From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= Subject: Re: [PATCH 08/19] KVM: PPC: Book3S HV: add a VC_BASE control to the XIVE native device Date: Mon, 4 Feb 2019 16:36:16 +0100 Message-ID: <04d4acf7-978f-fb40-a64b-b6df3ecc8a5e@kaod.org> References: <20190107184331.8429-1-clg@kaod.org> <20190107184331.8429-9-clg@kaod.org> <20190122051430.GE15124@blackberry> <8c45581e-466e-a390-e9cd-a06b5939d2af@kaod.org> <20190204044933.GC1927@umbus.fritz.box> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org To: David Gibson Return-path: In-Reply-To: <20190204044933.GC1927@umbus.fritz.box> Content-Language: en-US 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 2/4/19 5:49 AM, David Gibson wrote: > On Wed, Jan 23, 2019 at 05:56:26PM +0100, Cédric Le Goater wrote: >> On 1/22/19 6:14 AM, Paul Mackerras wrote: >>> On Mon, Jan 07, 2019 at 07:43:20PM +0100, Cédric Le Goater wrote: >>>> The ESB MMIO region controls the interrupt sources of the guest. QEMU >>>> will query an fd (GET_ESB_FD ioctl) and map this region at a specific >>>> address for the guest to use. The guest will obtain this information >>>> using the H_INT_GET_SOURCE_INFO hcall. To inform KVM of the address >>>> setting used by QEMU, add a VC_BASE control to the KVM XIVE device >>> >>> This needs a little more explanation. I *think* the only way this >>> gets used is that it gets returned to the guest by the new >>> hypercalls. If that is indeed the case it would be useful to mention >>> that in the patch description, because otherwise taking a value that >>> userspace provides and which looks like it is an address, and not >>> doing any validation on it, looks a bit scary. >> >> I think we have solved this problem in another email thread. >> >> The H_INT_GET_SOURCE_INFO hcall does not need to be implemented in KVM >> as all the source information should already be available in QEMU. In >> that case, there is no need to inform KVM of where the ESB pages are >> mapped in the guest address space. So we don't need that extra control >> on the KVM device. This is good news. > > Ah, good to hear. I thought this looked strange. yes. I didn't know which path to choose between HV real mode, HV, QEMU. It's clarified now. But now, we have nested, and this is adding quite a bit of strangeness to the hcall possibilities. C.