git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From 8d5678a76689acbf91245a3791fe853ab773090f Mon Sep 17 00:00:00 2001
   2 From: Hou Wenlong <houwenlong.hwl@antgroup.com>
   3 Date: Tue, 15 Mar 2022 17:35:13 +0800
   4 Subject: KVM: x86/mmu: Don't rebuild page when the page is synced and no tlb flushing is required
   5
   6 From: Hou Wenlong <houwenlong.hwl@antgroup.com>
   7
   8 commit 8d5678a76689acbf91245a3791fe853ab773090f upstream.
   9
  10 Before Commit c3e5e415bc1e6 ("KVM: X86: Change kvm_sync_page()
  11 to return true when remote flush is needed"), the return value
  12 of kvm_sync_page() indicates whether the page is synced, and
  13 kvm_mmu_get_page() would rebuild page when the sync fails.
  14 But now, kvm_sync_page() returns false when the page is
  15 synced and no tlb flushing is required, which leads to
  16 rebuild page in kvm_mmu_get_page(). So return the return
  17 value of mmu->sync_page() directly and check it in
  18 kvm_mmu_get_page(). If the sync fails, the page will be
  19 zapped and the invalid_list is not empty, so set flush as
  20 true is accepted in mmu_sync_children().
  21
  22 Cc: stable@vger.kernel.org
  23 Fixes: c3e5e415bc1e6 ("KVM: X86: Change kvm_sync_page() to return true when remote flush is needed")
  24 Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
  25 Acked-by: Lai Jiangshan <jiangshanlai@gmail.com>
  26 Message-Id: <0dabeeb789f57b0d793f85d073893063e692032d.1647336064.git.houwenlong.hwl@antgroup.com>
  27 [mmu_sync_children should not flush if the page is zapped. - Paolo]
  28 Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30 ---
  31  arch/x86/kvm/mmu/mmu.c |   18 +++++++++---------
  32  1 file changed, 9 insertions(+), 9 deletions(-)
  33
  34 --- a/arch/x86/kvm/mmu/mmu.c
  35 +++ b/arch/x86/kvm/mmu/mmu.c
  36 @@ -1843,17 +1843,14 @@ static void kvm_mmu_commit_zap_page(stru
  37           &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)])     \
  38                 if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else
  39
  40 -static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
  41 +static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
  42                          struct list_head *invalid_list)
  43  {
  44         int ret = vcpu->arch.mmu->sync_page(vcpu, sp);
  45
  46 -       if (ret < 0) {
  47 +       if (ret < 0)
  48                 kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
  49 -               return false;
  50 -       }
  51 -
  52 -       return !!ret;
  53 +       return ret;
  54  }
  55
  56  static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm,
  57 @@ -1975,7 +1972,7 @@ static int mmu_sync_children(struct kvm_
  58
  59                 for_each_sp(pages, sp, parents, i) {
  60                         kvm_unlink_unsync_page(vcpu->kvm, sp);
  61 -                       flush |= kvm_sync_page(vcpu, sp, &invalid_list);
  62 +                       flush |= kvm_sync_page(vcpu, sp, &invalid_list) > 0;
  63                         mmu_pages_clear_parents(&parents);
  64                 }
  65                 if (need_resched() || rwlock_needbreak(&vcpu->kvm->mmu_lock)) {
  66 @@ -2016,6 +2013,7 @@ static struct kvm_mmu_page *kvm_mmu_get_
  67         struct hlist_head *sp_list;
  68         unsigned quadrant;
  69         struct kvm_mmu_page *sp;
  70 +       int ret;
  71         int collisions = 0;
  72         LIST_HEAD(invalid_list);
  73
  74 @@ -2068,11 +2066,13 @@ static struct kvm_mmu_page *kvm_mmu_get_
  75                          * If the sync fails, the page is zapped.  If so, break
  76                          * in order to rebuild it.
  77                          */
  78 -                       if (!kvm_sync_page(vcpu, sp, &invalid_list))
  79 +                       ret = kvm_sync_page(vcpu, sp, &invalid_list);
  80 +                       if (ret < 0)
  81                                 break;
  82
  83                         WARN_ON(!list_empty(&invalid_list));
  84 -                       kvm_flush_remote_tlbs(vcpu->kvm);
  85 +                       if (ret > 0)
  86 +                               kvm_flush_remote_tlbs(vcpu->kvm);
  87                 }
  88
  89                 __clear_sp_write_flooding_count(sp);