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When a vCPU is HLTed, interrupts with a priority below the processor priority (PPR) should not resume the vCPU while interrupts at or above the PPR should. With posted interrupts, bhyve maintains a bitmap of pending interrupts in PIR descriptor along with a single 'pending' bit. This bit is checked by a CPU running in guest mode at various places to determine if it should be checked. In addition, another CPU can force a CPU in guest mode to check for pending interrupts by sending an IPI to a special IDT vector reserved for this purpose. bhyve had a bug in that it would only notify a guest vCPU of an interrupt (e.g. by sending the special IPI or by resuming it if it was idle due to HLT) if an interrupt arrived that was higher priority than PPR and no interrupts were currently pending. This assumed that if the 'pending' bit was set, any needed notification was already in progress. However, if the first interrupt sent to a HLTed vCPU was lower priority than PPR and the second was higher than PPR, the first interrupt would set 'pending' but not notify the vCPU, and the second interrupt would not notify the vCPU because 'pending' was already set. To fix this, track the priority of pending interrupts in a separate per-vCPU bitmask and notify a vCPU anytime an interrupt arrives that is above PPR and higher than any previously-received interrupt. This was found and debugged in the bhyve port to SmartOS maintained by Joyent. Relevant SmartOS bugs with more background: https://smartos.org/bugview/OS-6829 https://smartos.org/bugview/OS-6930 https://smartos.org/bugview/OS-7354 Submitted by: Patrick Mooney <pmooney@pfmooney.com> Reviewed by: tychon, rgrimes Obtained from: SmartOS / Joyent MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D19299 |
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| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| stand | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| Makefile.libcompat | ||
| Makefile.sys.inc | ||
| ObsoleteFiles.inc | ||
| README | ||
| README.md | ||
| UPDATING | ||
FreeBSD Source:
This is the top level of the FreeBSD source directory. This file
was last revised on:
FreeBSD
FreeBSD is an operating system used to power modern servers, desktops, and embedded platforms. A large community has continually developed it for more than thirty years. Its advanced networking, security, and storage features have made FreeBSD the platform of choice for many of the busiest web sites and most pervasive embedded networking and storage devices.
For copyright information, please see the file COPYRIGHT in this directory. Additional copyright information also exists for some sources in this tree - please see the specific source directories for more information.
The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree. See build(7), config(8), https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html, and https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html for more information, including setting make(1) variables.
Source Roadmap:
bin System/user commands.
cddl Various commands and libraries under the Common Development
and Distribution License.
contrib Packages contributed by 3rd parties.
crypto Cryptography stuff (see crypto/README).
etc Template files for /etc.
gnu Various commands and libraries under the GNU Public License.
Please see gnu/COPYING* for more information.
include System include files.
kerberos5 Kerberos5 (Heimdal) package.
lib System libraries.
libexec System daemons.
release Release building Makefile & associated tools.
rescue Build system for statically linked /rescue utilities.
sbin System commands.
secure Cryptographic libraries and commands.
share Shared resources.
stand Boot loader sources.
sys Kernel sources.
sys/<arch>/conf Kernel configuration files. GENERIC is the configuration
used in release builds. NOTES contains documentation of
all possible entries.
tests Regression tests which can be run by Kyua. See tests/README
for additional information.
tools Utilities for regression testing and miscellaneous tasks.
usr.bin User commands.
usr.sbin System administration commands.
For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see:
https://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/current-stable.html