Date:   Tue, 23 Nov 2021 22:24:20 +0800
From:   Chao Peng <chao.p.peng@linux.intel.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
        qemu-devel@nongnu.org, Jonathan Corbet <corbet@lwn.net>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
        Hugh Dickins <hughd@google.com>,
        Jeff Layton <jlayton@kernel.org>,
        "J . Bruce Fields" <bfields@fieldses.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        luto@kernel.org, john.ji@intel.com, susie.li@intel.com,
        jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com,
        david@redhat.com
Subject: Re: [RFC v2 PATCH 09/13] KVM: Introduce kvm_memfd_invalidate_range
Message-ID: <20211123142420.GB32088@chaop.bj.intel.com>
Reply-To: Chao Peng <chao.p.peng@linux.intel.com>
References: <20211119134739.20218-1-chao.p.peng@linux.intel.com>
 <20211119134739.20218-10-chao.p.peng@linux.intel.com>
 <4041d98a-23df-e9ed-b245-5edd7151fec5@redhat.com>
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On Tue, Nov 23, 2021 at 09:46:34AM +0100, Paolo Bonzini wrote:
> On 11/19/21 14:47, Chao Peng wrote:
> > +
> > +	/* Prevent memslot modification */
> > +	spin_lock(&kvm->mn_invalidate_lock);
> > +	kvm->mn_active_invalidate_count++;
> > +	spin_unlock(&kvm->mn_invalidate_lock);
> > +
> > +	ret = __kvm_handle_useraddr_range(kvm, &useraddr_range);
> > +
> > +	spin_lock(&kvm->mn_invalidate_lock);
> > +	kvm->mn_active_invalidate_count--;
> > +	spin_unlock(&kvm->mn_invalidate_lock);
> > +
> 
> 
> You need to follow this with a rcuwait_wake_up as in
> kvm_mmu_notifier_invalidate_range_end.

Oh right.

> 
> It's probably best if you move the manipulations of
> mn_active_invalidate_count from kvm_mmu_notifier_invalidate_range_* to two
> separate functions.

Will do.

> 
> Paolo