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([2a04:ee41:4:31cb:e591:1e1e:abde:a8f1]) by smtp.gmail.com with ESMTPSA id v16-20020a05620a441000b006ceafb1aa92sm8124430qkp.96.2022.09.18.09.18.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 18 Sep 2022 09:18:26 -0700 (PDT) Message-ID: Date: Sun, 18 Sep 2022 18:18:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [RFC PATCH 9/9] kvm_main.c: handle atomic memslot update Content-Language: en-US To: "Yang, Weijiang" , kvm@vger.kernel.org Cc: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , David Hildenbrand , Maxim Levitsky , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org References: <20220909104506.738478-1-eesposit@redhat.com> <20220909104506.738478-10-eesposit@redhat.com> <7e64d472-fbce-6640-033a-51b8906b7924@intel.com> From: Emanuele Giuseppe Esposito In-Reply-To: <7e64d472-fbce-6640-033a-51b8906b7924@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 13/09/2022 um 04:30 schrieb Yang, Weijiang: > > On 9/9/2022 6:45 PM, Emanuele Giuseppe Esposito wrote: >> When kvm_vm_ioctl_set_memory_region_list() is invoked, we need >> to make sure that all memslots are updated in the inactive list >> and then swap (preferreably only once) the lists, so that all >> changes are visible immediately. > [...] >> +static int kvm_vm_ioctl_set_memory_region_list(struct kvm *kvm, >> +               struct kvm_userspace_memory_region_list *list, >> +               struct kvm_userspace_memory_region_entry __user *mem_arg) >> +{ >> +    struct kvm_userspace_memory_region_entry *mem, *m_iter; >> +    struct kvm_userspace_memory_region *mem_region; >> +    struct kvm_internal_memory_region_list *batch, *b_iter; >> +    int i, r = 0; >> +    bool *as_to_swap; >> + >> +    /* TODO: limit the number of mem to a max? */ >> + >> +    if (!list->nent) >> +        return r; >> + >> +    mem = vmemdup_user(mem_arg, array_size(sizeof(*mem), list->nent)); >> +    if (IS_ERR(mem)) { >> +        r = PTR_ERR(mem); >> +        goto out; >> +    } > > IMO, it's more natural to dup the user memory at the first place, i.e., > kvm_vm_ioctl, > > it also makes the outlets shorter. > I followed the same pattern as kvm_vcpu_ioctl_set_cpuid2, which performs the user memory dup inside the call :) I see your point but I guess it's better to keep all ioctl implementations similar. Thank you, Emanuele