[siemens/jailhouse] 841d8f: x86: Be graceful with invalid MSI target addresses

[GitHub]

Branch: refs/heads/next
Home: https://github.com/siemens/jailhouse
Commit: 841d8f3c5fa4c0124fd8a4e1bd71e410e82fb09d
https://github.com/siemens/jailhouse/commit/841d8f3c5fa4c0124fd8a4e1bd71e410e82fb09d
Author: Jan Kiszka <jan.k...@siemens.com>
Date: 2017-01-17 (Tue, 17 Jan 2017)

Changed paths:
M hypervisor/arch/x86/pci.c

Log Message:
-----------
x86: Be graceful with invalid MSI target addresses

Linux seems to write zeros to MSI registers when unregistering an MSI
interrupt:

[...]
pci_bus_write_config_dword+0x14/0x20
__pci_write_msi_msg+0xcc/0x130
pci_msi_domain_write_msg+0x1d/0x20
msi_domain_deactivate+0x28/0x30 <-- this writes zeros
irq_domain_deactivate_irq+0x28/0x40
irq_shutdown+0x39/0x70
__free_irq+0x1ee/0x290
free_irq+0x34/0x80
tg3_test_interrupt+0x3f/0x230
tg3_start+0xfa3/0x1130
[...]
(taken with 4.9-rt)

Let's check if the target address actually matches the MSI address space
and, if not, simply declare the vector invalid. That will block it from
being used, raising an IOMMU runtime error at most when the device
should fire nevertheless. But we no longer panic the writer.

Signed-off-by: Jan Kiszka <jan.k...@siemens.com>
Tested-by: Rajiv Vaidyanath <Rajiv.Va...@ccur.com>