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Date:   Tue, 6 Dec 2022 22:34:11 -0800
From:   Isaku Yamahata <isaku.yamahata@gmail.com>
To:     Chao Peng <chao.p.peng@linux.intel.com>
Cc:     Fuad Tabba <tabba@google.com>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
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Subject: Re: [PATCH v10 5/9] KVM: Use gfn instead of hva for
 mmu_notifier_retry
Message-ID: <20221207063411.GB3632095@ls.amr.corp.intel.com>
References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com>
 <20221202061347.1070246-6-chao.p.peng@linux.intel.com>
 <CA+EHjTy5+Ke_7Uh72p--H9kGcE-PK4EVmp7ym6Q1-PO28u6CCQ@mail.gmail.com>
 <20221206115623.GB1216605@chaop.bj.intel.com>
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On Tue, Dec 06, 2022 at 07:56:23PM +0800,
Chao Peng <chao.p.peng@linux.intel.com> 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.

INVALID_GPA is defined as all bit 1.  Please notice "~" (tilde).

#define INVALID_GPA (~(gpa_t)0)
-- 
Isaku Yamahata <isaku.yamahata@gmail.com>