From: Sean Christopherson <seanjc@google.com>
To: Ben Gardon <bgardon@google.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
David Matlack <dmatlack@google.com>,
Vipin Sharma <vipinsh@google.com>,
Ricardo Koller <ricarkol@google.com>
Subject: Re: [PATCH 09/21] KVM: x86/MMU: Move paging_tmpl.h includes to shadow_mmu.c
Date: Mon, 20 Mar 2023 11:41:28 -0700 [thread overview]
Message-ID: <ZBio2Cs7UrkkilTc@google.com> (raw)
In-Reply-To: <20230202182809.1929122-10-bgardon@google.com>
First off, I apologize for not giving this feedback in the RFC. I didn't think
too hard about the impliciations of moving paging_tmpl.h until I actually looked
at the code.
On Thu, Feb 02, 2023, Ben Gardon wrote:
> Move the integration point for paging_tmpl.h to shadow_mmu.c since
> paging_tmpl.h is ostensibly part of the Shadow MMU.
Ostensibly indeed. While a simple majority of paging_tmpl.h is indeed unique to
the shadow MMU, all of the guest walker code needs to exist independent of the
shadow MMU. And that code is signficant both in terms of lines of code, and
more importantly in terms of understanding its role in KVM at large.
This is essentially the same mess that eventually led the cpu_role vs. root_role
cleanup, and I think we should figure out a way to give paging_tmpl.h similar
treatment. E.g. split paging_tmpl.h itself in some way.
Unfortunately, this is a sticking point for me. If the code movement were minor
and/or cleaner in nature (definitely not your fault, simply the reality of the
code base), I might feel differently. But as it stands, there is a lot of churn
to get to an endpoint that has significant flaws.
So while I love the idea of separating the MMU implementations from the common
MMU logic, because the guest walker stuff is a lynchpin of sorts, e.g. splitting
out the guest walker logic could go hand-in-hand with reworking guest_mmu, I don't
want to take this series as is.
Sadly, as much as I'm itching to dive in and do a bit of exploration, I am woefully
short on bandwidth right now, so all I can do is say no. Sorry :-(
next prev parent reply other threads:[~2023-03-20 18:49 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-02 18:27 [PATCH 00/21] KVM: x86/MMU: Formalize the Shadow MMU Ben Gardon
2023-02-02 18:27 ` [PATCH 01/21] KVM: x86/mmu: Rename slot rmap walkers to add clarity and clean up code Ben Gardon
2023-02-02 18:27 ` [PATCH 02/21] KVM: x86/mmu: Replace comment with an actual lockdep assertion on mmu_lock Ben Gardon
2023-02-02 18:27 ` [PATCH 03/21] KVM: x86/mmu: Clean up mmu.c functions that put return type on separate line Ben Gardon
2023-02-02 18:27 ` [PATCH 04/21] KVM: x86/MMU: Add shadow_mmu.(c|h) Ben Gardon
2023-02-02 18:27 ` [PATCH 05/21] KVM: x86/MMU: Expose functions for the Shadow MMU Ben Gardon
2023-02-02 18:27 ` [PATCH 06/21] KVM: x86/mmu: Get rid of is_cpuid_PSE36() Ben Gardon
2023-03-20 18:51 ` Sean Christopherson
2023-02-02 18:27 ` [PATCH 07/21] KVM: x86/MMU: Move the Shadow MMU implementation to shadow_mmu.c Ben Gardon
2023-02-02 18:27 ` [PATCH 08/21] KVM: x86/MMU: Expose functions for paging_tmpl.h Ben Gardon
2023-02-02 18:27 ` [PATCH 09/21] KVM: x86/MMU: Move paging_tmpl.h includes to shadow_mmu.c Ben Gardon
2023-03-20 18:41 ` Sean Christopherson [this message]
2023-03-21 18:43 ` Ben Gardon
2023-02-02 18:27 ` [PATCH 10/21] KVM: x86/MMU: Clean up Shadow MMU exports Ben Gardon
2023-02-02 18:27 ` [PATCH 11/21] KVM: x86/MMU: Cleanup shrinker interface with Shadow MMU Ben Gardon
2023-02-04 13:52 ` kernel test robot
2023-02-04 19:10 ` kernel test robot
2023-02-02 18:28 ` [PATCH 12/21] KVM: x86/MMU: Clean up naming of exported Shadow MMU functions Ben Gardon
2023-02-02 18:28 ` [PATCH 13/21] KVM: x86/MMU: Fix naming on prepare / commit zap page functions Ben Gardon
2023-02-02 18:28 ` [PATCH 14/21] KVM: x86/MMU: Factor Shadow MMU wrprot / clear dirty ops out of mmu.c Ben Gardon
2023-02-02 18:28 ` [PATCH 15/21] KVM: x86/MMU: Remove unneeded exports from shadow_mmu.c Ben Gardon
2023-02-04 14:44 ` kernel test robot
2023-02-02 18:28 ` [PATCH 16/21] KVM: x86/MMU: Wrap uses of kvm_handle_gfn_range in mmu.c Ben Gardon
2023-02-02 18:28 ` [PATCH 17/21] KVM: x86/MMU: Add kvm_shadow_mmu_ to the last few functions in shadow_mmu.h Ben Gardon
2023-02-02 18:28 ` [PATCH 18/21] KVM: x86/mmu: Move split cache topup functions to shadow_mmu.c Ben Gardon
2023-02-02 18:28 ` [PATCH 19/21] KVM: x86/mmu: Move Shadow MMU part of kvm_mmu_zap_all() to shadow_mmu.h Ben Gardon
2023-02-02 18:28 ` [PATCH 20/21] KVM: x86/mmu: Move Shadow MMU init/teardown to shadow_mmu.c Ben Gardon
2023-02-02 18:28 ` [PATCH 21/21] KVM: x86/mmu: Split out Shadow MMU lockless walk begin/end Ben Gardon
2023-03-20 19:09 ` [PATCH 00/21] KVM: x86/MMU: Formalize the Shadow MMU Sean Christopherson
2023-03-23 23:02 ` Sean Christopherson
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