From: Tim Deegan <tim@xen.org>
To: Robert Phillips <robert.phillips@citrix.com>
Cc: xen-devel@lists.xen.org
Subject: Re: [PATCH] Avoid race when guest switches between log dirty mode and dirty vram mode.
Date: Thu, 13 Dec 2012 12:11:55 +0000 [thread overview]
Message-ID: <20121213121155.GC75286@ocelot.phlegethon.org> (raw)
In-Reply-To: <1355166836-11338-1-git-send-email-robert.phillips@citrix.com>
At 14:13 -0500 on 10 Dec (1355148836), Robert Phillips wrote:
> The previous code assumed the guest would be in one of three mutually exclusive
> modes for bookkeeping dirty pages: (1) shadow, (2) hap utilizing the log dirty
> bitmap to support functionality such as live migrate, (3) hap utilizing the
> log dirty bitmap to track dirty vram pages.
> Races arose when a guest attempted to track dirty vram while performing live
> migrate. (The dispatch table managed by paging_log_dirty_init() might change
> in the middle of a log dirty or a vram tracking function.)
>
> This change allows hap log dirty and hap vram tracking to be concurrent.
> Vram tracking no longer uses the log dirty bitmap. Instead it detects
> dirty vram pages by examining their p2m type. The log dirty bitmap is only
> used by the log dirty code. Because the two operations use different
> mechanisms, they are no longer mutually exclusive.
>
> Signed-Off-By: Robert Phillips <robert.phillips@citrix.com>
Applied; thanks for that.
Tim.
prev parent reply other threads:[~2012-12-13 12:11 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-10 19:13 [PATCH] Avoid race when guest switches between log dirty mode and dirty vram mode Robert Phillips
2012-12-13 12:11 ` Tim Deegan [this message]
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