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[209.132.183.28]) by mx.google.com with ESMTPS id j90si134855qtd.27.2019.02.01.22.57.54 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 01 Feb 2019 22:57:54 -0800 (PST) Received-SPF: pass (google.com: domain of peterx@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of peterx@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 022E989AE6; Sat, 2 Feb 2019 06:57:53 +0000 (UTC) Received: from xz-x1 (ovpn-12-23.pek2.redhat.com [10.72.12.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B6F7C5C20D; Sat, 2 Feb 2019 06:57:43 +0000 (UTC) Date: Sat, 2 Feb 2019 14:57:41 +0800 From: Peter Xu To: Fengguang Wu Cc: Andrew Morton , Linux Memory Management List , Nikita Leshenko , Christian Borntraeger , kvm@vger.kernel.org, LKML , Fan Du , Yao Yuan , Peng Dong , Huang Ying , Liu Jingqi , Dong Eddie , Dave Hansen , Zhang Yi , Dan Williams , Paolo Bonzini Subject: Re: [RFC][PATCH v2 14/21] kvm: register in mm_struct Message-ID: <20190202065741.GA1011@xz-x1> References: <20181226131446.330864849@intel.com> <20181226133351.894160986@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181226133351.894160986@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Sat, 02 Feb 2019 06:57:53 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Dec 26, 2018 at 09:15:00PM +0800, Fengguang Wu wrote: > VM is associated with an address space and not a specific thread. > > >From Documentation/virtual/kvm/api.txt: > Only run VM ioctls from the same process (address space) that was used > to create the VM. Hi, Fengguang, AFAIU the commit message only explains why a kvm object needs to bind to a single mm object (say, the reason why there is kvm->mm) however not the reverse (say, the reason why there is mm->kvm), while the latter is what this patch really needs? I'm thinking whether it's legal for multiple VMs to run on a single mm address space. I don't see a limitation so far but it's very possible I am just missing something there (if there is, IMHO they might be something nice to put into the commit message?). Thanks, > > CC: Nikita Leshenko > CC: Christian Borntraeger > Signed-off-by: Fengguang Wu > --- > include/linux/mm_types.h | 11 +++++++++++ > virt/kvm/kvm_main.c | 3 +++ > 2 files changed, 14 insertions(+) > > --- linux.orig/include/linux/mm_types.h 2018-12-23 19:58:06.993417137 +0800 > +++ linux/include/linux/mm_types.h 2018-12-23 19:58:06.993417137 +0800 > @@ -27,6 +27,7 @@ typedef int vm_fault_t; > struct address_space; > struct mem_cgroup; > struct hmm; > +struct kvm; > > /* > * Each physical page in the system has a struct page associated with > @@ -496,6 +497,10 @@ struct mm_struct { > /* HMM needs to track a few things per mm */ > struct hmm *hmm; > #endif > + > +#if IS_ENABLED(CONFIG_KVM) > + struct kvm *kvm; > +#endif > } __randomize_layout; > > /* > @@ -507,6 +512,12 @@ struct mm_struct { > > extern struct mm_struct init_mm; > > +#if IS_ENABLED(CONFIG_KVM) > +static inline struct kvm *mm_kvm(struct mm_struct *mm) { return mm->kvm; } > +#else > +static inline struct kvm *mm_kvm(struct mm_struct *mm) { return NULL; } > +#endif > + > /* Pointer magic because the dynamic array size confuses some compilers. */ > static inline void mm_init_cpumask(struct mm_struct *mm) > { > --- linux.orig/virt/kvm/kvm_main.c 2018-12-23 19:58:06.993417137 +0800 > +++ linux/virt/kvm/kvm_main.c 2018-12-23 19:58:06.993417137 +0800 > @@ -727,6 +727,7 @@ static void kvm_destroy_vm(struct kvm *k > struct mm_struct *mm = kvm->mm; > > kvm_uevent_notify_change(KVM_EVENT_DESTROY_VM, kvm); > + mm->kvm = NULL; > kvm_destroy_vm_debugfs(kvm); > kvm_arch_sync_events(kvm); > spin_lock(&kvm_lock); > @@ -3224,6 +3225,8 @@ static int kvm_dev_ioctl_create_vm(unsig > fput(file); > return -ENOMEM; > } > + > + kvm->mm->kvm = kvm; > kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm); > > fd_install(r, file); > > Regards, -- Peter Xu