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Date:   Tue, 21 Mar 2023 14:38:22 -0700
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Subject: Re: [Patch v3 0/7] Optimize clear dirty log
From:   Sean Christopherson <seanjc@google.com>
To:     Vipin Sharma <vipinsh@google.com>
Cc:     pbonzini@redhat.com, bgardon@google.com, dmatlack@google.com,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, Mar 21, 2023, Sean Christopherson wrote:
> It won't.  MMU_WARN_ON() is dead code without manual modification to defi=
ne MMU_DEBUG.
> Part of the reason I used MMU_WARN_ON() was to remind myself to send a pa=
tch/series
> to overhaul MMU_WARN_ON[*].  My thought/hope is that a Kconfig will allow=
 developers
> and testers to run with a pile of assertions and sanity checks without im=
pacting
> the runtime overhead for production builds.
>=20
> [*] https://lore.kernel.org/all/Yz4Qi7cn7TWTWQjj@google.com/

Ugh, I'm definitely sending that patch, MMU_DEBUG has bitrotted and broken =
the
build yet again.

arch/x86/kvm/mmu/mmu.c: In function =E2=80=98kvm_mmu_free_shadow_page=E2=80=
=99:
arch/x86/kvm/mmu/mmu.c:1738:15: error: implicit declaration of function =E2=
=80=98is_empty_shadow_page=E2=80=99; did you mean =E2=80=98to_shadow_page=
=E2=80=99? [-Werror=3Dimplicit-function-declaration]
 1738 |  MMU_WARN_ON(!is_empty_shadow_page(sp->spt));
      |               ^~~~~~~~~~~~~~~~~~~~
include/asm-generic/bug.h:110:25: note: in definition of macro =E2=80=98WAR=
N_ON_ONCE=E2=80=99
  110 |  int __ret_warn_on =3D !!(condition);   \
      |                         ^~~~~~~~~
arch/x86/kvm/mmu/mmu.c:1738:2: note: in expansion of macro =E2=80=98MMU_WAR=
N_ON=E2=80=99
 1738 |  MMU_WARN_ON(!is_empty_shadow_page(sp->spt));
      |  ^~~~~~~~~~~