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Date:   Wed, 19 Jul 2023 07:16:54 -0700
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Subject: Re: [RFC PATCH v11 07/29] KVM: Add KVM_EXIT_MEMORY_FAULT exit
From:   Sean Christopherson <seanjc@google.com>
To:     Yuan Yao <yuan.yao@linux.intel.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>, 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>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Paul Moore <paul@paul-moore.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>, kvm@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
        linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Fuad Tabba <tabba@google.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Vishal Annapurve <vannapurve@google.com>,
        Ackerley Tng <ackerleytng@google.com>,
        Maciej Szmigiero <mail@maciej.szmigiero.name>,
        Vlastimil Babka <vbabka@suse.cz>,
        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>
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On Wed, Jul 19, 2023, Yuan Yao wrote:
> On Tue, Jul 18, 2023 at 04:44:50PM -0700, Sean Christopherson wrote:
> > From: Chao Peng <chao.p.peng@linux.intel.com>
> >
> > This new KVM exit allows userspace to handle memory-related errors. It
> > indicates an error happens in KVM at guest memory range [gpa, gpa+size).
> > The flags includes additional information for userspace to handle the
> > error. Currently bit 0 is defined as 'private memory' where '1'
> > indicates error happens due to private memory access and '0' indicates
> > error happens due to shared memory access.
> 
> Now it's bit 3:

Yeah, I need to update (or write) a lot of changelogs.

> #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1ULL << 3)
> 
> I remember some other attributes were introduced in v10 yet:
> 
> #define KVM_MEMORY_ATTRIBUTE_READ              (1ULL << 0)
> #define KVM_MEMORY_ATTRIBUTE_WRITE             (1ULL << 1)
> #define KVM_MEMORY_ATTRIBUTE_EXECUTE           (1ULL << 2)
> #define KVM_MEMORY_ATTRIBUTE_PRIVATE           (1ULL << 3)
> 
> So KVM_MEMORY_EXIT_FLAG_PRIVATE changed to bit 3 due to above things,
> or other reason ? (Sorry I didn't follow v10 too much before).

Yep, I want to reserve space for the RWX bits.