[dpdk-dev] [PATCH v5] vfio: fix workaround of BAR mapping

[Burakov, Anatoly]

On 29-Jul-18 9:44 AM, Jerin Jacob wrote:
> -----Original Message-----
>> Date: Thu, 26 Jul 2018 11:35:43 +0200
>> From: Thomas Monjalon <thomas at monjalon.net>
>> To: Takeshi Yoshimura <t.yoshimura8869 at gmail.com>
>> Cc: dev at dpdk.org, Anatoly Burakov <anatoly.burakov at intel.com>
>> Subject: Re: [dpdk-dev] [PATCH v5] vfio: fix workaround of BAR mapping
>>
>>
>> 20/07/2018 10:13, Takeshi Yoshimura:
>>> Currently, VFIO will try to map around MSI-X table in the BARs. When
>>> MSI-X table (page-aligned) size is equal to (page-aligned) size of BAR,
>>> VFIO will just skip the BAR.
>>>
>>> Recent kernel versions will allow VFIO to map the entire BAR containing
>>> MSI-X tables (*), so instead of trying to map around the MSI-X vector
>>> or skipping the BAR entirely if it's not possible, we can now try
>>> mapping the entire BAR first. If mapping the entire BAR doesn't
>>> succeed, fall back to the old behavior of mapping around MSI-X table or
>>> skipping the BAR.
>>>
>>> (*): "vfio-pci: Allow mapping MSIX BAR",
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
>>> commit/?id=a32295c612c57990d17fb0f41e7134394b2f35f6
>>>
>>> Fixes: 90a1633b2347 ("eal/linux: allow to map BARs with MSI-X tables")
>>>
>>> Signed-off-by: Takeshi Yoshimura <t.yoshimura8869 at gmail.com>
>>> Reviewed-by: Anatoly Burakov <anatoly.burakov at intel.com>
> 
> 
> This change set breaks thunderx/octeontx platform with following error.(Tested with 4.9.0 kernel)
> 
> EAL:   probe driver: 177d:a034 net_thunderx
> EAL:   using IOMMU type 1 (Type 1)
> EAL: pci_map_resource(): cannot mmap(44, 0xffff60200000, 0x200000, 0x40000000000): Invalid argument (0xffffffffffffffff)
> EAL: PCI device 0001:01:00.2 on NUMA socket 0
> EAL:   probe driver: 177d:a034 net_thunderx
> EAL: pci_map_resource(): cannot mmap(47, 0xffff60600000, 0x200000, 0x40000000000): Invalid argument (0xffffffffffffffff)
> 
> According Linux kernel change, user space application suppose to use VFIO_REGION_INFO_CAP_MSIX_MAPPABLE
> capability to detect this feature to work < 4.15 kernel. Right? if so, Why we
> are doing this retry based logic?

I don't think anything's broken there - just a gratuitous error message.

But yes, i seem to have missed the region info flag. It was my 
suggestion to use the retry logic. I'll submit a patch fixing this.

> 
> 
> 
> 
> 
>>
>> Applied, thanks
>>
>>
>>
> 


-- 
Thanks,
Anatoly