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From: Jason Wang <jasowang@redhat.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>
Cc: yuanhan.liu@linux.intel.com, qemu-devel@nongnu.org,
	peterx@redhat.com, marcandre.lureau@gmail.com, wexu@redhat.com,
	vkaplans@redhat.com, jfreiman@redhat.com
Subject: Re: [Qemu-devel] [PATCH 6/6] spec/vhost-user spec: Add IOMMU support
Date: Fri, 19 May 2017 15:46:36 +0800	[thread overview]
Message-ID: <aea73610-1b28-3ac9-4787-36b0f70c07f1@redhat.com> (raw)
In-Reply-To: <63eaa3cf-1114-0ab2-da05-9f2731464c83@redhat.com>



On 2017年05月18日 16:43, Maxime Coquelin wrote:
>>>
>>> +When the VHOST_USER_PROTOCOL_F_SLAVE_REQ is supported by the slave, 
>>> and the
>>> +master initiated the slave to master communication channel using the
>>> +VHOST_USER_SET_SLAVE_REQ_FD request, the slave can send IOTLB miss 
>>> and access
>>> +failure events by sending VHOST_USER_SLAVE_IOTLB_MSG requests to 
>>> the master
>>> +with a struct vhost_iotlb_msg payload. For miss events, the iotlb 
>>> payload has
>>> +to be filled with the miss message type (1), the I/O virtual 
>>> address and the
>>> +permissions flags. For access failure event, the iotlb payload has 
>>> to be
>>> +filled with the access failure message type (4), the I/O virtual 
>>> address and
>>> +the permissions flags.
>>
>> I don't think slave should cache invalid entries. If it does not,
>> how can it detect access failure as opposed to a miss?
>
> Of course, invalid cache entries should not be cached.
> The VHOST_IOTLB_ACCESS_FAIL has been specified for the Kernel backend,
> even if the latter does not implement it yet. 

Yes, I leave this for future use e.g reporting copy_to_user() failure to 
userspace.

Thanks

  reply	other threads:[~2017-05-19  7:46 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-11 12:32 [Qemu-devel] [PATCH 0/6] vhost-user: Specify and implement device IOTLB support Maxime Coquelin
2017-05-11 12:32 ` [Qemu-devel] [PATCH 1/6] vhost: propagate errors in vhost_device_iotlb_miss() Maxime Coquelin
2017-05-11 12:32 ` [Qemu-devel] [PATCH 2/6] vhost: rework IOTLB messaging Maxime Coquelin
2017-05-11 12:32 ` [Qemu-devel] [PATCH 3/6] vhost: Update rings information for IOTLB earlier Maxime Coquelin
2017-05-11 17:33   ` Michael S. Tsirkin
2017-05-12 11:21     ` Maxime Coquelin
2017-05-17 16:41       ` Michael S. Tsirkin
2017-05-18  7:35         ` Maxime Coquelin
2017-05-18 14:45           ` Maxime Coquelin
2017-05-18 15:24             ` Michael S. Tsirkin
2017-05-19  9:48               ` Maxime Coquelin
2017-05-19 20:37                 ` Michael S. Tsirkin
2017-05-11 12:32 ` [Qemu-devel] [PATCH 4/6] vhost-user: add vhost_user to hold the chr Maxime Coquelin
2017-05-11 12:32 ` [Qemu-devel] [PATCH 5/6] vhost-user: add slave-req-fd support Maxime Coquelin
2017-05-11 12:32 ` [Qemu-devel] [PATCH 6/6] spec/vhost-user spec: Add IOMMU support Maxime Coquelin
2017-05-11 18:25   ` Michael S. Tsirkin
2017-05-12 14:21     ` Maxime Coquelin
2017-05-13  0:02       ` Michael S. Tsirkin
2017-05-15  5:45         ` Jason Wang
2017-05-16 15:16           ` Michael S. Tsirkin
2017-05-17  2:53             ` Jason Wang
2017-05-17 14:10               ` Maxime Coquelin
2017-05-19  6:48                 ` Jason Wang
2017-05-19  8:35                   ` Maxime Coquelin
2017-05-17 15:27         ` Maxime Coquelin
2017-05-16  8:19       ` Maxime Coquelin
2017-05-16 13:23         ` Michael S. Tsirkin
2017-05-17 16:48   ` Michael S. Tsirkin
2017-05-18  8:43     ` Maxime Coquelin
2017-05-19  7:46       ` Jason Wang [this message]
2017-05-19 16:42         ` Michael S. Tsirkin
2017-05-11 13:25 ` [Qemu-devel] [PATCH 0/6] vhost-user: Specify and implement device IOTLB support no-reply

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