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 9679EC433FE for ; Wed, 26 Oct 2022 20:46:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234599AbiJZUq2 (ORCPT ); Wed, 26 Oct 2022 16:46:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234241AbiJZUqY (ORCPT ); Wed, 26 Oct 2022 16:46:24 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 04ED2792F4; Wed, 26 Oct 2022 13:46:23 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id u8-20020a17090a5e4800b002106dcdd4a0so3976145pji.1; Wed, 26 Oct 2022 13:46:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=osbqX8leV6g/SkiEHlFgEuxy7LRzWU2Y7Uh+l7tX15w=; b=jpYjPBLG06J9WOn/bBWpwBCbAYRsRYqGtpSJMTFmnFYTA2ZFnazgRXI8p//toCQ2TJ y0spJgx5cSlhzZ3SljvtDIADHdIjucdfN8NSuX9QNmLHoPzorq79XbjryWXjfHFl30lq a+yGNHUmONi8/9fjz20oKzw3ydyHBmBZfyBBhDMaJiuRleHwSAzhKieuIBUJl+OaRWkx J8ePiRgrp1obhqOjSj/zBR/mn+zZs1yFys+iRMsX91dPwar3019jAkA21DzvD4AEs3Ci EqQhVJdb++3PMZsV4Ve+oth/VTO9h3hSFBdHXErMhMsb9uXlU65Dc3fy+9wGFc3kxwVE 7xyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=osbqX8leV6g/SkiEHlFgEuxy7LRzWU2Y7Uh+l7tX15w=; b=pWmAG25EI2ueXl0IeDbrrmorANO51zg96TsFc9GR9OutZa1SD+xCY0aiXmSYs+KU3s y5tDb4/IHsUcOdKEhIsKqDmj1Ifj66lYr0E8M9+fKX7sXhV8LYV9kJFQKCQ5SDgyacO4 HUm4KWW9Z1dg0axMoJWVpVhr3d0R7gdaRSTj/VVh/kFU7Z8g1m6Pjjsqb1REAtFgB6Ng nkgLO1Fz6w1JjWypm7K4Pe3oizY3otijOI4D/Gw2dvVnt8/R4/4tnn9rDLSdBCbaJO34 DZbE7t2DO0CLDVSBk1+tFw5eU3KHCHowrWnY+NSdpipC8HxqHU3rEakdZBBQq2490C5f whxg== X-Gm-Message-State: ACrzQf0DqPeWIXYkG2Zift1zj+gIF4S7nUEcWUKObQKS860e5uRKzLqC +4lB2rLiD/7q4bcHvhDZg9o= X-Google-Smtp-Source: AMsMyM7NaRTKclIWYEWcxpgdPdqgRZFy22OSD7N8p45NptTu2RyVSV2oujVK1I0Ov2AG9q7XgNRCoQ== X-Received: by 2002:a17:902:7b95:b0:178:ab50:76b5 with SMTP id w21-20020a1709027b9500b00178ab5076b5mr46490591pll.161.1666817182250; Wed, 26 Oct 2022 13:46:22 -0700 (PDT) Received: from localhost ([192.55.54.55]) by smtp.gmail.com with ESMTPSA id a8-20020a170902710800b00172973d3cd9sm3308650pll.55.2022.10.26.13.46.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Oct 2022 13:46:21 -0700 (PDT) Date: Wed, 26 Oct 2022 13:46:20 -0700 From: Isaku Yamahata To: Chao Peng 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, isaku.yamahata@gmail.com Subject: Re: [PATCH v9 6/8] KVM: Update lpage info when private/shared memory are mixed Message-ID: <20221026204620.GB3819453@ls.amr.corp.intel.com> References: <20221025151344.3784230-1-chao.p.peng@linux.intel.com> <20221025151344.3784230-7-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20221025151344.3784230-7-chao.p.peng@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > + } > + > + 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. > + 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