From: "Jürgen Groß" <jgross@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Xen-devel <xen-devel@lists.xenproject.org>
Cc: Ross Lagerwall <ross.lagerwall@citrix.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [Xen-devel] [PATCH v1.5] x86/livepatch: Prevent patching with active waitqueues
Date: Fri, 22 Nov 2019 11:13:29 +0100 [thread overview]
Message-ID: <492ecee9-9e1c-52c2-e89d-ec02f95bf3c9@suse.com> (raw)
In-Reply-To: <20191105194909.32234-1-andrew.cooper3@citrix.com>
On 05.11.19 20:49, Andrew Cooper wrote:
> The safety of livepatching depends on every stack having been unwound, but
> there is one corner case where this is not true. The Sharing/Paging/Monitor
> infrastructure may use waitqueues, which copy the stack frame sideways and
> longjmp() to a different vcpu.
>
> This case is rare, and can be worked around by pausing the offending
> domain(s), waiting for their rings to drain, then performing a livepatch.
>
> In the case that there is an active waitqueue, fail the livepatch attempt with
> -EBUSY, which is preforable to the fireworks which occur from trying to unwind
> the old stack frame at a later point.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Juergen
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next prev parent reply other threads:[~2019-11-22 10:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 19:43 [Xen-devel] [PATCH for-4.13 0/2] xen/livepatch: Safety fixes Andrew Cooper
2019-11-05 19:43 ` [Xen-devel] [PATCH 1/2] xen/livepatch: Add a return value to load hooks Andrew Cooper
2019-11-06 14:20 ` Konrad Rzeszutek Wilk
2019-11-06 14:35 ` Jan Beulich
2019-11-08 10:21 ` Ross Lagerwall
2019-11-05 19:43 ` [Xen-devel] [PATCH 2/2] x86/livepatch: Prevent patching with active waitqueues Andrew Cooper
2019-11-05 19:49 ` [Xen-devel] [PATCH v1.5] " Andrew Cooper
2019-11-22 10:13 ` Jürgen Groß [this message]
2019-11-23 3:23 ` Sarah Newman
2019-11-23 4:48 ` Sarah Newman
2019-11-06 14:25 ` [Xen-devel] [PATCH 2/2] " Konrad Rzeszutek Wilk
2019-11-08 10:18 ` Ross Lagerwall
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