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Date:   Fri, 9 Dec 2022 14:24:31 +0800
From:   Chao Peng <chao.p.peng@linux.intel.com>
To:     Fuad Tabba <tabba@google.com>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
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        Paolo Bonzini <pbonzini@redhat.com>,
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        Wanpeng Li <wanpengli@tencent.com>,
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        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
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        Naoya Horiguchi <naoya.horiguchi@nec.com>,
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        "Maciej S . Szmigiero" <mail@maciej.szmigiero.name>,
        Vlastimil Babka <vbabka@suse.cz>,
        Vishal Annapurve <vannapurve@google.com>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
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Subject: Re: [PATCH v10 5/9] KVM: Use gfn instead of hva for
 mmu_notifier_retry
Message-ID: <20221209062431.GA1342934@chaop.bj.intel.com>
Reply-To: Chao Peng <chao.p.peng@linux.intel.com>
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On Tue, Dec 06, 2022 at 03:48:50PM +0000, Fuad Tabba wrote:
...
 > >
> > > >          */
> > > > -       if (unlikely(kvm->mmu_invalidate_in_progress) &&
> > > > -           hva >= kvm->mmu_invalidate_range_start &&
> > > > -           hva < kvm->mmu_invalidate_range_end)
> > > > -               return 1;
> > > > +       if (unlikely(kvm->mmu_invalidate_in_progress)) {
> > > > +               /*
> > > > +                * Dropping mmu_lock after bumping mmu_invalidate_in_progress
> > > > +                * but before updating the range is a KVM bug.
> > > > +                */
> > > > +               if (WARN_ON_ONCE(kvm->mmu_invalidate_range_start == INVALID_GPA ||
> > > > +                                kvm->mmu_invalidate_range_end == INVALID_GPA))
> > >
> > > INVALID_GPA is an x86-specific define in
> > > arch/x86/include/asm/kvm_host.h, so this doesn't build on other
> > > architectures. The obvious fix is to move it to
> > > include/linux/kvm_host.h.
> >
> > Hmm, INVALID_GPA is defined as ZERO for x86, not 100% confident this is
> > correct choice for other architectures, but after search it has not been
> > used for other architectures, so should be safe to make it common.

As Yu posted a patch:
https://lore.kernel.org/all/20221209023622.274715-1-yu.c.zhang@linux.intel.com/

There is a GPA_INVALID in include/linux/kvm_types.h and I see ARM has already
been using it so sounds that is exactly what I need.

Chao
> 
> With this fixed,
> 
> Reviewed-by: Fuad Tabba <tabba@google.com>
> And the necessary work to port to arm64 (on qemu/arm64):
> Tested-by: Fuad Tabba <tabba@google.com>
> 
> Cheers,
> /fuad