-----Original Message-----

Date: Thu, 26 Jul 2018 11:35:43 +0200
From: Thomas Monjalon <redacted>
To: Takeshi Yoshimura <redacted>
Cc: dev@dpdk.org, Anatoly Burakov <redacted>
Subject: Re: [dpdk-dev] [PATCH v5] vfio: fix workaround of BAR mapping


20/07/2018 10:13, Takeshi Yoshimura:

quoted

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 <redacted>
Reviewed-by: Anatoly Burakov <redacted>

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?

Applied, thanks