From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [PATCH 06/19] KVM: PPC: Book3S HV: add a GET_ESB_FD control to the XIVE native device Date: Thu, 7 Feb 2019 13:49:50 +1100 Message-ID: <20190207024950.GA22661@umbus.fritz.box> References: <20190107184331.8429-1-clg@kaod.org> <20190107184331.8429-7-clg@kaod.org> <20190204044531.GB1927@umbus.fritz.box> <69791b73-f93e-6957-92e8-5b8620b87731@kaod.org> <20190205052822.GE22661@umbus.fritz.box> <4d565738-a99b-0333-8533-037677358faa@kaod.org> <20190206012308.GP22661@umbus.fritz.box> <1745dd9f-2927-cae6-e8da-c350b0bd0a66@kaod.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="+9kyDs7IugQ0lHaC" Cc: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, Paul Mackerras , linuxppc-dev@lists.ozlabs.org To: =?iso-8859-1?Q?C=E9dric?= Le Goater Return-path: Content-Disposition: inline In-Reply-To: <1745dd9f-2927-cae6-e8da-c350b0bd0a66@kaod.org> 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 --+9kyDs7IugQ0lHaC Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 06, 2019 at 08:21:10AM +0100, C=E9dric Le Goater wrote: > On 2/6/19 2:23 AM, David Gibson wrote: > > On Tue, Feb 05, 2019 at 01:55:40PM +0100, C=E9dric Le Goater wrote: > >> On 2/5/19 6:28 AM, David Gibson wrote: > >>> On Mon, Feb 04, 2019 at 12:30:39PM +0100, C=E9dric Le Goater wrote: > >>>> On 2/4/19 5:45 AM, David Gibson wrote: > >>>>> On Mon, Jan 07, 2019 at 07:43:18PM +0100, C=E9dric Le Goater wrote: > >>>>>> This will let the guest create a memory mapping to expose the ESB = MMIO > >>>>>> regions used to control the interrupt sources, to trigger events, = to > >>>>>> EOI or to turn off the sources. > >>>>>> > >>>>>> Signed-off-by: C=E9dric Le Goater > >>>>>> --- > >>>>>> arch/powerpc/include/uapi/asm/kvm.h | 4 ++ > >>>>>> arch/powerpc/kvm/book3s_xive_native.c | 97 ++++++++++++++++++++++= +++++ > >>>>>> 2 files changed, 101 insertions(+) > >>>>>> > >>>>>> diff --git a/arch/powerpc/include/uapi/asm/kvm.h b/arch/powerpc/in= clude/uapi/asm/kvm.h > >>>>>> index 8c876c166ef2..6bb61ba141c2 100644 > >>>>>> --- a/arch/powerpc/include/uapi/asm/kvm.h > >>>>>> +++ b/arch/powerpc/include/uapi/asm/kvm.h > >>>>>> @@ -675,4 +675,8 @@ struct kvm_ppc_cpu_char { > >>>>>> #define KVM_XICS_PRESENTED (1ULL << 43) > >>>>>> #define KVM_XICS_QUEUED (1ULL << 44) > >>>>>> =20 > >>>>>> +/* POWER9 XIVE Native Interrupt Controller */ > >>>>>> +#define KVM_DEV_XIVE_GRP_CTRL 1 > >>>>>> +#define KVM_DEV_XIVE_GET_ESB_FD 1 > >>>>> > >>>>> Introducing a new FD for ESB and TIMA seems overkill. Can't you get > >>>>> to both with an mmap() directly on the xive device fd? Using the > >>>>> offset to distinguish which one to map, obviously. > >>>> > >>>> The page offset would define some sort of user API. It seems feasibl= e. > >>>> But I am not sure this would be practical in the future if we need t= o=20 > >>>> tune the length. > >>> > >>> Um.. why not? I mean, yes the XIVE supports rather a lot of > >>> interrupts, but we have 64-bits of offset we can play with - we can > >>> leave room for billions of ESB slots and still have room for billions > >>> of VPs. > >> > >> So the first 4 pages could be the TIMA pages and then would come =20 > >> the pages for the interrupt ESBs. I think that we can have different= =20 > >> vm_fault handler for each mapping. > >=20 > > Um.. no, I'm saying you don't need to tightly pack them. So you could > > have the ESB pages at 0, the TIMA at, say offset 2^60. >=20 > Well, we know that the TIMA is 4 pages wide and is "directly" related > with the KVM interrupt device. So being at offset 0 seems a good idea. > While the ESB segment is of a variable size depending on the number > of IRQs and it can come after I think. >=20 > >> I wonder how this will work out with pass-through. As Paul said in=20 > >> a previous email, it would be better to let QEMU request a new=20 > >> mapping to handle the ESB pages of the device being passed through. > >> I guess this is not a special case, just another offset and length. > >=20 > > Right, if we need multiple "chunks" of ESB pages we can given them > > each their own terabyte or several. No need to be stingy with address > > space. >=20 > You can not put them anywhere. They should map the same interrupt range > of ESB pages, overlapping with the underlying segment of IPI ESB pages.= =20 I don't really follow what you're saying here. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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