linux-kernel - Re: [Xen-devel] [PATCHv2 10/10] xen/balloon: pre-allocate p2m entries for ballooned pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <55B60F6E.3040901@citrix.com>
Date:	Mon, 27 Jul 2015 12:01:02 +0100
From:	Julien Grall <julien.grall@...rix.com>
To:	David Vrabel <david.vrabel@...rix.com>,
	<xen-devel@...ts.xenproject.org>
CC:	<linux-mm@...ck.org>, Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	"Daniel Kiper" <daniel.kiper@...cle.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCHv2 10/10] xen/balloon: pre-allocate p2m entries
 for ballooned pages

On 27/07/15 10:30, David Vrabel wrote:
> On 25/07/15 00:21, Julien Grall wrote:
>> On 24/07/2015 12:47, David Vrabel wrote:
>>> @@ -550,6 +551,11 @@ int alloc_xenballooned_pages(int nr_pages, struct
>>> page **pages)
>>>           page = balloon_retrieve(true);
>>>           if (page) {
>>>               pages[pgno++] = page;
>>> +#ifdef CONFIG_XEN_HAVE_PVMMU
>>> +            ret = xen_alloc_p2m_entry(page_to_pfn(page));
>>
>> Don't you want to call this function only when the guest is not using
>> auto-translated physmap?
> 
> xen_alloc_p2m_entry() is a nop in auto-xlate guests, so no need for an
> additional check here.

I don't have the impression it's the case or it's not obvious.

For instance xen_p2m_addr, used within with the xen_alloc_p2m_entry (old
name alloc_p2m) is never set for auto-xlate guests. Therefore the value
is 0.

Same for p2m_identity and p2m_missing & co.

Regards,

-- 
Julien Grall
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/