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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E687DC433EF for ; Thu, 28 Apr 2022 12:41:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346506AbiD1MpB (ORCPT ); Thu, 28 Apr 2022 08:45:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346554AbiD1Mot (ORCPT ); Thu, 28 Apr 2022 08:44:49 -0400 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A36F710FC5; Thu, 28 Apr 2022 05:41:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651149690; x=1682685690; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=jDaoso8XSbsD6Q5i89/pk/Xi3K1DdLaMWFukTg8hKeQ=; b=mTcux2E7ZLul7MpCZLIMfoDriwNJqnMz08/1yY6N7lUQOdpSzQlRi2CR XjwiKL17tL2EoGizi8SGPBxtO5mwy0vXEILR3KOD3OmuKa5T60/aArtms uoKLMaoga72Lyl3+fDW2KsCAjYd7U4rmVIIEHhzAoHIPema68eVdxNhWf +EGhhHkh36orMeUZUh7VvGllZ7CcIkvOj2hY2N+zN10NIGL9Shb2TMz5C ejMydCXr/rM8xB/dmkTC2CprTYklu+G+84dySdNZtXcEj09+ItL2k4VJJ bSSXlAcsEIlKlDltX+qXwtzF5b0WrCyygI6s5wc1q0gCQztlSeeOQk0KC g==; X-IronPort-AV: E=McAfee;i="6400,9594,10330"; a="352710663" X-IronPort-AV: E=Sophos;i="5.91,295,1647327600"; d="scan'208";a="352710663" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga105.fm.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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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