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 47E3AC433EF for ; Fri, 8 Apr 2022 13:47:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A58C96B0074; Fri, 8 Apr 2022 09:47:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A30046B0075; Fri, 8 Apr 2022 09:47:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F7A96B0078; Fri, 8 Apr 2022 09:47:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0050.hostedemail.com [216.40.44.50]) by kanga.kvack.org (Postfix) with ESMTP id 8248C6B0074 for ; Fri, 8 Apr 2022 09:47:03 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 37ADBA89CE for ; Fri, 8 Apr 2022 13:47:03 +0000 (UTC) X-FDA: 79333837926.24.F4C5CF4 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by imf19.hostedemail.com (Postfix) with ESMTP id 186C21A0009 for ; Fri, 8 Apr 2022 13:47:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649425622; x=1680961622; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=Z2KoO20U5Gou3STOQQVbT5tvwIoJoZ5aoHHnzZT/K3Y=; b=XyU8otFMWgj81vvB2b7xY0OcmVYv+aWFeSFSzcE9M5cF8k8wLaNhl79j uyXpiTyHXjBFhYxCBPtzY0GIvjdKXYVXXKNZI9R3AVPjAhBBP2B68Uagx uwGELtiA9QTDICiG+tVeyim4gSXQni61foL98mRVUAYvigTbBu0tV+MMx +gH/R/j+By27MIchy78uImEhzCWeFuGY7Kh2SrFiJLKRvutPDAi0EVfee 0GXRidNFTSZ3fZASJt5ER9NObf+ErZFCULXgP8g6QIB3QcLl24Vr6Wo4V NykkFpB1HIMUKCAlES5Ejz7TAPZYn3ycJemF/w7b1cxk/eAnRRBFmL7Ws A==; X-IronPort-AV: E=McAfee;i="6400,9594,10310"; a="243728237" X-IronPort-AV: E=Sophos;i="5.90,245,1643702400"; d="scan'208";a="243728237" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Apr 2022 06:47:00 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,245,1643702400"; d="scan'208";a="698187600" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.192.101]) by fmsmga001.fm.intel.com with ESMTP; 08 Apr 2022 06:46:52 -0700 Date: Fri, 8 Apr 2022 21:46:41 +0800 From: Chao Peng To: Sean Christopherson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , 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 , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com Subject: Re: [PATCH v5 05/13] KVM: Extend the memslot to support fd-based private memory Message-ID: <20220408134641.GD57095@chaop.bj.intel.com> Reply-To: Chao Peng References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> <20220310140911.50924-6-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=XyU8otFM; spf=none (imf19.hostedemail.com: domain of chao.p.peng@linux.intel.com has no SPF policy when checking 134.134.136.126) smtp.mailfrom=chao.p.peng@linux.intel.com; dmarc=pass (policy=none) header.from=intel.com X-Stat-Signature: botbhnohq4wbr189hcrxudmxfgux3yh8 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 186C21A0009 X-HE-Tag: 1649425621-743227 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 Mon, Mar 28, 2022 at 09:56:33PM +0000, Sean Christopherson wrote: > On Thu, Mar 10, 2022, Chao Peng wrote: > > Extend the memslot definition to provide fd-based private memory support > > by adding two new fields (private_fd/private_offset). The memslot then > > can maintain memory for both shared pages and private pages in a single > > memslot. Shared pages are provided by existing userspace_addr(hva) field > > and private pages are provided through the new private_fd/private_offset > > fields. > > > > Since there is no 'hva' concept anymore for private memory so we cannot > > rely on get_user_pages() to get a pfn, instead we use the newly added > > memfile_notifier to complete the same job. > > > > This new extension is indicated by a new flag KVM_MEM_PRIVATE. > > > > Signed-off-by: Yu Zhang > > Signed-off-by: Chao Peng > > --- > > Documentation/virt/kvm/api.rst | 37 +++++++++++++++++++++++++++------- > > include/linux/kvm_host.h | 7 +++++++ > > include/uapi/linux/kvm.h | 8 ++++++++ > > 3 files changed, 45 insertions(+), 7 deletions(-) > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > index 3acbf4d263a5..f76ac598606c 100644 > > --- a/Documentation/virt/kvm/api.rst > > +++ b/Documentation/virt/kvm/api.rst > > @@ -1307,7 +1307,7 @@ yet and must be cleared on entry. > > :Capability: KVM_CAP_USER_MEMORY > > :Architectures: all > > :Type: vm ioctl > > -:Parameters: struct kvm_userspace_memory_region (in) > > +:Parameters: struct kvm_userspace_memory_region(_ext) (in) > > :Returns: 0 on success, -1 on error > > > > :: > > @@ -1320,9 +1320,17 @@ yet and must be cleared on entry. > > __u64 userspace_addr; /* start of the userspace allocated memory */ > > }; > > > > + struct kvm_userspace_memory_region_ext { > > + struct kvm_userspace_memory_region region; > > Peeking ahead, the partial switch to the _ext variant is rather gross. I would > prefer that KVM use an entirely different, but binary compatible, struct internally. > And once the kernel supports C11[*], I'm pretty sure we can make the "region" in > _ext an anonymous struct, and make KVM's internal struct a #define of _ext. That > should minimize the churn (no need to get the embedded "region" field), reduce > line lengths, and avoid confusion due to some flows taking the _ext but others > dealing with only the "base" struct. Will try that. > > Maybe kvm_user_memory_region or kvm_user_mem_region? Though it's tempting to be > evil and usurp the old kvm_memory_region :-) > > E.g. pre-C11 do > > struct kvm_userspace_memory_region_ext { > struct kvm_userspace_memory_region region; > __u64 private_offset; > __u32 private_fd; > __u32 padding[5]; > }; > > #ifdef __KERNEL__ > struct kvm_user_mem_region { > __u32 slot; > __u32 flags; > __u64 guest_phys_addr; > __u64 memory_size; /* bytes */ > __u64 userspace_addr; /* start of the userspace allocated memory */ > __u64 private_offset; > __u32 private_fd; > __u32 padding[5]; > }; > #endif > > and then post-C11 do > > struct kvm_userspace_memory_region_ext { > #ifdef __KERNEL__ Is this #ifndef? As I think anonymous struct is only for kernel? Thanks, Chao > struct kvm_userspace_memory_region region; > #else > struct kvm_userspace_memory_region; > #endif > __u64 private_offset; > __u32 private_fd; > __u32 padding[5]; > }; > > #ifdef __KERNEL__ > #define kvm_user_mem_region kvm_userspace_memory_region_ext > #endif > > [*] https://lore.kernel.org/all/20220301145233.3689119-1-arnd@kernel.org > > > + __u64 private_offset; > > + __u32 private_fd; > > + __u32 padding[5]; > > +};