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Date:   Thu, 2 Nov 2023 12:14:13 +0100
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Subject: Re: [PATCH v13 12/35] KVM: Prepare for handling only shared mappings
 in mmu_notifier events
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To:     Binbin Wu <binbin.wu@linux.intel.com>,
        Sean Christopherson <seanjc@google.com>
Cc:     Marc Zyngier <maz@kernel.org>,
        Oliver Upton <oliver.upton@linux.dev>,
        Huacai Chen <chenhuacai@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Anup Patel <anup@brainfault.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>, kvm@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
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        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Xiaoyao Li <xiaoyao.li@intel.com>,
        Xu Yilun <yilun.xu@intel.com>,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Fuad Tabba <tabba@google.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Anish Moorthy <amoorthy@google.com>,
        David Matlack <dmatlack@google.com>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Isaku Yamahata <isaku.yamahata@intel.com>,
        =?UTF-8?B?TWlja2HDq2wgU2FsYcO8?= =?UTF-8?Q?n?= <mic@digikod.net>,
        Vlastimil Babka <vbabka@suse.cz>,
        Vishal Annapurve <vannapurve@google.com>,
        Ackerley Tng <ackerleytng@google.com>,
        Maciej Szmigiero <mail@maciej.szmigiero.name>,
        David Hildenbrand <david@redhat.com>,
        Quentin Perret <qperret@google.com>,
        Michael Roth <michael.roth@amd.com>,
        Wang <wei.w.wang@intel.com>,
        Liam Merwick <liam.merwick@oracle.com>,
        Isaku Yamahata <isaku.yamahata@gmail.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
References: <20231027182217.3615211-1-seanjc@google.com>
 <20231027182217.3615211-13-seanjc@google.com>
 <9963b77c-3a38-4f89-b21e-48d0fdda8f53@linux.intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
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On 11/2/23 06:59, Binbin Wu wrote:
> 
>> Add flags to "struct kvm_gfn_range" to let notifier events target
>> only shared and only private mappings, and write up the existing
>> mmu_notifier events to be shared-only (private memory is never
>> associated with a userspace virtual address, i.e. can't be reached
>> via mmu_notifiers).
>> 
>> Add two flags so that KVM can handle the three possibilities
>> (shared, private, and shared+private) without needing something
>> like a tri-state enum.
>
> I see the two flags are set/cleared in __kvm_handle_hva_range() in
> this patch and kvm_handle_gfn_range() from the later patch 13/35, but
> I didn't see they are used/read in this patch series if I didn't miss
> anything.  How are they supposed to be used in KVM?

They are going to be used by SNP/TDX patches.

Paolo