From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eduardo Habkost Subject: Re: kvm: RDTSCP on AMD Date: Mon, 10 Dec 2018 17:47:25 -0200 Message-ID: <20181210194725.GM4669@habkost.net> References: <20181210181328.GA762@zn.tnic> <20181210183730.GJ4669@habkost.net> <20181210184153.GB5482@zn.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Paolo Bonzini , =?iso-8859-1?Q?J=F6rg_R=F6del?= , Andre Przywara , kvm ML , lkml , Tom Lendacky To: Borislav Petkov Return-path: Content-Disposition: inline In-Reply-To: <20181210184153.GB5482@zn.tnic> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Mon, Dec 10, 2018 at 07:41:53PM +0100, Borislav Petkov wrote: > On Mon, Dec 10, 2018 at 04:37:30PM -0200, Eduardo Habkost wrote: > > It isn't as simply as reverting commit 33b5e8c03ae7, but we can > > surely re-add RDTSCP on pc-*-4.0 and newer. > > Sure. If you could only point me to an example how to add that to > pc-*-4.0 and newer, I'll gladly cook up a patch and test it. Sorry, I forgot to reply to this part. See commit 33b5e8c03ae7 for reference. The differences will be: * Instead of removing RDTSCP from builtin_x86_defs, you'll be adding it. * Instead of adding rdtscp=on entries to PC_COMPAT_2_4, you'll be adding rdtscp=off entries to PC_COMPAT_3_1. PC_COMPAT_3_1 is added by the patch that creates the 4.0 machine-types. You can find it on my machine-next branch at: http://github.com/ehabkost/qemu -- Eduardo