From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH] PPC: Enable lightweight exits again Date: Wed, 6 Jan 2010 06:54:56 -0200 Message-ID: <20100106085456.GD3966@amt.cnet> References: <1262639965-21489-1-git-send-email-agraf@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kvm-ppc To: Alexander Graf Return-path: Content-Disposition: inline In-Reply-To: <1262639965-21489-1-git-send-email-agraf-l3A5Bk7waGM@public.gmane.org> Sender: kvm-ppc-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: kvm.vger.kernel.org On Mon, Jan 04, 2010 at 10:19:25PM +0100, Alexander Graf wrote: > The PowerPC C ABI defines that registers r14-r31 need to be preserved across > function calls. Since our exit handler is written in C, we can make use of that > and don't need to reload r14-r31 on every entry/exit cycle. > > This technique is also used in the BookE code and is called "lightweight exits" > there. To follow the tradition, it's called the same in Book3S. > > So far this optimization was disabled though, as the code didn't do what it was > expected to do, but failed to work. > > This patch fixes and enables lightweight exits again. > > Signed-off-by: Alexander Graf Applied, thanks.