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Tue, 14 Jul 2020 05:31:26 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 009AB4C046; Tue, 14 Jul 2020 05:31:26 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CBCFA4C059; Tue, 14 Jul 2020 05:31:24 +0000 (GMT) Received: from in.ibm.com (unknown [9.79.210.191]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Tue, 14 Jul 2020 05:31:24 +0000 (GMT) Date: Tue, 14 Jul 2020 11:01:22 +0530 From: Bharata B Rao To: Paul Mackerras Subject: Re: [RFC PATCH v0 2/2] KVM: PPC: Book3S HV: Use H_RPT_INVALIDATE in nested KVM Message-ID: <20200714053122.GI7902@in.ibm.com> References: <20200703104420.21349-1-bharata@linux.ibm.com> <20200703104420.21349-3-bharata@linux.ibm.com> <20200709051803.GC2822576@thinks.paulus.ozlabs.org> <20200709090851.GD7902@in.ibm.com> <20200709100711.GA2961345@thinks.paulus.ozlabs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200709100711.GA2961345@thinks.paulus.ozlabs.org> X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-13_17:2020-07-13, 2020-07-13 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=1 malwarescore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 adultscore=0 spamscore=0 priorityscore=1501 mlxlogscore=999 phishscore=0 impostorscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007140034 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: bharata@linux.ibm.com Cc: aneesh.kumar@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com, kvm-ppc@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Jul 09, 2020 at 08:07:11PM +1000, Paul Mackerras wrote: > On Thu, Jul 09, 2020 at 02:38:51PM +0530, Bharata B Rao wrote: > > On Thu, Jul 09, 2020 at 03:18:03PM +1000, Paul Mackerras wrote: > > > On Fri, Jul 03, 2020 at 04:14:20PM +0530, Bharata B Rao wrote: > > > > In the nested KVM case, replace H_TLB_INVALIDATE by the new hcall > > > > H_RPT_INVALIDATE if available. The availability of this hcall > > > > is determined from "hcall-rpt-invalidate" string in ibm,hypertas-functions > > > > DT property. > > > > > > What are we going to use when nested KVM supports HPT guests at L2? > > > L1 will need to do partition-scoped tlbies with R=0 via a hypercall, > > > but H_RPT_INVALIDATE says in its name that it only handles radix > > > page tables (i.e. R=1). > > > > For L2 HPT guests, the old hcall is expected to work after it adds > > support for R=0 case? > > That was the plan. > > > The new hcall should be advertised via ibm,hypertas-functions only > > for radix guests I suppose. > > Well, the L1 hypervisor is a radix guest of L0, so it would have > H_RPT_INVALIDATE available to it? > > I guess the question is whether H_RPT_INVALIDATE is supposed to do > everything, that is, radix process-scoped invalidations, radix > partition-scoped invalidations, and HPT partition-scoped > invalidations. If that is the plan then we should call it something > different. Guess we are bit late now to rename it and include HPT in the scope. > > This patchset seems to imply that H_RPT_INVALIDATE is at least going > to be used for radix partition-scoped invalidations as well as radix > process-scoped invalidations. If you are thinking that in future when > we need HPT partition-scoped invalidations for a radix L1 hypervisor > running a HPT L2 guest, we are going to define a new hypercall for > that, I suppose that is OK, though it doesn't really seem necessary. Guess a new hcall would be the way forward to cover the HPT L2 guest requirements. Thanks for pointing this out. Regards, Bharata.