It has been observed that on some platforms/devices, there may
not be enough MSI vectors for virtqueues and the config change.
Under such circumstances, the interrupt sources of a device
have to share vectors/IRQs.

This series implemented a shared IRQ feature for ifcvf.

Please help review.

For the test report, plase kindly refer to V3  cover letter:
https://www.spinics.net/lists/netdev/msg795808.html

Changes from V4:
(1) Insted of checking errors by themself, set_vq_vector() and
set_config_vector() would return the value read from the corresponding
registers, then let the caller do error handling.
So hw_disable() can use them.(Jason)
(2)Use virtio pci modern IO helers than ifcvf_read/write_xxx (Jason)
(3)Free all IRQs and vectors once failed in request_irq and its
subroutines, don't wait for a restart caused by start_datapath fail or
device reset issued from the guest.
(4) Better naming: vqs-reused-irq --> vqs_reused_irq,
ifcvf_dev_shared_irq --> ifcvf_dev_irq (Michael)
(5) A separate patch for ifcvf_hw cacheline alignment(Michael)

Changes from V3:
fix code indenting issues reported by LKP:

Changes from V2:
(1) Fix misuse of nvectors(in ifcvf_alloc_vectors return value)(Michael)
(2) Fix misuse of irq = get_vq_irq() in setup irqbypass(Michael)
(3) Coding style improvements(Michael)
(4) Better naming of device shared irq/shared vq irq

Changes from V1:
(1) Enable config interrupt when only one vector is allocated(Michael)
(2) Clean vectors/IRQs if failed to request config interrupt
since config interrupt is a must(Michael)
(3) Keep local vdpa_ops, disable irq_bypass by setting IRQ = -EINVAL
for shared IRQ case(Michael)
(4) Improvements on error messages(Michael)
(5) Squash functions implementation patches to the callers(Michael)

Zhu Lingshan (5):
  vDPA/ifcvf: make use of virtio pci modern IO helpers in ifcvf
  vhost_vdpa: don't setup irq offloading when irq_num < 0
  vDPA/ifcvf: implement device MSIX vector allocator
  vDPA/ifcvf: implement shared IRQ feature
  vDPA/ifcvf: cacheline alignment for ifcvf_hw

 drivers/vdpa/ifcvf/ifcvf_base.c | 120 +++++-------
 drivers/vdpa/ifcvf/ifcvf_base.h |  24 ++-
 drivers/vdpa/ifcvf/ifcvf_main.c | 317 ++++++++++++++++++++++++++++----
 drivers/vhost/vdpa.c            |   5 +-
 4 files changed, 349 insertions(+), 117 deletions(-)

-- 
2.27.0