Sean Christopherson 9ca0c1a126 KVM: VMX: Delete ancient pr_warn() about KVM_SET_TSS_ADDR not being set
Delete KVM's printk about KVM_SET_TSS_ADDR not being called.  When the
printk was added by commit 776e58ea3d ("KVM: unbreak userspace that does
not sets tss address"), KVM also stuffed a "hopefully safe" value, i.e.
the message wasn't purely informational.  For reasons unknown, ostensibly
to try and help people running outdated qemu-kvm versions, the message got
left behind when KVM's stuffing was removed by commit 4918c6ca68
("KVM: VMX: Require KVM_SET_TSS_ADDR being called prior to running a VCPU").

Today, the message is completely nonsensical, as it has been over a decade
since KVM supported userspace running a Real Mode guest, on a CPU without
unrestricted guest support, without doing KVM_SET_TSS_ADDR before KVM_RUN.
I.e. KVM's ABI has required KVM_SET_TSS_ADDR for 10+ years.

To make matters worse, the message is prone to false positives as it
triggers when simply *creating* a vCPU due to RESET putting vCPUs into
Real Mode, even when the user has no intention of ever *running* the vCPU
in a Real Mode.  E.g. KVM selftests stuff 64-bit mode and never touch Real
Mode, but trigger the message even though they run just fine without
doing KVM_SET_TSS_ADDR.  Creating "dummy" vCPUs, e.g. to probe features,
can also trigger the message.  In both scenarios, the message confuses
users and falsely implies that they've done something wrong.

Reported-by: Thorsten Glaser <t.glaser@tarent.de>
Closes: https://lkml.kernel.org/r/f1afa6c0-cde2-ab8b-ea71-bfa62a45b956%40tarent.de
Link: https://lore.kernel.org/r/20230815174215.433222-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-25 09:05:56 -07:00
2022-09-28 09:02:20 +02:00
2023-07-16 15:10:37 -07:00

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.
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