From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v4 15/17] x86/VPMU: NMI-based VPMU support
Date: Tue, 04 Feb 2014 11:50:29 -0500
Message-ID: <52F11A55.4020708@oracle.com>
References: <1390331342-3967-1-git-send-email-boris.ostrovsky@oracle.com>
	<1390331342-3967-16-git-send-email-boris.ostrovsky@oracle.com>
	<52F0E1BB0200007800118F8E@nat28.tlf.novell.com>
	<52F115E3.3050109@oracle.com>
	<52F126570200007800119259@nat28.tlf.novell.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"; Format="flowed"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
In-Reply-To: <52F126570200007800119259@nat28.tlf.novell.com>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Jan Beulich <JBeulich@suse.com>
Cc: keir@xen.org, suravee.suthikulpanit@amd.com, andrew.cooper3@citrix.com, eddie.dong@intel.com, dietmar.hahn@ts.fujitsu.com, xen-devel@lists.xen.org, jun.nakajima@intel.com
List-Id: xen-devel@lists.xenproject.org

On 02/04/2014 11:41 AM, Jan Beulich wrote:
>>>> On 04.02.14 at 17:31, Boris Ostrovsky <boris.ostrovsky@oracle.com> wrote:
>> On 02/04/2014 06:48 AM, Jan Beulich wrote:
>>> And then I'm still missing a reasonable level of analysis that the
>>> previously non-NMI-only interrupt handler is now safe to use in NMI
>>> context.
>> How about this?
> Looks okay, except ...
>
>> With send_guest_vcpu_virq() and hvm_get_segment_register() for PV(H) and
>> vlapic accesses for HVM moved to sofint, the only routines/macros that
>> vpmu_do_interrupt() calls in NMI mode are:
>> * memcpy()
>> * querying domain type (is_XX_domain())
>> * guest_cpu_user_regs()
>> * XLAT_cpu_user_regs()
>> * raise_softirq()
>> * vcpu_vpmu()
>> * vpmu_ops->arch_vpmu_save()
>> * vpmu_ops->do_interrupt() (in the future for PVH support)
>>
>> The latter two can only access PMU MSRs.
> ... that this additionally needs to exclude things like
> {rd,wr}msr_safe() (i.e. stuff raising exceptions that normally
> get recovered from).


I'll add that. And probably a comment in vendor-specific code to remind 
people that these routines need to be NMI-safe.


-boris