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From: "Mika Penttilä" <mika.penttila@nextfour.com>
To: Alex Williamson <alex.williamson@redhat.com>,
	Yan Zhao <yan.y.zhao@intel.com>
Cc: "zhenyuw@linux.intel.com" <zhenyuw@linux.intel.com>,
	"intel-gvt-dev@lists.freedesktop.org" 
	<intel-gvt-dev@lists.freedesktop.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>,
	"kevin.tian@intel.com" <kevin.tian@intel.com>,
	"peterx@redhat.com" <peterx@redhat.com>
Subject: Re: [PATCH v2 1/2] vfio: introduce vfio_dma_rw to read/write a range of IOVAs
Date: Thu, 16 Jan 2020 02:30:52 +0000
Message-ID: <80cf3888-2e51-3fd7-a064-213e7ded188e@nextfour.com> (raw)
In-Reply-To: <20200115130638.6926dd08@w520.home>



On 15.1.2020 22.06, Alex Williamson wrote:
> On Tue, 14 Jan 2020 22:53:03 -0500
> Yan Zhao <yan.y.zhao@intel.com> wrote:
>
>> vfio_dma_rw will read/write a range of user space memory pointed to by
>> IOVA into/from a kernel buffer without pinning the user space memory.
>>
>> TODO: mark the IOVAs to user space memory dirty if they are written in
>> vfio_dma_rw().
>>
>> Cc: Kevin Tian <kevin.tian@intel.com>
>> Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
>> ---
>>   drivers/vfio/vfio.c             | 45 +++++++++++++++++++
>>   drivers/vfio/vfio_iommu_type1.c | 76 +++++++++++++++++++++++++++++++++
>>   include/linux/vfio.h            |  5 +++
>>   3 files changed, 126 insertions(+)
>>
>> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
>> index c8482624ca34..8bd52bc841cf 100644
>> --- a/drivers/vfio/vfio.c
>> +++ b/drivers/vfio/vfio.c
>> @@ -1961,6 +1961,51 @@ int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn, int npage)
>>   }
>>   EXPORT_SYMBOL(vfio_unpin_pages);
>>   
>> +/*
>> + * Read/Write a range of IOVAs pointing to user space memory into/from a kernel
>> + * buffer without pinning the user space memory
>> + * @dev [in]  : device
>> + * @iova [in] : base IOVA of a user space buffer
>> + * @data [in] : pointer to kernel buffer
>> + * @len [in]  : kernel buffer length
>> + * @write     : indicate read or write
>> + * Return error code on failure or 0 on success.
>> + */
>> +int vfio_dma_rw(struct device *dev, dma_addr_t iova, void *data,
>> +		   size_t len, bool write)
>> +{
>> +	struct vfio_container *container;
>> +	struct vfio_group *group;
>> +	struct vfio_iommu_driver *driver;
>> +	int ret = 0;

Do you know the iova given to vfio_dma_rw() is indeed a gpa and not iova 
from a iommu mapping? So isn't it you actually assume all the guest is 
pinned,
like from device assignment?

Or who and how is the vfio mapping added before the vfio_dma_rw() ?

Thanks,
Mika


  reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15  3:41 [PATCH v2 0/2] use vfio_dma_rw to read/write IOVAs from CPU side Yan Zhao
2020-01-15  3:53 ` [PATCH v2 1/2] vfio: introduce vfio_dma_rw to read/write a range of IOVAs Yan Zhao
2020-01-15 20:06   ` Alex Williamson
2020-01-16  2:30     ` Mika Penttilä [this message]
2020-01-16  2:59       ` Alex Williamson
2020-01-16  3:15         ` Mika Penttilä
2020-01-16  3:58           ` Alex Williamson
2020-01-16  5:32     ` Yan Zhao
2020-01-15  3:54 ` [PATCH v2 2/2] drm/i915/gvt: subsitute kvm_read/write_guest with vfio_dma_rw Yan Zhao
2020-01-15 20:06   ` Alex Williamson
2020-01-16  5:49     ` Yan Zhao
2020-01-16 15:37       ` Alex Williamson
2020-01-19 10:06         ` Yan Zhao
2020-01-20 20:01           ` Alex Williamson
2020-01-21  8:12             ` Yan Zhao
2020-01-21 16:51               ` Alex Williamson
2020-01-21 22:10                 ` Yan Zhao
2020-01-22  3:07                   ` Yan Zhao
2020-01-23 10:02                     ` Yan Zhao

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