From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ram Pai Date: Wed, 23 Jan 2019 18:00:00 +0000 Subject: Re: [PATCH 04/13] KVM: PPC: Ultravisor: Use UV_WRITE_PATE ucall to register a PATE Message-Id: <20190123180000.GP6360@ram.ibm.com> List-Id: References: <1548172784-27414-5-git-send-email-linuxram@us.ibm.com> In-Reply-To: <1548172784-27414-5-git-send-email-linuxram@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kvm-ppc@vger.kernel.org On Wed, Jan 23, 2019 at 10:48:20AM +1100, Paul Mackerras wrote: > On Tue, Jan 22, 2019 at 07:59:35AM -0800, Ram Pai wrote: > > From: Michael Anderson > > > > The Nest_MMU needs to know the address of the Partition table (PT). > > However the PT is in secure memory, and nestMMU cannot access secure > > memory. Hence hypevisor will continue to use a Partition table of > > its own. It will have PATE entries for HV and for Normal virtual > > machines. The same entries are also in the UV's PT. The HV's PT > > is programmed with the nest MMU. > > This isn't a good patch description. It's confusing because it > doesn't start with the primary motivation of the patch - which is that > when running under an ultravisor, the ultravisor controls the real > partition table and has it in secure memory where the hypervisor can't > access it, and therefore we (the HV) have to do a ucall whenever we > want to update an entry. Once you have explained that, then you can > explain the secondary aspect of the patch, which is that the HV still > keeps a copy of its view of the partition table in normal memory so > that the nest MMU can access it. > > > Suggested-by: Ryan Grimm > > Signed-off-by: Madhavan Srinivasan > > [device node name to ibm,ultravisor] > > Signed-off-by: Michael Anderson > > Signed-off-by: Ram Pai > > If Michael Anderson wrote the patch and sent it to you, and you sent > it to the list, why is Maddy's signoff relevant? Was the original > version of the patch actually written by Maddy? Yes. this patch description needs a good amount work. A couple of related patches; some by Michael and some by me and some bug fixes by Maddy, were merged leading to this signoff cocktail and incoherent description. This was my first attempt to bring a logical order to our internal set of patches, which I agree has some more way to go. :( Thanks, RP