From patchwork Thu Sep 5 10:29:16 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xiao Guangrong X-Patchwork-Id: 2854028 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A3047C0AB5 for ; Thu, 5 Sep 2013 10:31:03 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5EB4D2028F for ; Thu, 5 Sep 2013 10:31:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D32ED20206 for ; Thu, 5 Sep 2013 10:31:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965271Ab3IEKa4 (ORCPT ); Thu, 5 Sep 2013 06:30:56 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:58592 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935732Ab3IEK3t (ORCPT ); Thu, 5 Sep 2013 06:29:49 -0400 Received: from /spool/local by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Thu, 5 Sep 2013 20:15:47 +1000 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [9.190.235.21]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 29DB32CE804D; Thu, 5 Sep 2013 20:29:45 +1000 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r85ATYQi10813928; Thu, 5 Sep 2013 20:29:34 +1000 Received: from d23av03.au.ibm.com (localhost [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r85ATiuB013900; Thu, 5 Sep 2013 20:29:45 +1000 Received: from localhost (ericxiao.cn.ibm.com [9.111.29.25]) by d23av03.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id r85AThP2013860; Thu, 5 Sep 2013 20:29:44 +1000 From: Xiao Guangrong To: gleb@redhat.com Cc: avi.kivity@gmail.com, mtosatti@redhat.com, pbonzini@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Xiao Guangrong Subject: [PATCH v2 13/15] KVM: MMU: locklessly write-protect the page Date: Thu, 5 Sep 2013 18:29:16 +0800 Message-Id: <1378376958-27252-14-git-send-email-xiaoguangrong@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1378376958-27252-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> References: <1378376958-27252-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13090510-0260-0000-0000-000003936B2F Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-9.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently, when mark memslot dirty logged or get dirty page, we need to write-protect large guest memory, it is the heavy work, especially, we need to hold mmu-lock which is also required by vcpu to fix its page table fault and mmu-notifier when host page is being changed. In the extreme cpu / memory used guest, it becomes a scalability issue This patch introduces a way to locklessly write-protect guest memory Now, lockless rmap walk, lockless shadow page table access and lockless spte wirte-protection are ready, it is the time to implements page write-protection out of mmu-lock Signed-off-by: Xiao Guangrong --- arch/x86/include/asm/kvm_host.h | 4 ---- arch/x86/kvm/mmu.c | 53 +++++++++++++++++++++++++++++------------ arch/x86/kvm/mmu.h | 6 +++++ arch/x86/kvm/x86.c | 11 ++++----- 4 files changed, 49 insertions(+), 25 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 8e4ca0d..00b44b1 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -789,10 +789,6 @@ void kvm_mmu_set_mask_ptes(u64 user_mask, u64 accessed_mask, u64 dirty_mask, u64 nx_mask, u64 x_mask); int kvm_mmu_reset_context(struct kvm_vcpu *vcpu); -void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot); -void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, - struct kvm_memory_slot *slot, - gfn_t gfn_offset, unsigned long mask); void kvm_mmu_zap_all(struct kvm *kvm); void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm); unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm); diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index f551fc7..44b7822 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1376,8 +1376,31 @@ static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, return flush; } -/** - * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages +static void __rmap_write_protect_lockless(u64 *sptep) +{ + u64 spte; + int level = page_header(__pa(sptep))->role.level; + +retry: + spte = mmu_spte_get_lockless(sptep); + if (unlikely(!is_last_spte(spte, level) || !is_writable_pte(spte))) + return; + + if (likely(cmpxchg64(sptep, spte, spte & ~PT_WRITABLE_MASK) == spte)) + return; + + goto retry; +} + +static void rmap_write_protect_lockless(unsigned long *rmapp) +{ + pte_list_walk_lockless(rmapp, __rmap_write_protect_lockless); +} + +/* + * kvm_mmu_write_protect_pt_masked_lockless - write protect selected PT level + * pages out of mmu-lock. + * * @kvm: kvm instance * @slot: slot to protect * @gfn_offset: start of the BITS_PER_LONG pages we care about @@ -1386,16 +1409,17 @@ static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, * Used when we do not need to care about huge page mappings: e.g. during dirty * logging we do not have any such mappings. */ -void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, - struct kvm_memory_slot *slot, - gfn_t gfn_offset, unsigned long mask) +void +kvm_mmu_write_protect_pt_masked_lockless(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) { unsigned long *rmapp; while (mask) { rmapp = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), PT_PAGE_TABLE_LEVEL, slot); - __rmap_write_protect(kvm, rmapp, false); + rmap_write_protect_lockless(rmapp); /* clear the first set bit */ mask &= mask - 1; @@ -4547,7 +4571,7 @@ int kvm_mmu_setup(struct kvm_vcpu *vcpu) return init_kvm_mmu(vcpu); } -void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) +void kvm_mmu_slot_remove_write_access_lockless(struct kvm *kvm, int slot) { struct kvm_memory_slot *memslot; gfn_t last_gfn; @@ -4556,8 +4580,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) memslot = id_to_memslot(kvm->memslots, slot); last_gfn = memslot->base_gfn + memslot->npages - 1; - spin_lock(&kvm->mmu_lock); - + kvm_mmu_rcu_free_page_begin(kvm); for (i = PT_PAGE_TABLE_LEVEL; i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) { unsigned long *rmapp; @@ -4567,15 +4590,15 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) last_index = gfn_to_index(last_gfn, memslot->base_gfn, i); for (index = 0; index <= last_index; ++index, ++rmapp) { - if (*rmapp) - __rmap_write_protect(kvm, rmapp, false); + rmap_write_protect_lockless(rmapp); - if (need_resched() || spin_needbreak(&kvm->mmu_lock)) - cond_resched_lock(&kvm->mmu_lock); + if (need_resched()) { + kvm_mmu_rcu_free_page_end(kvm); + kvm_mmu_rcu_free_page_begin(kvm); + } } } - - spin_unlock(&kvm->mmu_lock); + kvm_mmu_rcu_free_page_end(kvm); /* * We can flush all the TLBs out of the mmu lock without TLB diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index 61217f3..2ac649e 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -139,4 +139,10 @@ static inline void kvm_mmu_rcu_free_page_end(struct kvm *kvm) rcu_read_unlock(); } + +void kvm_mmu_slot_remove_write_access_lockless(struct kvm *kvm, int slot); +void +kvm_mmu_write_protect_pt_masked_lockless(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask); #endif diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 5582b66..33d483a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3543,8 +3543,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) dirty_bitmap_buffer = dirty_bitmap + n / sizeof(long); memset(dirty_bitmap_buffer, 0, n); - spin_lock(&kvm->mmu_lock); - + kvm_mmu_rcu_free_page_begin(kvm); for (i = 0; i < n / sizeof(long); i++) { unsigned long mask; gfn_t offset; @@ -3568,10 +3567,10 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log) dirty_bitmap_buffer[i] = mask; offset = i * BITS_PER_LONG; - kvm_mmu_write_protect_pt_masked(kvm, memslot, offset, mask); + kvm_mmu_write_protect_pt_masked_lockless(kvm, memslot, + offset, mask); } - - spin_unlock(&kvm->mmu_lock); + kvm_mmu_rcu_free_page_end(kvm); /* * All the TLBs can be flushed out of mmu lock, see the comments in @@ -7231,7 +7230,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, * See the comments in fast_page_fault(). */ if ((change != KVM_MR_DELETE) && (mem->flags & KVM_MEM_LOG_DIRTY_PAGES)) - kvm_mmu_slot_remove_write_access(kvm, mem->slot); + kvm_mmu_slot_remove_write_access_lockless(kvm, mem->slot); } void kvm_arch_flush_shadow_all(struct kvm *kvm)