From: Wei Liu <wei.liu2@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
Wei Liu <wei.liu2@citrix.com>, Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH RFC 2/2] xen: make available hvm_fep to non-debug build as well
Date: Thu, 16 Jun 2016 13:20:55 +0100 [thread overview]
Message-ID: <20160616122055.GR28116@citrix.com> (raw)
In-Reply-To: <f7719257-0808-5189-49b4-220477d373cc@citrix.com>
On Thu, Jun 16, 2016 at 01:12:34PM +0100, Andrew Cooper wrote:
> On 16/06/16 12:52, Wei Liu wrote:
> >
> >>> + printk("**********************************************\n");
> >>> + printk("******* WARNING: HVM FORCED EMULATION PREFIX IS PERMITTED\n");
>
> I would say "available" rather than permitted in this case.
>
> >>> + printk("******* This option is *ONLY* intended to aid debugging "
> >>> + "and testing of Xen\n");
>
> Despite the line length, I would keep this string on a single line. If
> you want it a little shorter, you can drop "debugging and", leaving just
> testing.
>
> >>> + printk("******* that HVM guest can enter instruction emulator "
> >>> + "with UD instruction.\n");
>
> I think this like isn't necessary. Anyone who is unclear what FEP is
> can look it up.
>
> >>> + printk("******* It has implication on the security of the system.\n");
>
> implications.
>
All fixed.
> >>> + printk("******* Please *DO NOT* use this in production.\n");
> >>> + printk("**********************************************\n");
> >>> + add_taint(TAINT_HVM_FEP);
> >> Should we perhaps taint the system only the first time a guest
> >> makes use of this?
> >>
> > Doesn't that add overhead to a potential hot path? Arguably it is only
> > setting a bit in a flag, but still...
>
> FEP is not a fastpath at all. It would be fine to defer to
> hvm_ud_intercept().
>
NP.
Wei.
> ~Andrew
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next prev parent reply other threads:[~2016-06-16 12:20 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-15 14:31 [PATCH RFC 0/2] Make hvm_fep available to non-debug builds Wei Liu
2016-06-15 14:31 ` [PATCH RFC 1/2] xen/kernel: document 'C' in print_tainted Wei Liu
2016-06-15 14:53 ` Jan Beulich
2016-06-15 14:31 ` [PATCH RFC 2/2] xen: make available hvm_fep to non-debug build as well Wei Liu
2016-06-15 14:39 ` Doug Goldstein
2016-06-15 14:47 ` Wei Liu
2016-06-15 16:12 ` Doug Goldstein
2016-06-15 16:14 ` Wei Liu
2016-06-16 11:37 ` Jan Beulich
2016-06-16 11:52 ` Wei Liu
2016-06-16 12:12 ` Andrew Cooper
2016-06-16 12:20 ` Wei Liu [this message]
2016-06-16 12:31 ` Jan Beulich
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