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 07F6AC433FE for ; Tue, 8 Nov 2022 12:08:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 893938E0001; Tue, 8 Nov 2022 07:08:20 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 842F96B0073; Tue, 8 Nov 2022 07:08:20 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 70B288E0001; Tue, 8 Nov 2022 07:08:20 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 616B56B0071 for ; Tue, 8 Nov 2022 07:08:20 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 2B6931A0778 for ; Tue, 8 Nov 2022 12:08:20 +0000 (UTC) X-FDA: 80110152360.12.1BD3D68 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by imf30.hostedemail.com (Postfix) with ESMTP id 2285780004 for ; Tue, 8 Nov 2022 12:08:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1667909299; x=1699445299; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=caRUr7sQcj7Z1erPIwFwOEGdgx5trQeO2xkwYKL7cBE=; b=FYQGZnHSBL35heYKpAdWT/H7vsw0f5hPvhi1QCMfYydcT1Xx/h9IQfHE uIru6oOrmJkqFekUjS72JUIZt5G87arFS1oqWFing+pj93IsU+rDkOQIF tBCaxlqC2nOcKkE2pUulNfpiNxiX25JpUOS/MujFsan0CSsIa1e3doIy9 tW13t1KOUDdVR0WkjDh8orKvXU2vvfbB2+U9Az9YC57oft3rBMHAY2iy6 rTcVG1LoJJF5uSlWHot3+Y9k0SmmNAeNUSg3DRZRGIQ28qA7JhNZa9OxO LVyjlkJ/6TE7WQW3+ukdjfsCng4k5+aeKMg3JO9zikw4qVYd+RRQR7F17 g==; X-IronPort-AV: E=McAfee;i="6500,9779,10524"; a="311832708" X-IronPort-AV: E=Sophos;i="5.96,147,1665471600"; d="scan'208";a="311832708" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Nov 2022 04:08:17 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10524"; a="667566067" X-IronPort-AV: E=Sophos;i="5.96,147,1665471600"; d="scan'208";a="667566067" Received: from yy-desk-7060.sh.intel.com (HELO localhost) ([10.239.159.76]) by orsmga008.jf.intel.com with ESMTP; 08 Nov 2022 04:08:06 -0800 Date: Tue, 8 Nov 2022 20:08:05 +0800 From: Yuan Yao 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 Subject: Re: [PATCH v9 6/8] KVM: Update lpage info when private/shared memory are mixed Message-ID: <20221108120805.kize74qgzsmarze5@yy-desk-7060> 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=us-ascii Content-Disposition: inline In-Reply-To: <20221025151344.3784230-7-chao.p.peng@linux.intel.com> User-Agent: NeoMutt/20171215 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1667909299; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ygqwneSn08pOP7q4gwyJTtwPRQpGz+532FZqd4VbSaQ=; b=GV4QT11xylZLtvW702pDofFFKctenH4JbpDqO3Ahja/sCA4JKzdnjV33hyWR1FbflQho5Z 32es1Daa87lc6gFc9Nb+4JxBwMyEBRp4exeimxem8LJaL24NWReUIycBy67gJ0h7sPsKs0 B+VZz1O1pfhg4NwqU4MgmReu0doMl2o= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=FYQGZnHS; spf=none (imf30.hostedemail.com: domain of yuan.yao@linux.intel.com has no SPF policy when checking 134.134.136.24) smtp.mailfrom=yuan.yao@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1667909299; a=rsa-sha256; cv=none; b=XnruzBQ86w2JfQ81sdCjpU6KKm9dAPSfbV4GJ2OWJo2t5b1S9T6GH6Fi8j25Y6eM88dvNG IufiTEkSJ9nNZfWwlc14kbUTcW5Jqnnv46gh8djzawZfk431T6zI6sBlBFoW/h3qblB8lF OhycY72Ro3GzdbJv8vCu78mgn63RpSE= X-Rspam-User: X-Stat-Signature: rnwfpcuhqyu1u6fx3yn31g7mnydmz8g6 X-Rspamd-Queue-Id: 2285780004 Authentication-Results: imf30.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=FYQGZnHS; spf=none (imf30.hostedemail.com: domain of yuan.yao@linux.intel.com has no SPF policy when checking 134.134.136.24) smtp.mailfrom=yuan.yao@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) X-Rspamd-Server: rspam07 X-HE-Tag: 1667909298-639557 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, 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/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 7551b6f9c31c..db811a54e3fd 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -37,6 +37,7 @@ > #include > > #define __KVM_HAVE_ARCH_VCPU_DEBUGFS > +#define __KVM_HAVE_ARCH_UPDATE_MEM_ATTR > > #define KVM_MAX_VCPUS 1024 > > @@ -952,6 +953,13 @@ struct kvm_vcpu_arch { > #endif > }; > > +/* > + * Use a bit in disallow_lpage to indicate private/shared pages mixed at the > + * level. The remaining bits are used as a reference count. > + */ > +#define KVM_LPAGE_PRIVATE_SHARED_MIXED (1U << 31) > +#define KVM_LPAGE_COUNT_MAX ((1U << 31) - 1) > + > struct kvm_lpage_info { > int disallow_lpage; > }; > 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 > @@ -762,11 +762,16 @@ static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot, > { > struct