From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Tim Deegan <tim@xen.org>, Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH v3] x86/traps: Correct pagefault handling issues introduced in c/s d5c251c
Date: Thu, 15 Dec 2016 01:25:22 -0700 [thread overview]
Message-ID: <58526182020000780012983B@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1481734422-13641-1-git-send-email-andrew.cooper3@citrix.com>
>>> On 14.12.16 at 17:53, <andrew.cooper3@citrix.com> wrote:
> There are two bugs.
>
> Firstly, the ASSERT(paging_mode_only_log_dirty(d)) can trip when servicing a
> hypervisor #PF in the context of an HVM guest, e.g. a copy_to_user() failure
> in the shadow pagetable code.
>
> Secondly, the entry conditions paging_fault() were previously guarded on
> !paging_mode_external(d) which limited entry to PV contexts, but for both
> guest and hypervisor faults. Switching this to paging_mode_log_dirty()
> opened
> it up to HVM contexts as well.
>
> Reinstate the old !paging_mode_external(d) check, as it is actually the
> relevent fact, and extend the comment to explicitly state that hypervisor
> faults should follow this path.
>
> Inside, we are now guarenteed to be in the context of a PV guest, so can
> safely use the assertion about log dirty.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
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prev parent reply other threads:[~2016-12-15 8:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-14 16:53 [PATCH v3] x86/traps: Correct pagefault handling issues introduced in c/s d5c251c Andrew Cooper
2016-12-14 16:55 ` Tim Deegan
2016-12-15 8:25 ` Jan Beulich [this message]
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