From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <JBeulich@suse.com>
Subject: Re: [PATCH v7 12/19] x86/VPMU: Initialize PMU for PV
	guests
Date: Wed, 11 Jun 2014 13:53:27 +0100
Message-ID: <53986D670200007800019EDF@mail.emea.novell.com>
References: <1402076415-26475-1-git-send-email-boris.ostrovsky@oracle.com>
	<1402076415-26475-13-git-send-email-boris.ostrovsky@oracle.com>
	<539849960200007800019D87@mail.emea.novell.com>
	<53985074.4010205@oracle.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
In-Reply-To: <53985074.4010205@oracle.com>
Content-Disposition: inline
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: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: kevin.tian@intel.com, keir@xen.org, suravee.suthikulpanit@amd.com, tim@xen.org, dietmar.hahn@ts.fujitsu.com, xen-devel@lists.xen.org, jun.nakajima@intel.com
List-Id: xen-devel@lists.xenproject.org

>>> On 11.06.14 at 14:49, <boris.ostrovsky@oracle.com> wrote:
> On 06/11/2014 06:20 AM, Jan Beulich wrote:
>>>>> On 06.06.14 at 19:40, <boris.ostrovsky@oracle.com> wrote:
>>> Code for initializing/tearing down PMU for PV guests
>>> ...
>>> --- a/xen/arch/x86/hvm/hvm.c
>>> +++ b/xen/arch/x86/hvm/hvm.c
>>> @@ -4031,7 +4031,8 @@ static hvm_hypercall_t *const 
> pvh_hypercall64_table[NR_hypercalls] = {
>>>       [ __HYPERVISOR_physdev_op ]      = (hvm_hypercall_t *)hvm_physdev_op,
>>>       HYPERCALL(hvm_op),
>>>       HYPERCALL(sysctl),
>>> -    HYPERCALL(domctl)
>>> +    HYPERCALL(domctl),
>>> +    HYPERCALL(xenpmu_op)
>> How is this change related to the subject and description?
> 
> Yes, this is result of my eliminating PVH patch as a standalone one and 
> spreading its content over other patches. I'll update the text.
> 
>>
>>> +static int pvpmu_init(struct domain *d, xen_pmu_params_t *params)
>>> +{
>>> +    struct vcpu *v;
>>> +    struct page_info *page;
>>> +    uint64_t gfn = params->d.val;
>>> +
>>> +    if ( !params || params->vcpu >= d->max_vcpus )
>>> +        return -EINVAL;
>>> +
>>> +    page = get_page_from_gfn(d, gfn, NULL, P2M_ALLOC);
>>> +    if ( !page )
>>> +        return -EINVAL;
>>> +
>>> +    if ( !get_page_type(page, PGT_writable_page) )
>>> +    {
>>> +        put_page(page);
>>> +        return -EINVAL;
>>> +    }
>>> +
>>> +    v = d->vcpu[params->vcpu];
>> I'm sure I asked this before - what guarantees (now as well as
>> going forward) that you get non-NULL here? Various existing
>> code paths properly verify both d->vcpu and d->vcpu[...] not
>> being NULL, so you should do this consistently too.
> 
> Ah, I thought you were referring to params check last time. I'll add 
> vcpu checks as well.

And drop checking param against NULL - I don't think that check
makes any sense.

Jan