xen-devel.lists.xenproject.org archive mirror
 help / color / mirror / Atom feed
From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>, Wei Liu <wl@xen.org>,
	Ian Jackson <iwj@xenproject.org>,
	George Dunlap <george.dunlap@citrix.com>,
	Kevin Tian <kevin.tian@intel.com>,
	Jun Nakajima <jun.nakajima@intel.com>,
	Julien Grall <julien@xen.org>
Subject: Re: [PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page
Date: Mon, 22 Feb 2021 13:15:01 +0100	[thread overview]
Message-ID: <YDOgRZoD46xrMlRP@Air-de-Roger> (raw)
In-Reply-To: <90271e69-c07e-a32c-5531-a79b10ef03dd@suse.com>

On Mon, Feb 22, 2021 at 11:56:58AM +0100, Jan Beulich wrote:
> Inserting the mapping at domain creation time leads to a memory leak
> when the creation fails later on and the domain uses separate CPU and
> IOMMU page tables - the latter requires intermediate page tables to be
> allocated, but there's no freeing of them at present in this case. Since
> we don't need the p2m insertion to happen this early, avoid the problem
> altogether by deferring it until the last possible point. This comes at
> the price of not being able to handle an error other than by crashing
> the domain.
> 
> Reported-by: Julien Grall <julien@xen.org>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Roger Pau Monné <roger.pau@citrix.com>

> ---
> v3: New (split out).
> ---
> Hooking p2m insertion onto arch_domain_creation_finished() isn't very
> nice, but I couldn't find any better hook (nor a good place where to
> introduce a new one). In particular there look to be no hvm_funcs hooks
> being used on a domain-wide basis (except for init/destroy of course).
> I did consider connecting this to the setting of HVM_PARAM_IDENT_PT, but
> considered this no better, the more that the tool stack could be smarter
> and avoid setting that param when not needed.

I'm not specially found of allocating the page in one hook, mapping it
into the p2m in another hook and finally setting up the vmcs fields in
yet another hook.

I would rather prefer to have a single place where for the BSP the
page is allocated and mapped into the p2m, while for APs just the vmcs
fields are set. It's IMO slightly difficult to follow the setup when
it's split into so many different places.

Thanks, Roger.


  parent reply	other threads:[~2021-02-22 12:15 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-22 10:55 [PATCH v3 0/2] VMX: apic access page handling adjustments Jan Beulich
2021-02-22 10:56 ` [PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page Jan Beulich
2021-02-22 11:25   ` Ian Jackson
2021-02-22 14:05     ` Jan Beulich
2021-02-22 17:17       ` Ian Jackson
2021-02-22 12:15   ` Roger Pau Monné [this message]
2021-02-25  8:44   ` Jan Beulich
2021-02-26  7:06     ` Tian, Kevin
2021-02-22 10:57 ` [PATCH v3 2/2] VMX: use a single, global " Jan Beulich
2021-03-01  2:34   ` Tian, Kevin
2021-03-01  8:18     ` Jan Beulich
2021-04-12 10:40 ` [PATCH v4] " Jan Beulich
2021-04-12 15:31   ` Roger Pau Monné
2021-04-13  9:24     ` Jan Beulich
2021-04-13 10:18       ` Roger Pau Monné
2021-04-13 12:03         ` Jan Beulich
2021-04-13 13:03           ` Roger Pau Monné
2021-04-17 19:24   ` Tim Deegan
2021-04-19 11:25     ` Jan Beulich
2021-04-22  7:42       ` Tim Deegan
2021-04-22  9:38         ` Jan Beulich
2021-04-22 15:05           ` Tim Deegan
2021-04-23 10:51 ` [PATCH v4 0/3] VMX APIC access page and shadow adjustments Jan Beulich
2021-04-23 10:52   ` [PATCH v4 1/3] VMX: use a single, global APIC access page Jan Beulich
2021-04-23 14:17     ` Roger Pau Monné
2021-04-23 14:42       ` Jan Beulich
2021-04-26 17:55         ` Tim Deegan
2021-04-25  1:27     ` Tian, Kevin
2021-04-26 17:53     ` Tim Deegan
2021-04-23 10:53   ` [PATCH v4 2/3] x86/shadow: re-use variables in shadow_get_page_from_l1e() Jan Beulich
2021-04-23 10:54   ` [PATCH v4 3/3] x86/shadow: streamline shadow_get_page_from_l1e() Jan Beulich
2021-04-23 11:00   ` Really v5 (was: [PATCH v4 0/3] VMX APIC access page and shadow adjustments) Jan Beulich

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YDOgRZoD46xrMlRP@Air-de-Roger \
    --to=roger.pau@citrix.com \
    --cc=andrew.cooper3@citrix.com \
    --cc=george.dunlap@citrix.com \
    --cc=iwj@xenproject.org \
    --cc=jbeulich@suse.com \
    --cc=julien@xen.org \
    --cc=jun.nakajima@intel.com \
    --cc=kevin.tian@intel.com \
    --cc=wl@xen.org \
    --cc=xen-devel@lists.xenproject.org \
    --subject='Re: [PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).