7a56b81c47
ACPI tables aren't available if Linux runs as guest of the hypervisor Jailhouse. This makes the 8250 driver probe for all platform UARTs as it assumes that all UARTs are present in case of !ACPI. Jailhouse will stop execution of Linux guest due to port access violation. So far, these access violations were solved by tuning the 8250.nr_uarts cmdline parameter, but this has limitations: Only consecutive platform UARTs can be mapped to Linux, and only in the sequence 0x3f8, 0x2f8, 0x3e8, 0x2e8. Beginning from setup_data version 2, Jailhouse will place information of available platform UARTs in setup_data. This allows for selective activation of platform UARTs. Query setup_data version and only activate available UARTS. This patch comes with backward compatibility, and will still support older setup_data versions. In case of older setup_data versions, Linux falls back to the old behaviour. Signed-off-by: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com> Cc: Baoquan He <bhe@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: jailhouse-dev@googlegroups.com Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20191010102102.421035-3-ralf.ramsauer@oth-regensburg.de
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.