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From: Wei Liu <wei.liu2@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Wei Liu <wei.liu2@citrix.com>,
	Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH RFC 2/2] xen: make available hvm_fep to non-debug build as well
Date: Thu, 16 Jun 2016 12:52:09 +0100	[thread overview]
Message-ID: <20160616115209.GP28116@citrix.com> (raw)
In-Reply-To: <5762AB7F02000078000F5A8E@prv-mh.provo.novell.com>

On Thu, Jun 16, 2016 at 05:37:03AM -0600, Jan Beulich wrote:
> >>> On 15.06.16 at 16:31, <wei.liu2@citrix.com> wrote:
> > @@ -182,6 +181,32 @@ static int __init hvm_enable(void)
> >      if ( !opt_altp2m_enabled )
> >          hvm_funcs.altp2m_supported = 0;
> >  
> > +    if ( opt_hvm_fep )
> > +    {
> > +        unsigned i, j;
> 
> unsigned int
> 

Ack.

> > +        printk("**********************************************\n");
> > +        printk("******* WARNING: HVM FORCED EMULATION PREFIX IS PERMITTED\n");
> > +        printk("******* This option is *ONLY* intended to aid debugging "
> > +               "and testing of Xen\n");
> > +        printk("******* that HVM guest can enter instruction emulator "
> > +               "with UD instruction.\n");
> > +        printk("******* It has implication on the security of the system.\n");
> > +        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...

> > +        for ( i = 0; i < 3; i++ )
> > +        {
> > +            printk("%d... ", 3-i);
> 
> %u and spaces around - please.
> 

Ack.

Wei.

> Jan
> 

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  reply	other threads:[~2016-06-16 11:52 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 [this message]
2016-06-16 12:12       ` Andrew Cooper
2016-06-16 12:20         ` Wei Liu
2016-06-16 12:31       ` Jan Beulich

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