/altp2m: Add HVMOP_altp2m_set_mem_access Sergej Proskurin
2016-07-05 12:49 ` Julien Grall
2016-07-05 21:55 ` Sergej Proskurin
2016-07-06 14:32 ` Julien Grall
2016-07-06 16:12 ` Tamas K Lengyel
2016-07-06 16:59 ` Julien Grall
2016-07-06 17:03 ` Sergej Proskurin
2016-07-06 17:08 ` Julien Grall
2016-07-07 9:16 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 15/18] arm/altp2m: Add altp2m paging mechanism Sergej Proskurin
2016-07-04 20:53 ` Julien Grall
2016-07-06 8:33 ` Sergej Proskurin
2016-07-06 14:26 ` Julien Grall
2016-07-04 11:45 ` [PATCH 16/18] arm/altp2m: Extended libxl to activate altp2m on ARM Sergej Proskurin
2016-07-07 16:27 ` Wei Liu
2016-07-24 16:06 ` Sergej Proskurin
2016-07-25 8:32 ` Wei Liu
2016-07-25 9:04 ` Sergej Proskurin
2016-07-25 9:49 ` Julien Grall
2016-07-25 10:08 ` Wei Liu
2016-07-25 11:26 ` Sergej Proskurin
2016-07-25 11:37 ` Wei Liu
2016-07-04 11:45 ` [PATCH 17/18] arm/altp2m: Adjust debug information to altp2m Sergej Proskurin
2016-07-04 20:58 ` Julien Grall
2016-07-06 8:41 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 18/18] arm/altp2m: Extend xen-access for altp2m on ARM Sergej Proskurin
2016-07-04 13:38 ` Razvan Cojocaru
2016-07-06 8:44 ` Sergej Proskurin
2016-07-04 11:45 ` [PATCH 01/18] arm/altp2m: Add cmd-line support " Sergej Proskurin
2016-07-04 11:45 ` [PATCH 02/18] arm/altp2m: Add first altp2m HVMOP stubs Sergej Proskurin
2016-07-04 11:45 ` [PATCH 03/18] arm/altp2m: Add HVMOP_altp2m_get_domain_state Sergej Proskurin
2016-07-04 11:45 ` [PATCH 04/18] arm/altp2m: Add altp2m init/teardown routines Sergej Proskurin
2016-07-04 11:45 ` [PATCH 05/18] arm/altp2m: Add HVMOP_altp2m_set_domain_state Sergej Proskurin
2016-07-04 11:45 ` [PATCH 06/18] arm/altp2m: Add a(p2m) table flushing routines Sergej Proskurin
2016-07-04 11:45 ` [PATCH 07/18] arm/altp2m: Add HVMOP_altp2m_create_p2m Sergej Proskurin
2016-07-04 11:45 ` [PATCH 08/18] arm/altp2m: Add HVMOP_altp2m_destroy_p2m Sergej Proskurin
2016-07-04 11:45 ` [PATCH 09/18] arm/altp2m: Add HVMOP_altp2m_switch_p2m Sergej Proskurin
2016-07-04 11:45 ` [PATCH 10/18] arm/altp2m: Renamed and extended p2m_alloc_table Sergej Proskurin
2016-07-04 11:45 ` [PATCH 11/18] arm/altp2m: Make flush_tlb_domain ready for altp2m Sergej Proskurin
2016-07-04 11:45 ` [PATCH 12/18] arm/altp2m: Cosmetic fixes - function prototypes Sergej Proskurin
2016-07-04 11:46 ` [PATCH 13/18] arm/altp2m: Make get_page_from_gva ready for altp2m Sergej Proskurin
2016-07-04 11:46 ` [PATCH 14/18] arm/altp2m: Add HVMOP_altp2m_set_mem_access Sergej Proskurin
2016-07-04 11:46 ` [PATCH 15/18] arm/altp2m: Add altp2m paging mechanism Sergej Proskurin
2016-07-04 11:46 ` [PATCH 16/18] arm/altp2m: Extended libxl to activate altp2m on ARM Sergej Proskurin
2016-07-04 11:46 ` [PATCH 17/18] arm/altp2m: Adjust debug information to altp2m Sergej Proskurin
2016-07-04 11:46 ` [PATCH 18/18] arm/altp2m: Extend xen-access for altp2m on ARM Sergej Proskurin
2016-07-04 12:52 ` [PATCH 00/18] arm/altp2m: Introducing altp2m to ARM Andrew Cooper
2016-07-04 13:05 ` Sergej Proskurin
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