From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFE8DC433F5 for ; Thu, 25 Nov 2021 16:56:25 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 01BF06B0074; Thu, 25 Nov 2021 11:56:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id F0CD96B0075; Thu, 25 Nov 2021 11:56:09 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DD41D6B0078; Thu, 25 Nov 2021 11:56:09 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0125.hostedemail.com [216.40.44.125]) by kanga.kvack.org (Postfix) with ESMTP id D047E6B0074 for ; Thu, 25 Nov 2021 11:56:09 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 9745382C7E57 for ; Thu, 25 Nov 2021 16:55:59 +0000 (UTC) X-FDA: 78848054838.30.844D7CA Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf29.hostedemail.com (Postfix) with ESMTP id EEB63900066C for ; Thu, 25 Nov 2021 16:55:55 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 065761042; Thu, 25 Nov 2021 08:55:58 -0800 (PST) Received: from [10.57.29.213] (unknown [10.57.29.213]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1C75C3F73B; Thu, 25 Nov 2021 08:55:53 -0800 (PST) Subject: Re: [RFC v2 PATCH 06/13] KVM: Register/unregister memfd backed memslot To: Chao Peng , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, qemu-devel@nongnu.org Cc: Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, john.ji@intel.com, susie.li@intel.com, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com References: <20211119134739.20218-1-chao.p.peng@linux.intel.com> <20211119134739.20218-7-chao.p.peng@linux.intel.com> From: Steven Price Message-ID: Date: Thu, 25 Nov 2021 16:55:52 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211119134739.20218-7-chao.p.peng@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: EEB63900066C X-Stat-Signature: q9oiew5c396bu9x8ddxgwoqqhxgcxedr Authentication-Results: imf29.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf29.hostedemail.com: domain of steven.price@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=steven.price@arm.com X-HE-Tag: 1637859355-75038 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 19/11/2021 13:47, Chao Peng wrote: > Signed-off-by: Yu Zhang > Signed-off-by: Chao Peng > --- > virt/kvm/kvm_main.c | 23 +++++++++++++++++++---- > 1 file changed, 19 insertions(+), 4 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 271cef8d1cd0..b8673490d301 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1426,7 +1426,7 @@ static void update_memslots(struct kvm_memslots *slots, > static int check_memory_region_flags(struct kvm *kvm, > const struct kvm_userspace_memory_region_ext *mem) > { > - u32 valid_flags = 0; > + u32 valid_flags = KVM_MEM_FD; > > if (!kvm->dirty_log_unsupported) > valid_flags |= KVM_MEM_LOG_DIRTY_PAGES; > @@ -1604,10 +1604,20 @@ static int kvm_set_memslot(struct kvm *kvm, > kvm_copy_memslots(slots, __kvm_memslots(kvm, as_id)); > } > > + if (mem->flags & KVM_MEM_FD && change == KVM_MR_CREATE) { > + r = kvm_memfd_register(kvm, mem, new); > + if (r) > + goto out_slots; > + } > + > r = kvm_arch_prepare_memory_region(kvm, new, mem, change); > if (r) > goto out_slots; > > + if (mem->flags & KVM_MEM_FD && (r || change == KVM_MR_DELETE)) { ^ r will never be non-zero as the 'if' above will catch that case and jump to out_slots. I *think* the intention was that the "if (r)" code should be after this check to clean up in the case of error from kvm_arch_prepare_memory_region() (as well as an explicit MR_DELETE). Steve > + kvm_memfd_unregister(kvm, new); > + } > + > update_memslots(slots, new, change); > slots = install_new_memslots(kvm, as_id, slots); > > @@ -1683,10 +1693,12 @@ int __kvm_set_memory_region(struct kvm *kvm, > return -EINVAL; > if (mem->guest_phys_addr & (PAGE_SIZE - 1)) > return -EINVAL; > - /* We can read the guest memory with __xxx_user() later on. */ > if ((mem->userspace_addr & (PAGE_SIZE - 1)) || > - (mem->userspace_addr != untagged_addr(mem->userspace_addr)) || > - !access_ok((void __user *)(unsigned long)mem->userspace_addr, > + (mem->userspace_addr != untagged_addr(mem->userspace_addr))) > + return -EINVAL; > + /* We can read the guest memory with __xxx_user() later on. */ > + if (!(mem->flags & KVM_MEM_FD) && > + !access_ok((void __user *)(unsigned long)mem->userspace_addr, > mem->memory_size)) > return -EINVAL; > if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM) > @@ -1727,6 +1739,9 @@ int __kvm_set_memory_region(struct kvm *kvm, > new.dirty_bitmap = NULL; > memset(&new.arch, 0, sizeof(new.arch)); > } else { /* Modify an existing slot. */ > + /* Private memslots are immutable, they can only be deleted. */ > + if (mem->flags & KVM_MEM_FD && mem->private_fd >= 0) > + return -EINVAL; > if ((new.userspace_addr != old.userspace_addr) || > (new.npages != old.npages) || > ((new.flags ^ old.flags) & KVM_MEM_READONLY)) >