tree 4a6c78521382e49267a6a17ebb7c91695b977184
parent aeb918b915a7d5cf1b08fee1f488a63f90d8cd4a
author Jeffrey Hugo <quic_jhugo@quicinc.com> 1658766823 +0000
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1659107213 +0200

PCI: hv: Fix interrupt mapping for multi-MSI

commit a2bad844a67b1c7740bda63e87453baf63c3a7f7 upstream.

According to Dexuan, the hypervisor folks beleive that multi-msi
allocations are not correct.  compose_msi_msg() will allocate multi-msi
one by one.  However, multi-msi is a block of related MSIs, with alignment
requirements.  In order for the hypervisor to allocate properly aligned
and consecutive entries in the IOMMU Interrupt Remapping Table, there
should be a single mapping request that requests all of the multi-msi
vectors in one shot.

Dexuan suggests detecting the multi-msi case and composing a single
request related to the first MSI.  Then for the other MSIs in the same
block, use the cached information.  This appears to be viable, so do it.

4.14 backport - file moved to host/pci-hyperv.c. add hv_msi_get_int_vector
helper function. Fixed merge conflict due to delivery_mode name change
(APIC_DELIVERY_MODE_FIXED is the value given to dest_Fixed). Removed unused
variable in hv_compose_msi_msg. Fixed reference to msi_desc->pci to point
to the same is_msix variable. Removed changes to compose_msi_req_v3 since
it doesn't exist yet. Added "reason" to put_pcichild (unused in function).

Suggested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1652282599-21643-1-git-send-email-quic_jhugo@quicinc.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Carl Vanderlip <quic_carlv@quicinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>