From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mackerras Subject: Re: [PATCH 00/19] KVM: PPC: Book3S HV: add XIVE native exploitation mode Date: Wed, 6 Feb 2019 09:13:15 +1100 Message-ID: <20190205221315.GB29038@blackberry> References: <20190107184331.8429-1-clg@kaod.org> <20190122044654.GA15124@blackberry> <2f9b4420-ef90-20b8-d31b-dc547a6aa6b4@kaod.org> <06b7c4d2-72ba-ca4f-aded-789280798136@kaod.org> <20190204053610.GK1927@umbus.fritz.box> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, David Gibson To: =?iso-8859-1?Q?C=E9dric?= Le Goater Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+glppe-linuxppc-embedded-2=m.gmane.org@lists.ozlabs.org Sender: "Linuxppc-dev" List-Id: kvm.vger.kernel.org On Tue, Feb 05, 2019 at 12:31:28PM +0100, Cédric Le Goater wrote: > >>> As for nesting, I suggest for the foreseeable future we stick to XICS > >>> emulation in nested guests. > >> > >> ok. so no kernel_irqchip at all. hmm. > > I was confused with what Paul calls 'XICS emulation'. It's not the QEMU > XICS emulated device but the XICS-over-XIVE KVM device, the KVM XICS > device KVM uses when under a P9 processor. Actually there are two separate implementations of XICS emulation in KVM. The first (older) one is almost entirely a software emulation but does have some cases where it accesses an underlying XICS device in order to make some things faster (IPIs and pass-through of a device interrupt to a guest). The other, newer one is the XICS-on-XIVE emulation that Ben wrote, which uses the XIVE hardware pretty heavily. My patch was about making the the older code work when there is no XICS available to the host. Paul.