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 8604AECAAA1 for ; Fri, 28 Oct 2022 06:47:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230157AbiJ1Grh (ORCPT ); Fri, 28 Oct 2022 02:47:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229980AbiJ1Gq7 (ORCPT ); Fri, 28 Oct 2022 02:46:59 -0400 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD5C715B31E; Thu, 27 Oct 2022 23:43:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1666939405; x=1698475405; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=8NnFR5a6Ov4GS57k7NcQ6r9rc2t1vYt8WPecZyaK0cQ=; b=M+doX1X/NFa5YSyRRXs1GZCSJZgsZ7wRChFO2Wylvx1ZDECW8psDEKLo O80rwYAz2VcqybEVJLerEvRl8uP0BGQmSwDLXjBv+fVtrhMyDt8aO//t3 g8WkHSSMdFqpKeaLXsZAN8BfBqcM54CYNIoUMOTAVfvkCh9o8wBTnC3jm erdq6vBr4NK4XMhU+vF2ysjKYuqv2QN5eDUCG9m7Y4vOkZTWlulKqkmAp 2/285QTJaeePNQgXoiOzqmGbzcilgCaV3VYcyRJ8lw4nwykwS9LXqN1kh YwK/0BqgaibJFKRzkFmYbzjZO0PfzM0eKuofnOIHj0chH2XwLWjtt0OXQ A==; X-IronPort-AV: E=McAfee;i="6500,9779,10513"; a="288139755" X-IronPort-AV: E=Sophos;i="5.95,220,1661842800"; d="scan'208";a="288139755" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Oct 2022 23:43:05 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10513"; a="696111933" X-IronPort-AV: E=Sophos;i="5.95,220,1661842800"; d="scan'208";a="696111933" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.75]) by fmsmga008.fm.intel.com with ESMTP; 27 Oct 2022 23:42:55 -0700 Date: Fri, 28 Oct 2022 14:38:26 +0800 From: Chao Peng To: Isaku Yamahata Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, 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 , Shuah Khan , 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, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , tabba@google.com, Michael Roth , mhocko@suse.com, Muchun Song , wei.w.wang@intel.com Subject: Re: [PATCH v9 6/8] KVM: Update lpage info when private/shared memory are mixed Message-ID: <20221028063826.GC3885130@chaop.bj.intel.com> Reply-To: Chao Peng References: <20221025151344.3784230-1-chao.p.peng@linux.intel.com> <20221025151344.3784230-7-chao.p.peng@linux.intel.com> <20221026204620.GB3819453@ls.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221026204620.GB3819453@ls.amr.corp.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 26, 2022 at 01:46:20PM -0700, Isaku Yamahata wrote: > On Tue, Oct 25, 2022 at 11:13:42PM +0800, > Chao Peng wrote: > > > When private/shared memory are mixed in a large page, the lpage_info may > > not be accurate and should be updated with this mixed info. A large page > > has mixed pages can't be really mapped as large page since its > > private/shared pages are from different physical memory. > > > > Update lpage_info when private/shared memory attribute is changed. If > > both private and shared pages are within a large page region, it can't > > be mapped as large page. It's a bit challenge to track the mixed > > info in a 'count' like variable, this patch instead reserves a bit in > > 'disallow_lpage' to indicate a large page has mixed private/share pages. > > > > Signed-off-by: Chao Peng > > --- > > arch/x86/include/asm/kvm_host.h | 8 +++ > > arch/x86/kvm/mmu/mmu.c | 112 +++++++++++++++++++++++++++++++- > > arch/x86/kvm/x86.c | 2 + > > include/linux/kvm_host.h | 19 ++++++ > > virt/kvm/kvm_main.c | 16 +++-- > > 5 files changed, 152 insertions(+), 5 deletions(-) > > > ... > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > > index 33b1aec44fb8..67a9823a8c35 100644 > > --- a/arch/x86/kvm/mmu/mmu.c > > +++ b/arch/x86/kvm/mmu/mmu.c > ... > > @@ -6910,3 +6915,108 @@ void kvm_mmu_pre_destroy_vm(struct kvm *kvm) > > if (kvm->arch.nx_lpage_recovery_thread) > > kthread_stop(kvm->arch.nx_lpage_recovery_thread); > > } > > + > > +static inline bool linfo_is_mixed(struct kvm_lpage_info *linfo) > > +{ > > + return linfo->disallow_lpage & KVM_LPAGE_PRIVATE_SHARED_MIXED; > > +} > > + > > +static inline void linfo_update_mixed(struct kvm_lpage_info *linfo, bool mixed) > > +{ > > + if (mixed) > > + linfo->disallow_lpage |= KVM_LPAGE_PRIVATE_SHARED_MIXED; > > + else > > + linfo->disallow_lpage &= ~KVM_LPAGE_PRIVATE_SHARED_MIXED; > > +} > > + > > +static bool mem_attr_is_mixed_2m(struct kvm *kvm, unsigned int attr, > > + gfn_t start, gfn_t end) > > +{ > > + XA_STATE(xas, &kvm->mem_attr_array, start); > > + gfn_t gfn = start; > > + void *entry; > > + bool shared = attr == KVM_MEM_ATTR_SHARED; > > + bool mixed = false; > > + > > + rcu_read_lock(); > > + entry = xas_load(&xas); > > + while (gfn < end) { > > + if (xas_retry(&xas, entry)) > > + continue; > > + > > + KVM_BUG_ON(gfn != xas.xa_index, kvm); > > + > > + if ((entry && !shared) || (!entry && shared)) { > > + mixed = true; > > + goto out; > > nitpick: goto isn't needed. break should work. Thanks. > > > + } > > + > > + entry = xas_next(&xas); > > + gfn++; > > + } > > +out: > > + rcu_read_unlock(); > > + return mixed; > > +} > > + > > +static bool mem_attr_is_mixed(struct kvm *kvm, struct kvm_memory_slot *slot, > > + int level, unsigned int attr, > > + gfn_t start, gfn_t end) > > +{ > > + unsigned long gfn; > > + void *entry; > > + > > + if (level == PG_LEVEL_2M) > > + return mem_attr_is_mixed_2m(kvm, attr, start, end); > > + > > + entry = xa_load(&kvm->mem_attr_array, start); > > + for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) { > > + if (linfo_is_mixed(lpage_info_slot(gfn, slot, level - 1))) > > + return true; > > + if (xa_load(&kvm->mem_attr_array, gfn) != entry) > > + return true; > > + } > > + return false; > > +} > > + > > +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, > > + unsigned int attr, gfn_t start, gfn_t end) > > +{ > > + > > + unsigned long lpage_start, lpage_end; > > + unsigned long gfn, pages, mask; > > + int level; > > + > > + WARN_ONCE(!(attr & (KVM_MEM_ATTR_PRIVATE | KVM_MEM_ATTR_SHARED)), > > + "Unsupported mem attribute.\n"); > > + > > + /* > > + * The sequence matters here: we update the higher level basing on the > > + * lower level's scanning result. > > + */ > > + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { > > + pages = KVM_PAGES_PER_HPAGE(level); > > + mask = ~(pages - 1); > > nitpick: KVM_HPAGE_MASK(level). Maybe matter of preference. Yes, haven't noticed there is a KVM_HPAGE_MASK defined. Have no strong preference here, since I already have KVM_PAGES_PER_HPAGE(level), getting mask is straightforward. A single KVM_HPAGE_MASK(level) will not give me what I need since here is gfn, KVM_HPAGE_MASK(level)>> PAGE_SHIFT should be the right equivalent. Chao > > > > + lpage_start = max(start & mask, slot->base_gfn); > > + lpage_end = (end - 1) & mask; > > + > > + /* > > + * We only need to scan the head and tail page, for middle pages > > + * we know they are not mixed. > > + */ > > + linfo_update_mixed(lpage_info_slot(lpage_start, slot, level), > > + mem_attr_is_mixed(kvm, slot, level, attr, > > + lpage_start, start)); > > + > > + if (lpage_start == lpage_end) > > + return; > > + > > + for (gfn = lpage_start + pages; gfn < lpage_end; gfn += pages) > > + linfo_update_mixed(lpage_info_slot(gfn, slot, level), > > + false); > > + > > + linfo_update_mixed(lpage_info_slot(lpage_end, slot, level), > > + mem_attr_is_mixed(kvm, slot, level, attr, > > + end, lpage_end + pages)); > > + } > > +} > > -- > Isaku Yamahata