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 4E0D4C4332F for ; Thu, 28 Apr 2022 12:41:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D7EA86B0088; Thu, 28 Apr 2022 08:41:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CE07C6B0089; Thu, 28 Apr 2022 08:41:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B80C46B008A; Thu, 28 Apr 2022 08:41:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id 9FFC36B0088 for ; Thu, 28 Apr 2022 08:41:33 -0400 (EDT) Received: from smtpin23.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 6475023A6 for ; Thu, 28 Apr 2022 12:41:33 +0000 (UTC) X-FDA: 79406248866.23.4719063 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by imf27.hostedemail.com (Postfix) with ESMTP id C68DC4005C for ; Thu, 28 Apr 2022 12:41:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651149692; x=1682685692; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=jDaoso8XSbsD6Q5i89/pk/Xi3K1DdLaMWFukTg8hKeQ=; b=ml/d73a4ulwRowu6R43m9WFs8GefAXbjaTGLVqE+f36iAZerMLpoOVcp ANGqc9D4HSC6fZvquszxaEx9skFtRk7l9vNFgwl4Zw+hV+bYjQgOTKHiu L1RKsmjQmkLhN78CGhYzUG2ksUQGCZ+tAb6mLVEEz8ucMvZtzLVxfyBWV 7AHQFrFL7Bniw0dYTGY5L3FXTQmkVvFKNxd7F9Fzqvi6l2cHeIHl3kb3z MaKs8Qd6juLqFNIcMQyagWIjIk5F+Q1g0m/35jyu/yJn0LyT9Fk91KXUO z/IxW5L2rTz//K5kKnOP0aCvsB3DdaQjnU1Oc1RMH8ZntOeSD74RLkFbr Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10330"; a="329222173" X-IronPort-AV: E=Sophos;i="5.91,295,1647327600"; d="scan'208";a="329222173" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2022 05:41:30 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,295,1647327600"; d="scan'208";a="706039981" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.192.101]) by fmsmga001.fm.intel.com with ESMTP; 28 Apr 2022 05:41:23 -0700 Date: Thu, 28 Apr 2022 20:37:51 +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 08/13] KVM: Use memfile_pfn_ops to obtain pfn for private pages Message-ID: <20220428123751.GB10508@chaop.bj.intel.com> Reply-To: Chao Peng References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> <20220310140911.50924-9-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C68DC4005C X-Stat-Signature: t9qeuhsxhntgchfra5bdqny7bh8aqebk X-Rspam-User: Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b="ml/d73a4"; spf=none (imf27.hostedemail.com: domain of chao.p.peng@linux.intel.com has no SPF policy when checking 134.134.136.100) smtp.mailfrom=chao.p.peng@linux.intel.com; dmarc=pass (policy=none) header.from=intel.com X-HE-Tag: 1651149690-856534 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 11:56:06PM +0000, Sean Christopherson wrote: > On Thu, Mar 10, 2022, Chao Peng wrote: > > @@ -2217,4 +2220,34 @@ static inline void kvm_handle_signal_exit(struct kvm_vcpu *vcpu) > > /* Max number of entries allowed for each kvm dirty ring */ > > #define KVM_DIRTY_RING_MAX_ENTRIES 65536 > > > > +#ifdef CONFIG_MEMFILE_NOTIFIER > > +static inline long kvm_memfile_get_pfn(struct kvm_memory_slot *slot, gfn_t gfn, > > + int *order) > > +{ > > + pgoff_t index = gfn - slot->base_gfn + > > + (slot->private_offset >> PAGE_SHIFT); > > This is broken for 32-bit kernels, where gfn_t is a 64-bit value but pgoff_t is a > 32-bit value. There's no reason to support this for 32-bit kernels, so... > > The easiest fix, and likely most maintainable for other code too, would be to > add a dedicated CONFIG for private memory, and then have KVM check that for all > the memfile stuff. x86 can then select it only for 64-bit kernels, and in turn > select MEMFILE_NOTIFIER iff private memory is supported. > > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > index ca7b2a6a452a..ee9c8c155300 100644 > --- a/arch/x86/kvm/Kconfig > +++ b/arch/x86/kvm/Kconfig > @@ -48,7 +48,9 @@ config KVM > select SRCU > select INTERVAL_TREE > select HAVE_KVM_PM_NOTIFIER if PM > - select MEMFILE_NOTIFIER > + select HAVE_KVM_PRIVATE_MEM if X86_64 > + select MEMFILE_NOTIFIER if HAVE_KVM_PRIVATE_MEM > + > help > Support hosting fully virtualized guest machines using hardware > virtualization extensions. You will need a fairly recent > > And in addition to replacing checks on CONFIG_MEMFILE_NOTIFIER, the probing of > whether or not KVM_MEM_PRIVATE is allowed can be: > > @@ -1499,23 +1499,19 @@ static void kvm_replace_memslot(struct kvm *kvm, > } > } > > -bool __weak kvm_arch_private_memory_supported(struct kvm *kvm) > -{ > - return false; > -} > - > static int check_memory_region_flags(struct kvm *kvm, > const struct kvm_userspace_memory_region *mem) > { > u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES; > > - if (kvm_arch_private_memory_supported(kvm)) > - valid_flags |= KVM_MEM_PRIVATE; > - > #ifdef __KVM_HAVE_READONLY_MEM > valid_flags |= KVM_MEM_READONLY; > #endif > > +#ifdef CONFIG_KVM_HAVE_PRIVATE_MEM > + valid_flags |= KVM_MEM_PRIVATE; > +#endif One thing to mention is CONFIG_KVM_HAVE_PRIVATE_MEM is build-time thing. Do you think we should or not do that for runtime? E.g. expose by vm_type so only when TDX is enabled KVM_MEM_PRIVATE is exposed. Chao