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Nikita Leshenko 0fc5a36dd6 KVM: x86: ioapic: Fix level-triggered EOI and IOAPIC reconfigure race
KVM uses ioapic_handled_vectors to track vectors that need to notify the
IOAPIC on EOI. The problem is that IOAPIC can be reconfigured while an
interrupt with old configuration is pending or running and
ioapic_handled_vectors only remembers the newest configuration;
thus EOI from the old interrupt is not delievered to the IOAPIC.

A previous commit db2bdcbbbd
("KVM: x86: fix edge EOI and IOAPIC reconfig race")
addressed this issue by adding pending edge-triggered interrupts to
ioapic_handled_vectors, fixing this race for edge-triggered interrupts.
The commit explicitly ignored level-triggered interrupts,
but this race applies to them as well:

1) IOAPIC sends a level triggered interrupt vector to VCPU0
2) VCPU0's handler deasserts the irq line and reconfigures the IOAPIC
   to route the vector to VCPU1. The reconfiguration rewrites only the
   upper 32 bits of the IOREDTBLn register. (Causes KVM to update
   ioapic_handled_vectors for VCPU0 and it no longer includes the vector.)
3) VCPU0 sends EOI for the vector, but it's not delievered to the
   IOAPIC because the ioapic_handled_vectors doesn't include the vector.
4) New interrupts are not delievered to VCPU1 because remote_irr bit
   is set forever.

Therefore, the correct behavior is to add all pending and running
interrupts to ioapic_handled_vectors.

This commit introduces a slight performance hit similar to
commit db2bdcbbbd ("KVM: x86: fix edge EOI and IOAPIC reconfig race")
for the rare case that the vector is reused by a non-IOAPIC source on
VCPU0. We prefer to keep solution simple and not handle this case just
as the original commit does.

Fixes: db2bdcbbbd ("KVM: x86: fix edge EOI and IOAPIC reconfig race")

Signed-off-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-11-17 13:20:17 +01:00
arch KVM: x86: ioapic: Fix level-triggered EOI and IOAPIC reconfigure race 2017-11-17 13:20:17 +01:00
block block/blk-mq.c: use kmalloc_array_node() 2017-11-15 18:21:02 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto kmemcheck: stop using GFP_NOTRACK and SLAB_NOTRACK 2017-11-15 18:21:04 -08:00
Documentation GICv4 Support for KVM/ARM for v4.15 2017-11-17 13:20:01 +01:00
drivers ARM: SoC driver updates for v4.15 2017-11-16 16:05:01 -08:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-11-16 12:50:35 -08:00
include GICv4 Support for KVM/ARM for v4.15 2017-11-17 13:20:01 +01:00
init Merge branch 'akpm' (patches from Andrew) 2017-11-15 19:42:40 -08:00
ipc License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kernel Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-11-16 12:20:15 -08:00
lib Driver core patches for 4.15-rc1 2017-11-16 08:55:30 -08:00
mm virtio, vhost, qemu: bugfixes, cleanups 2017-11-16 13:14:46 -08:00
net Merge branch 'akpm' (patches from Andrew) 2017-11-15 19:42:40 -08:00
samples media updates for v4.15-rc1 2017-11-15 20:30:12 -08:00
scripts main drm pull request for v4.15 2017-11-15 20:42:10 -08:00
security Modules updates for v4.15 2017-11-15 13:46:33 -08:00
sound sound updates for 4.15-rc1 2017-11-14 18:01:46 -08:00
tools First batch of KVM changes for 4.15 2017-11-16 13:00:24 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt GICv4 Support for KVM/ARM for v4.15 2017-11-17 13:20:01 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: move *.dtb and *.dtb.S patterns to the top-level .gitignore 2017-11-08 11:20:24 -06:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS ARM: SoC driver updates for v4.15 2017-11-16 16:05:01 -08:00
Makefile RISC-V Port for Linux 4.15 v9 2017-11-15 10:49:15 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.