tree 2ab047866f0d6c6bd91e0f236e816d8d0a6157e5
parent b94178b239d797c204b045c6a0b77c43cbe82f8f
author Joerg Roedel <jroedel@suse.de> 1567759194 +0200
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1569042862 +0200

iommu/amd: Fix race in increase_address_space()

[ Upstream commit 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 ]

After the conversion to lock-less dma-api call the
increase_address_space() function can be called without any
locking. Multiple CPUs could potentially race for increasing
the address space, leading to invalid domain->mode settings
and invalid page-tables. This has been happening in the wild
under high IO load and memory pressure.

Fix the race by locking this operation. The function is
called infrequently so that this does not introduce
a performance regression in the dma-api path again.

Reported-by: Qian Cai <cai@lca.pw>
Fixes: 256e4621c21a ('iommu/amd: Make use of the generic IOVA allocator')
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>