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From: Ian Jackson <iwj@xenproject.org>
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>, "Roger Pau Monné" <roger.pau@citrix.com>,
	"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 17:17:09 +0000	[thread overview]
Message-ID: <24627.59157.450971.787744@mariner.uk.xensource.com> (raw)
In-Reply-To: <04a2869a-282f-783a-6c03-8a2d7209411a@suse.com>

Jan Beulich writes ("Re: [PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page"):
> On 22.02.2021 12:25, Ian Jackson wrote:
> > Jan Beulich writes ("[PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page"):
> >> 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.
> > 
> > Thanks.
> > 
> >>   This comes at
> >> the price of not being able to handle an error other than by crashing
> >> the domain.
> > 
> > How worried should I be about this ?
> 
> Not overly much I would say. The difference is between a failure
> (-ENOMEM) during domain creation vs the domain getting crashed
> before it gets first scheduled. This is certainly less friendly
> to the user, but lack of memory shouldn't typically happen when
> creating domains. Plus the memory talked about here is such that
> gets provided explicitly to the domain (the p2m pool), rather
> than a system wide pool.

OK, thanks.

Release-Acked-by: Ian Jackson <iwj@xenproject.org>


  reply	other threads:[~2021-02-22 17:17 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 [this message]
2021-02-22 12:15   ` Roger Pau Monné
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

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