Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] vhost: introduce mdev based hardware backend
To:     Tiwei Bie <tiwei.bie@intel.com>
Cc:     mst@redhat.com, alex.williamson@redhat.com,
        maxime.coquelin@redhat.com, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
        netdev@vger.kernel.org, dan.daly@intel.com,
        cunming.liang@intel.com, zhihong.wang@intel.com,
        lingshan.zhu@intel.com
References: <20190926045427.4973-1-tiwei.bie@intel.com>
 <1b4b8891-8c14-1c85-1d6a-2eed1c90bcde@redhat.com>
 <20190927045438.GA17152@___>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <49bb0777-3761-3737-8e5b-568957f9a935@redhat.com>
Date:   Fri, 27 Sep 2019 15:14:42 +0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.8.0
MIME-Version: 1.0
In-Reply-To: <20190927045438.GA17152@___>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


On 2019/9/27 下午12:54, Tiwei Bie wrote:
>>> +
>>> +		/*
>>> +		 * In vhost-mdev, userspace should pass ring addresses
>>> +		 * in guest physical addresses when IOMMU is disabled or
>>> +		 * IOVAs when IOMMU is enabled.
>>> +		 */
>> A question here, consider we're using noiommu mode. If guest physical
>> address is passed here, how can a device use that?
>>
>> I believe you meant "host physical address" here? And it also have the
>> implication that the HPA should be continuous (e.g using hugetlbfs).
> The comment is talking about the virtual IOMMU (i.e. iotlb in vhost).
> It should be rephrased to cover the noiommu case as well. Thanks for
> spotting this.


So the question still, if GPA is passed how can it be used by the 
virtio-mdev device?

Thanks