linux-kernel - [PATCH v3 0/4] Add support for updated vmware hypercall instruction

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Date:   Wed, 28 Aug 2019 10:03:49 +0200
From:   Thomas Hellström (VMware) 
        <thomas_os@...pmail.org>
To:     linux-kernel@...r.kernel.org
Cc:     pv-drivers@...are.com, linux-graphics-maintainer@...are.com,
        Thomas Hellström <thomas_os@...pmail.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: [PATCH v3 0/4] Add support for updated vmware hypercall instruction

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: <x86@...nel.org>

VMware has started using "vmcall" / "vmmcall" instead of an inl instruction
for the "backdoor" interface. This series detects support for those
instructions.
Outside of the platform code we use the "ALTERNATIVES" self-patching
mechanism similarly to how this is done with KVM.
Unfortunately we need two new x86 CPU feature flags for this, since we need
the default instruction to be "inl". IIRC the vmmouse driver is used by
other virtualization solutions than VMware, and those might break if
they encounter any of the other instructions.

v2:
- Address various style review comments
- Use mnemonics instead of bytecode in the ALTERNATIVE_2 macros
- Use vmcall / vmmcall also for the High-Bandwidth port calls
- Change the %edx argument to what vmcall / vmmcall expect (flags instead of
  port number). The port number is added in the default ALTERNATIVE_2 path.
- Ack to merge the vmmouse patch from Dmitry.
- Drop license update for now. Will get back with a freestanding patch.

v3:
- Address more style review comments
- Improve on documentation
- Remove an unnecessarily added include
- Ack to merge the vmwgfx patch from Dave.