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 2B0CCC433EF for ; Tue, 12 Apr 2022 12:43:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 835436B0082; Tue, 12 Apr 2022 08:43:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7E3246B0083; Tue, 12 Apr 2022 08:43:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6AB1D6B0085; Tue, 12 Apr 2022 08:43:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0152.hostedemail.com [216.40.44.152]) by kanga.kvack.org (Postfix) with ESMTP id 5BD966B0082 for ; Tue, 12 Apr 2022 08:43:47 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 1C89D183A38BF for ; Tue, 12 Apr 2022 12:43:47 +0000 (UTC) X-FDA: 79348193694.23.A9C57E1 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by imf08.hostedemail.com (Postfix) with ESMTP id 1AF9D160007 for ; Tue, 12 Apr 2022 12:43:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649767426; x=1681303426; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=dy/TdJnUMbUKhIlocJ/LouJFjjtZwg5GwrTeZmhomcI=; b=ny63gkEjCaQBzP0sr4UqGE19F1FlJZWRGCdZpd8B26RKme6kMT61fcu5 hD1Bu/iL1uxC8TlzJbJ6y12lLsUgfkeqZLXkVXMhVhZ+iUAZySDM7TAKv MfWTaBvvhBk2V6MKtMw1Kqu1afG0p+2buv3KqT9XASJn4BRBfbCDvwT/H pNNu7TqfOVGMz0KZXQsz8nmLc72OjdbGoakRwCkcZT0qsXAub69zuGykP n1HnCh5WFGrDwOZI7h3p9kK7k24oVpeFSRj/tHMQUkNRmeeQxGVgDD+7o li2LZl5xJH8YmRKmhuLmLfQ9bw+O0GqZNRSpzUDDkVyvtcsiMnYoZwBuB Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10314"; a="249648907" X-IronPort-AV: E=Sophos;i="5.90,253,1643702400"; d="scan'208";a="249648907" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Apr 2022 05:43:44 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,253,1643702400"; d="scan'208";a="526024498" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.192.101]) by orsmga002.jf.intel.com with ESMTP; 12 Apr 2022 05:43:36 -0700 Date: Tue, 12 Apr 2022 20:43:25 +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 11/13] KVM: Zap existing KVM mappings when pages changed in the private fd Message-ID: <20220412124325.GB8013@chaop.bj.intel.com> Reply-To: Chao Peng References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> <20220310140911.50924-12-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) X-Stat-Signature: k6ds3uxjjys19j4i5t5jzmn6ee3kwccg Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=intel.com header.s=Intel header.b=ny63gkEj; spf=none (imf08.hostedemail.com: domain of chao.p.peng@linux.intel.com has no SPF policy when checking 134.134.136.20) smtp.mailfrom=chao.p.peng@linux.intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1AF9D160007 X-HE-Tag: 1649767425-712613 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 Tue, Mar 29, 2022 at 07:23:04PM +0000, Sean Christopherson wrote: > On Thu, Mar 10, 2022, Chao Peng wrote: > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index 67349421eae3..52319f49d58a 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -841,8 +841,43 @@ static int kvm_init_mmu_notifier(struct kvm *kvm) > > #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */ > > > > #ifdef CONFIG_MEMFILE_NOTIFIER > > +static void kvm_memfile_notifier_handler(struct memfile_notifier *notifier, > > + pgoff_t start, pgoff_t end) > > +{ > > + int idx; > > + struct kvm_memory_slot *slot = container_of(notifier, > > + struct kvm_memory_slot, > > + notifier); > > + struct kvm_gfn_range gfn_range = { > > + .slot = slot, > > + .start = start - (slot->private_offset >> PAGE_SHIFT), > > + .end = end - (slot->private_offset >> PAGE_SHIFT), > > + .may_block = true, > > + }; > > + struct kvm *kvm = slot->kvm; > > + > > + gfn_range.start = max(gfn_range.start, slot->base_gfn); > > + gfn_range.end = min(gfn_range.end, slot->base_gfn + slot->npages); > > + > > + if (gfn_range.start >= gfn_range.end) > > + return; > > + > > + idx = srcu_read_lock(&kvm->srcu); > > + KVM_MMU_LOCK(kvm); > > + kvm_unmap_gfn_range(kvm, &gfn_range); > > + kvm_flush_remote_tlbs(kvm); > > This should check the result of kvm_unmap_gfn_range() and flush only if necessary. Yep. > > kvm->mmu_notifier_seq needs to be incremented, otherwise KVM will incorrectly > install a SPTE if the mapping is zapped between retrieving the pfn in faultin and > installing it after acquire mmu_lock. Good catch. Chao > > > > + KVM_MMU_UNLOCK(kvm); > > + srcu_read_unlock(&kvm->srcu, idx); > > +} > > + > > +static struct memfile_notifier_ops kvm_memfile_notifier_ops = { > > + .invalidate = kvm_memfile_notifier_handler, > > + .fallocate = kvm_memfile_notifier_handler, > > +}; > > + > > static inline int kvm_memfile_register(struct kvm_memory_slot *slot) > > { > > + slot->notifier.ops = &kvm_memfile_notifier_ops; > > return memfile_register_notifier(file_inode(slot->private_file), > > &slot->notifier, > > &slot->pfn_ops); > > @@ -1963,6 +1998,7 @@ int __kvm_set_memory_region(struct kvm *kvm, > > new->private_file = file; > > new->private_offset = mem->flags & KVM_MEM_PRIVATE ? > > region_ext->private_offset : 0; > > + new->kvm = kvm; > > > > r = kvm_set_memslot(kvm, old, new, change); > > if (!r) > > -- > > 2.17.1 > >