From: "Jürgen Groß" <jgross@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Xen-devel <xen-devel@lists.xenproject.org>
Cc: "Wei Liu" <wl@xen.org>, "Jan Beulich" <JBeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH for-4.13] x86/vvmx: Fix livelock with XSA-304 fix
Date: Sat, 23 Nov 2019 06:56:04 +0100 [thread overview]
Message-ID: <a1fb12bd-6b4a-03d2-1684-b3c965ea7ec5@suse.com> (raw)
In-Reply-To: <20191122175400.4001-1-andrew.cooper3@citrix.com>
On 22.11.19 18:54, Andrew Cooper wrote:
> It turns out that the XSA-304 / CVE-2018-12207 fix of disabling executable
> superpages doesn't work well with the nested p2m code.
>
> Nested virt is experimental and not security supported, but is useful for
> development purposes. In order to not regress the status quo, disable the
> XSA-304 workaround until the nested p2m code can be improved.
>
> Introduce a per-domain exec_sp control and set it based on the current
> opt_ept_exec_sp setting. Take the oppotunity to omit a PVH hardware domain
> from the performance hit, because it is already permitted to DoS the system in
> such ways as issuing a reboot.
>
> When nested virt is enabled on a domain, force it to using executable
> superpages and rebuild the p2m.
>
> Having the setting per-domain involves rearranging the internals of
> parse_ept_param_runtime() but it still retains the same overall semantics -
> for each applicable domain whose setting needs to change, rebuild the p2m.
>
> 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:[~2019-11-23 5:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-22 17:54 [Xen-devel] [PATCH for-4.13] x86/vvmx: Fix livelock with XSA-304 fix Andrew Cooper
2019-11-22 18:08 ` George Dunlap
2019-11-22 18:35 ` Andrew Cooper
2019-11-23 5:56 ` Jürgen Groß [this message]
2019-11-23 14:11 ` Andrew Cooper
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