KVM: x86/mmu: Fix TDP MMU page table level

BugLink: https://bugs.launchpad.net/bugs/1956791
TDP MMU iterator's level is identical to page table's actual level.  For
instance, for the last level page table (whose entry points to one 4K
page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging,
the iter->level is mmu->shadow_root_level, which is 5.  However, struct
kvm_mmu_page's level currently is not set correctly when it is allocated
in kvm_tdp_mmu_map().  When iterator hits non-present SPTE and needs to
allocate a new child page table, currently iter->level, which is the
level of the page table where the non-present SPTE belongs to, is used.
This results in struct kvm_mmu_page's level always having its parent's
level (excpet root table's level, which is initialized explicitly using
mmu->shadow_root_level).

This is kinda wrong, and not consistent with existing non TDP MMU code.
Fortuantely sp->role.level is only used in handle_removed_tdp_mmu_page()
and kvm_tdp_mmu_zap_sp(), and they are already aware of this and behave
correctly.  However to make it consistent with legacy MMU code (and fix
the issue that both root page table and its child page table have
shadow_root_level), use iter->level - 1 in kvm_tdp_mmu_map(), and change
handle_removed_tdp_mmu_page() and kvm_tdp_mmu_zap_sp() accordingly.

Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Kai Huang <kai.huang@intel.com>
Message-Id: <bcb6569b6e96cb78aaa7b50640e6e6b53291a74e.1623717884.git.kai.huang@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit f1b8325508327a302f1d5cd8a4bf51e2c9c72fa9)
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 3c225bc0c08262b70cfc09a64cf8fc4f50eadd4f..19a97ae4e7f0bc97dc332461f0524a3331e213f5 100644 (file)
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -334,7 +334,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt,
 
        for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
                sptep = rcu_dereference(pt) + i;
-               gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1));
+               gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level);
 
                if (shared) {
                        /*
@@ -376,12 +376,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt,
                        WRITE_ONCE(*sptep, REMOVED_SPTE);
                }
                handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn,
-                                   old_child_spte, REMOVED_SPTE, level - 1,
+                                   old_child_spte, REMOVED_SPTE, level,
                                    shared);
        }
 
        kvm_flush_remote_tlbs_with_address(kvm, gfn,
-                                          KVM_PAGES_PER_HPAGE(level));
+                                          KVM_PAGES_PER_HPAGE(level + 1));
 
        call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback);
 }
@@ -1040,7 +1040,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
                        if (is_removed_spte(iter.old_spte))
                                break;
 
-                       sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level);
+                       sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1);
                        child_pt = sp->spt;
 
                        new_spte = make_nonleaf_spte(child_pt,

diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index 5fdf630904517a7cc2281cc0206741e968f5459d..7f9974c5d0b4d2c41d95d759874aa06558377635 100644 (file)
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -31,7 +31,7 @@ static inline bool kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id,
 }
 static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
-       gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level);
+       gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1);
 
        /*
         * Don't allow yielding, as the caller may have a flush pending.  Note,