Dear Ping,
I already agreed that code needs to be fixed, but the point is that looking for
container fd is not right way to detect if vfio-pci can be used or not...
--
Damjan
> On 2 Jan 2019, at 02:49, Yu, Ping <ping...@intel.com> wrote:
>
> Hi, Damjan,
>
> The issue existing in the code is container fd is initialized as “-1”, and
> there is no code to update it before trying to read iommu_group in pci.c,
> and container_fd is the condition required. See below code.
>
>
> if (lvm->container_fd != -1)
> {
> u8 *tmpstr;
> vec_reset_length (f);
> f = format (f, "%v/iommu_group%c", dev_dir_name, 0);
> tmpstr = clib_sysfs_link_to_name ((char *) f);
> if (tmpstr)
> {
> di->iommu_group = atoi ((char *) tmpstr);
> vec_free (tmpstr);
> }
> <>
> <>From: Damjan Marion [mailto:dmar...@me.com]
> Sent: Sunday, December 30, 2018 7:10 PM
> To: Yu, Ping <ping...@intel.com>
> Cc: vpp-dev@lists.fd.io
> Subject: Re: [vpp-dev] found some issue in pci vfio
>
>
> Fact that you can open vfio container doesn't actually mean that you can use
> vfio-pci module on specific PCI device.
>
> vfio-pci module can be used in 2 cases:
> - when /sys/bus/pci/devices/<PCI ADDRESS>/iommu_group exists
> - when /sys/module/vfio/parameters/enable_unsafe_noiommu_mode is set to Y
> (introduced in kernel 4.4)
>
> That code needs to be fixed, but I don't think your fix is the right one....
>
>
>
> On 29 Dec 2018, at 04:46, Yu, Ping <ping...@intel.com
> <mailto:ping...@intel.com>> wrote:
>
> I submitted a patch to fix it.
>
> https://gerrit.fd.io/r/16640 <https://gerrit.fd.io/r/16640>
>
> Ping
>
> From: Yu, Ping
> Sent: Saturday, December 29, 2018 10:43 AM
> To: vpp-dev@lists.fd.io <mailto:vpp-dev@lists.fd.io>
> Cc: Yu, Ping <ping...@intel.com <mailto:ping...@intel.com>>
> Subject: found some issue in pci vfio
>
> Hello, all
>
> Recently I met some issue in vfio, and below is some root cause:
>
> Before running vpp, I will use “dpdk-devbind.py” to bind the NIC to vfio-pci,
> and then use “uio-driver auto” configure, and it once worked well, but it has
> problem recently, so I took a look at this to resolve the problem.
> I found that vpp has some problem to “auto” detect the uio-driver to be vfio,
> and the bug info is below:
> 1) vlib_pci_bind_to_uio is dependent vlib_pci_get_device_info to tell
> iommu_group
> 2) vlib_pci_get_device_info will check whether lvm->container_fd == -1
>
> In my case, lvm->container_fd is initialized to be “-1”, and there is no
> chance to modify it, so in the eye of vlib_pci_bind_to_uio, iommu_group is
> -1, then it will try to enable noiommu mode. If some kernel enabled NOIOMMU,
> then vfio can continue work with noiommu mode, but if not, then this device
> will be rejected due to “no VFIO” support. (pci.c # 411. )
>
> The solution is to drop “auto” mode, and explicitly configure “vfio-pci” in
> the configuration, but I hope the default “auto” mode can be smarter.
>
> Ping
>
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> --
> Damjan
--
Damjan
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