From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42477) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1anGTY-0005SR-0b for qemu-devel@nongnu.org; Mon, 04 Apr 2016 22:12:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1anGTT-0001by-14 for qemu-devel@nongnu.org; Mon, 04 Apr 2016 22:12:15 -0400 Date: Tue, 5 Apr 2016 12:12:01 +1000 From: Paul Mackerras Message-ID: <20160405021201.GA2663@yogo.paulus.ozlabs.org> References: <20160404164457.539a55f0@kryten> <57021123.6050506@ozlabs.ru> <20160404204346.1cf44df8@kryten> <20160404210928.0d9ae644@kryten> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160404210928.0d9ae644@kryten> Subject: Re: [Qemu-devel] [PATCH] spapr: Don't set the TM ibm, pa-features bit in PR KVM mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anton Blanchard Cc: Michael Neuling , Alexey Kardashevskiy , Michael Ellerman , Alexander Graf , qemu-devel@nongnu.org, qemu-ppc@nongnu.org, linuxppc-dev@lists.ozlabs.org, David Gibson On Mon, Apr 04, 2016 at 09:09:28PM +1000, Anton Blanchard wrote: > We don't support transactional memory in PR KVM, so don't tell > the OS that we do. This assumes PR KVM won't ever support TM, which is hopefully not true. If PR KVM does get TM support in future, then QEMU will have no clear way to know whether it needs to clear the pa-features bit or not. I think we need to define some way for the KVM implementation to tell qemu which of these kinds of CPU features it supports. However, we could defer implementing that mechanism until PR KVM does get support for TM, I guess. In that case this patch could go in now, though it seems slightly icky to be using the pvinfo stuff to distinguish PR from HV. Paul.