linux-kernel - Re: [PATCH] xen: don't use privcmd_call() from xen_mc

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Message-ID: <a4f76a2a-128f-3e2a-44ee-04d57ab5be12@oracle.com>
Date:   Tue, 7 Aug 2018 10:02:43 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Subject: Re: [PATCH] xen: don't use privcmd_call() from xen_mc_flush()

On 08/07/2018 09:11 AM, Juergen Gross wrote:
> On 13/06/18 11:58, Juergen Gross wrote:
>> Using privcmd_call() for a singleton multicall seems to be wrong, as
>> privcmd_call() is using stac()/clac() to enable hypervisor access to
>> Linux user space.
>>
>> Add a new xen_single_call() function to be use for that purpose.
>>
>> Reported-by: Jan Beulich <jbeulich@...e.com>
>> Signed-off-by: Juergen Gross <jgross@...e.com>
> Boris, any objections?


I think Jan wanted a change in commit message. I can commit with this:

"Using privcmd_call() for a singleton multicall seems to be wrong, as
 privcmd_call() is using stac()/clac() to enable hypervisor access to
 Linux user space.

 Even if currently not a problem (pv domains can't use SMAP while HVM
 and PVH domains can't use multicalls) things might change when
 PVH dom0 support is added to the kernel."


-boris