KVM: MMU: rewrite audit_mappings_page() function

There is a bugs in this function, we call gfn_to_pfn() and kvm_mmu_gva_to_gpa_read() in
atomic context(kvm_mmu_audit() is called under the spinlock(mmu_lock)'s protection).

This patch fix it by:
- introduce gfn_to_pfn_atomic instead of gfn_to_pfn
- get the mapping gfn from kvm_mmu_page_get_gfn()

And it adds 'notrap' ptes check in unsync/direct sps

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 40 insertions, 35 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 68575dc32ec7..0d91f60af1a8 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3487,15 +3487,6 @@ EXPORT_SYMBOL_GPL(kvm_mmu_get_spte_hierarchy);
 
 static const char *audit_msg;
 
-static gva_t canonicalize(gva_t gva)
-{
-#ifdef CONFIG_X86_64
-        gva = (long long)(gva << 16) >> 16;
-#endif
-        return gva;
-}
-
-
 typedef void (*inspect_spte_fn) (struct kvm *kvm, u64 *sptep);
 
 static void __mmu_spte_walk(struct kvm *kvm, struct kvm_mmu_page *sp,
@@ -3550,39 +3541,53 @@ static void audit_mappings_page(struct kvm_vcpu *vcpu, u64 page_pte,
         gva_t va_delta = 1ul << (PAGE_SHIFT + 9 * (level - 1));
 
         for (i = 0; i < PT64_ENT_PER_PAGE; ++i, va += va_delta) {
-                u64 ent = pt[i];
+                u64 *sptep = pt + i;
+                struct kvm_mmu_page *sp;
+                gfn_t gfn;
+                pfn_t pfn;
+                hpa_t hpa;
 
-                if (ent == shadow_trap_nonpresent_pte)
-                        continue;
+                sp = page_header(__pa(sptep));
 
-                va = canonicalize(va);
-                if (is_shadow_present_pte(ent) && !is_last_spte(ent, level))
-                        audit_mappings_page(vcpu, ent, va, level - 1);
-                else {
-                        gpa_t gpa = kvm_mmu_gva_to_gpa_read(vcpu, va, NULL);
-                        gfn_t gfn = gpa >> PAGE_SHIFT;
-                        pfn_t pfn = gfn_to_pfn(vcpu->kvm, gfn);
-                        hpa_t hpa = (hpa_t)pfn << PAGE_SHIFT;
+                if (sp->unsync) {
+                        if (level != PT_PAGE_TABLE_LEVEL) {
+                                printk(KERN_ERR "audit: (%s) error: unsync sp: %p level = %d\n",
+                                                audit_msg, sp, level);
+                                return;
+                        }
 
-                        if (is_error_pfn(pfn)) {
-                                kvm_release_pfn_clean(pfn);
-                                continue;
+                        if (*sptep == shadow_notrap_nonpresent_pte) {
+                                printk(KERN_ERR "audit: (%s) error: notrap spte in unsync sp: %p\n",
+                                                audit_msg, sp);
+                                return;
                         }
+                }
 
-                        if (is_shadow_present_pte(ent)
-                            && (ent & PT64_BASE_ADDR_MASK) != hpa)
-                                printk(KERN_ERR "xx audit error: (%s) levels %d"
-                                       " gva %lx gpa %llx hpa %llx ent %llx %d\n",
-                                       audit_msg, vcpu->arch.mmu.root_level,
-                                       va, gpa, hpa, ent,
-                                       is_shadow_present_pte(ent));
-                        else if (ent == shadow_notrap_nonpresent_pte
-                                 && !is_error_hpa(hpa))
-                                printk(KERN_ERR "audit: (%s) notrap shadow,"
-                                       " valid guest gva %lx\n", audit_msg, va);
-                        kvm_release_pfn_clean(pfn);
+                if (sp->role.direct && *sptep == shadow_notrap_nonpresent_pte) {
+                        printk(KERN_ERR "audit: (%s) error: notrap spte in direct sp: %p\n",
+                                        audit_msg, sp);
+                        return;
+                }
+
+                if (!is_shadow_present_pte(*sptep) ||
+                      !is_last_spte(*sptep, level))
+                        return;
+
+                gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
+                pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn);
 
+                if (is_error_pfn(pfn)) {
+                        kvm_release_pfn_clean(pfn);
+                        return;
                 }
+
+                hpa =  pfn << PAGE_SHIFT;
+
+                if ((*sptep & PT64_BASE_ADDR_MASK) != hpa)
+                        printk(KERN_ERR "xx audit error: (%s) levels %d"
+                                           " gva %lx pfn %llx hpa %llx ent %llxn",
+                                           audit_msg, vcpu->arch.mmu.root_level,
+                                           va, pfn, hpa, *sptep);
         }
 }