kvm_lpage_info *linfo; > int i; > + int disallow_count; > > for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { > linfo = lpage_info_slot(gfn, slot, i); > + > + disallow_count = linfo->disallow_lpage & KVM_LPAGE_COUNT_MAX; > + WARN_ON(disallow_count + count < 0 || > + disallow_count > KVM_LPAGE_COUNT_MAX - count); > + > linfo->disallow_lpage += count; > - WARN_ON(linfo->disallow_lpage < 0); > } > } > > @@ -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; > + } > + > + 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); > + 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)); Looks only query the lpage_start, start is not enough: A and B are private gfns from same lpage_start as below, A > B : lpage_start |---------A |----B Convert A to shared, this makes the upper 2M page to MIX. Convert B to shared, this also makes the upper 2M page to MIX. Convert B to private, this makes the upper 2M page to Non-MIX, but it's incorrect, due to A is shared. Same to tail case. > + > + 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)); > + } > +} > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 02ad31f46dd7..4276ca73bd7b 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -12563,6 +12563,8 @@ static int kvm_alloc_memslot_metadata(struct kvm *kvm, > if ((slot->base_gfn + npages) & (KVM_PAGES_PER_HPAGE(level) - 1)) > linfo[lpages - 1].disallow_lpage = 1; > ugfn = slot->userspace_addr >> PAGE_SHIFT; > + if (kvm_slot_can_be_private(slot)) > + ugfn |= slot->restricted_offset >> PAGE_SHIFT; > /* > * If the gfn and userspace address are not aligned wrt each > * other, disable large page support for this slot. > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 4ce98fa0153c..6ce36065532c 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -2284,4 +2284,23 @@ static inline void kvm_account_pgtable_pages(void *virt, int nr) > /* Max number of entries allowed for each kvm dirty ring */ > #define KVM_DIRTY_RING_MAX_ENTRIES 65536 > > +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM > + > +#define KVM_MEM_ATTR_SHARED 0x0001 > +#define KVM_MEM_ATTR_PRIVATE 0x0002 > + > +#ifdef __KVM_HAVE_ARCH_UPDATE_MEM_ATTR > +void kvm_arch_update_mem_attr(struct kvm *kvm, struct kvm_memory_slot *slot, > + unsigned int attr, gfn_t start, gfn_t end); > +#else > +static inline void kvm_arch_update_mem_attr(struct kvm *kvm, > + struct kvm_memory_slot *slot, > + unsigned int attr, > + gfn_t start, gfn_t end) > +{ > +} > +#endif > + > +#endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM */ > + > #endif > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index fc3835826ace..13a37b4d9e97 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -939,7 +939,8 @@ static int kvm_init_mmu_notifier(struct kvm *kvm) > > #ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM > > -static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > +static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end, > + unsigned int attr) > { > struct kvm_gfn_range gfn_range; > struct kvm_memory_slot *slot; > @@ -963,6 +964,7 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > gfn_range.slot = slot; > > r |= kvm_unmap_gfn_range(kvm, &gfn_range); > + kvm_arch_update_mem_attr(kvm, slot, attr, start, end); > } > } > > @@ -970,7 +972,6 @@ static void kvm_unmap_mem_range(struct kvm *kvm, gfn_t start, gfn_t end) > kvm_flush_remote_tlbs(kvm); > } > > -#define KVM_MEM_ATTR_SHARED 0x0001 > static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > bool is_private) > { > @@ -979,6 +980,7 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > void *entry; > int idx; > int r = 0; > + unsigned int attr; > > if (size == 0 || gpa + size < gpa) > return -EINVAL; > @@ -992,7 +994,13 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > * Guest memory defaults to private, kvm->mem_attr_array only stores > * shared memory. > */ > - entry = is_private ? NULL : xa_mk_value(KVM_MEM_ATTR_SHARED); > + if (is_private) { > + attr = KVM_MEM_ATTR_PRIVATE; > + entry = NULL; > + } else { > + attr = KVM_MEM_ATTR_SHARED; > + entry = xa_mk_value(KVM_MEM_ATTR_SHARED); > + } > > idx = srcu_read_lock(&kvm->srcu); > KVM_MMU_LOCK(kvm); > @@ -1005,7 +1013,7 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size, > goto err; > } > > - kvm_unmap_mem_range(kvm, start, end); > + kvm_unmap_mem_range(kvm, start, end, attr); > > goto ret; > err: > -- > 2.25.1 >