Re: [PATCH 2/4] x86/vmware: Add a header file for hypercall definitions

From: Borislav Petkov
Date: Mon Aug 19 2019 - 02:25:13 EST

On Mon, Aug 19, 2019 at 12:28:05AM +0200, Thomas HellstrÃm (VMware) wrote:
> Unfortunately we can't use it, because it's unconditionally set on AMD even
> if the VMware hypervisor
> doesn't support it (by version or by configuration).

AMD sets it because they don't support VMCALL. Nothing stops us from
making that conditional depending on what the hypervisor can/supports.
I'm thinking it would be even cleaner if we use those two flags:


to denote hw support for either one or the other instruction and switch
accordingly. Just like KVM does.

In your case, the HV would set the preferred flag in
arch/x86/kernel/cpu/vmware.c - just like the others do in their
respective CPU init files - and the alternatives code would switch to it
when it runs.

Or is there more? :)



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