tree dffcad69eeacefe08795843f456e80223478bb01
parent bea6c33ca17c85c76e8455fb86e38036bdb2a928
author Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> 1587742279 +0100
committer Will Deacon <will@kernel.org> 1587747504 +0100

vfio: fix multi-MSI vector handling

A PCI device with a MSI capability enabling Multiple MSI messages
(through the Multiple Message Enable field in the Message Control
register[6:4]) is expected to drive the Message Data lower bits (number
determined by the number of selected vectors) to generate the
corresponding MSI messages writes on the PCI bus.

Therefore, KVM expects the MSI data lower bits (a number of
bits that depend on bits [6:4] of the Message Control
register - which in turn control the number of vectors
allocated) to be set-up by kvmtool while programming the
MSI IRQ routing entries to make sure the MSI entries can
actually be demultiplexed by KVM and IRQ routes set-up
accordingly so that when an actual HW fires KVM can
route it to the correct entry in the interrupt controller
(and set-up a correct passthrough route for directly
injected interrupt).

Current kvmtool code does not set-up Message data entries
correctly for multi-MSI vectors - the data field is left
as programmed in the MSI capability by the guest for all
vector entries, triggering IRQs misrouting.

Fix it.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
Signed-off-by: Will Deacon <will@kernel.org>