From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sean Christopherson <sean.j.christopherson@intel.com>
Date: Tue, 03 Dec 2019 22:14:33 +0000
Subject: Re: [PATCH v3 00/15] KVM: Dynamically size memslot arrays
Message-Id: <20191203221433.GK19877@linux.intel.com>
List-Id: <kvm-ppc.vger.kernel.org>
References: <20191024230744.14543-1-sean.j.christopherson@intel.com>
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To: James Hogan <jhogan@kernel.org>, Paul Mackerras <paulus@ozlabs.org>, Christian Borntraeger <borntraeger@de.ibm.com>, Janosch Frank <frankja@linux.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>, Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>, Marc Zyngier <maz@kernel.org>
Cc: David Hildenbrand <david@redhat.com>, Cornelia Huck <cohuck@redhat.com>, Vitaly Kuznetsov <vkuznets@redhat.com>, Wanpeng Li <wanpengli@tencent.com>, Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>, James Morse <james.morse@arm.com>, Julien Thierry <julien.thierry.kdev@gmail.com>, Suzuki K Poulose <suzuki.poulose@arm.com>, linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Christoffer Dall <christoffer.dall@arm.com>

On Thu, Oct 24, 2019 at 04:07:29PM -0700, Sean Christopherson wrote:
> The end goal of this series is to dynamically size the memslot array so
> that KVM allocates memory based on the number of memslots in use, as
> opposed to unconditionally allocating memory for the maximum number of
> memslots.  On x86, each memslot consumes 88 bytes, and so with 2 address
> spaces of 512 memslots, each VM consumes ~90k bytes for the memslots.
> E.g. given a VM that uses a total of 30 memslots, dynamic sizing reduces
> the memory footprint from 90k to ~2.6k bytes.
> 
> The changes required to support dynamic sizing are relatively small,
> e.g. are essentially contained in patches 14/15 and 15/15.  Patches 1-13
> clean up the memslot code, which has gotten quite crusty, especially
> __kvm_set_memory_region().  The clean up is likely not strictly necessary
> to switch to dynamic sizing, but I didn't have a remotely reasonable
> level of confidence in the correctness of the dynamic sizing without first
> doing the clean up.
> 
> Christoffer, I added your Tested-by to the patches that I was confident
> would be fully tested based on the desription of what you tested.  Let me
> know if you disagree with any of 'em.
> 
> v3:
>   - Fix build errors on PPC and MIPS due to missed params during
>     refactoring [kbuild test robot].
>   - Rename the helpers for update_memslots() and add comments describing
>     the new algorithm and how it interacts with searching [Paolo].
>   - Remove the unnecessary and obnoxious warning regarding memslots being
>     a flexible array [Paolo].
>   - Fix typos in the changelog of patch 09/15 [Christoffer].
>   - Collect tags [Christoffer].
> 
> v2:
>   - Split "Drop kvm_arch_create_memslot()" into three patches to move
>     minor functional changes to standalone patches [Janosch].
>   - Rebase to latest kvm/queue (f0574a1cea5b, "KVM: x86: fix ...")
>   - Collect an Acked-by and a Reviewed-by

Paolo, do you want me to rebase this to the latest kvm/queue?