Sean Christopherson 0f65a9d337 KVM: VMX: Don't do full kick when triggering posted interrupt "fails"
Replace the full "kick" with just the "wake" in the fallback path when
triggering a virtual interrupt via a posted interrupt fails because the
guest is not IN_GUEST_MODE.  If the guest transitions into guest mode
between the check and the kick, then it's guaranteed to see the pending
interrupt as KVM syncs the PIR to IRR (and onto GUEST_RVI) after setting
IN_GUEST_MODE.  Kicking the guest in this case is nothing more than an
unnecessary VM-Exit (and host IRQ).

Opportunistically update comments to explain the various ordering rules
and barriers at play.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211208015236.1616697-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-01-19 12:14:45 -05:00
2022-01-09 14:55:34 -08:00

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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