47bea873cf
The Intel IOMMU has an MSI-like configuration for its interrupt, but it isn't really MSI. So it gets to abuse the high 32 bits of the address, and puts the high 24 bits of the extended APIC ID there. This isn't something that can be used in the general case for real MSIs, since external devices using the high bits of the address would be performing writes to actual memory space above 4GiB, not targeted at the APIC. Factor the hack out and allow it only to be used when appropriate, adding a WARN_ON_ONCE() if other MSIs are targeted at an unreachable APIC ID. That should never happen since the compatibility MSI messages are not used when Interrupt Remapping is enabled. The x2apic_enabled() check isn't needed because Linux won't bring up CPUs with higher APIC IDs unless IR and x2apic are enabled anyway. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20201024213535.443185-3-dwmw2@infradead.org |
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| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.