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Message-ID: <29baac45-7736-a28c-3b2d-2a6e45171b8b@intel.com>
Date:   Fri, 21 Jul 2023 23:42:04 +0800
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Subject: Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for
 guest-specific backing memory
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From:   Xiaoyao Li <xiaoyao.li@intel.com>
To:     Sean Christopherson <seanjc@google.com>,
        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>
Cc:     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>
References: <20230718234512.1690985-1-seanjc@google.com>
 <20230718234512.1690985-13-seanjc@google.com>
 <fdc155f5-041b-a1b1-15aa-8f970180a13a@intel.com>
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On 7/21/2023 11:05 PM, Xiaoyao Li wrote:
> On 7/19/2023 7:44 AM, Sean Christopherson wrote:
>> @@ -6255,12 +6298,17 @@ int kvm_init(unsigned vcpu_size, unsigned 
>> vcpu_align, struct module *module)
>>       if (r)
>>           goto err_async_pf;
>> +    r = kvm_gmem_init();
>> +    if (r)
>> +        goto err_gmem;
>> +
>>       kvm_chardev_ops.owner = module;
>>       kvm_preempt_ops.sched_in = kvm_sched_in;
>>       kvm_preempt_ops.sched_out = kvm_sched_out;
>>       kvm_init_debug();
>> +    kvm_gmem_init();
> 
> why kvm_gmem_init() needs to be called again? by mistake?

I'm sure it's a mistake.

I'm testing the gmem QEMU with this series. SW_PROTECTED_VM gets stuck 
in a loop in early OVMF code due to two shared page of OVMF get zapped 
and re-mapped infinitely. Removing the second call of kvm_gmem_init() 
can solve the issue, though I'm not sure about the reason.