Re: [Kernel 6.12.17] [PowerPC e5500] KVM HV compilation error

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Mar 05, 2025 at 06:53:19AM -0800, Sean Christopherson wrote:
> On Wed, Mar 05, 2025, Greg KH wrote:
> > On Wed, Mar 05, 2025 at 03:14:13PM +0100, Christian Zigotzky wrote:
> > > Hi All,
> > > 
> > > The stable long-term kernel 6.12.17 cannot compile with KVM HV support for e5500 PowerPC machines anymore.
> > > 
> > > Bug report: https://github.com/chzigotzky/kernels/issues/6
> > > 
> > > Kernel config: https://github.com/chzigotzky/kernels/blob/6_12/configs/x5000_defconfig
> > > 
> > > Error messages:
> > > 
> > > arch/powerpc/kvm/e500_mmu_host.c: In function 'kvmppc_e500_shadow_map':
> > > arch/powerpc/kvm/e500_mmu_host.c:447:9: error: implicit declaration of function '__kvm_faultin_pfn' [-Werror=implicit-function-declaration]
> > >    pfn = __kvm_faultin_pfn(slot, gfn, FOLL_WRITE, NULL, &page);
> > >          ^~~~~~~~~~~~~~~~~
> > >   CC      kernel/notifier.o
> > > arch/powerpc/kvm/e500_mmu_host.c:500:2: error: implicit declaration of function 'kvm_release_faultin_page'; did you mean 'kvm_read_guest_page'? [-Werror=implicit-function-declaration]
> > >   kvm_release_faultin_page(kvm, page, !!ret, writable);
> > > 
> > > After that, I compiled it without KVM HV support.
> > > 
> > > Kernel config: https://github.com/chzigotzky/kernels/blob/6_12/configs/e5500_defconfig
> > > 
> > > Please check the error messages.
> > 
> > Odd, what commit caused this problem?  Any hint as to what commit is
> > missing to fix it?
> 
> 833f69be62ac.  It most definitely should be reverted.  The "dependency" for commit
> 87ecfdbc699c ("KVM: e500: always restore irqs") is a superficial code conflict.
> 
> Oof.  The same buggy patch was queue/proposed for all stable trees from 5.4 onward,
> but it look like it only landed in 6.1, 6.6, and 6.12.  I'll send reverts.
> 
> commit 833f69be62ac366b5c23b4a6434389e470dd5c7f
> Author:     Sean Christopherson <seanjc@google.com>
> AuthorDate: Thu Oct 10 11:23:56 2024 -0700
> Commit:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> CommitDate: Mon Feb 17 10:04:56 2025 +0100
> 
>     KVM: PPC: e500: Use __kvm_faultin_pfn() to handle page faults
>     
>     [ Upstream commit 419cfb983ca93e75e905794521afefcfa07988bb ]
>     
>     Convert PPC e500 to use __kvm_faultin_pfn()+kvm_release_faultin_page(),
>     and continue the inexorable march towards the demise of
>     kvm_pfn_to_refcounted_page().
>     
>     Signed-off-by: Sean Christopherson <seanjc@google.com>
>     Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
>     Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>     Message-ID: <20241010182427.1434605-55-seanjc@google.com>
>     Stable-dep-of: 87ecfdbc699c ("KVM: e500: always restore irqs")
>     Signed-off-by: Sasha Levin <sashal@kernel.org>

All now reverted, sorry about that.

greg k-h