diff options
Diffstat (limited to 'arch/x86/kvm/mmu/paging_tmpl.h')
| -rw-r--r-- | arch/x86/kvm/mmu/paging_tmpl.h | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index efce0a935e23..913d52a7923e 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -707,8 +707,27 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gpa_t addr, if (!is_shadow_present_pte(*it.sptep)) { table_gfn = gw->table_gfn[it.level - 2]; access = gw->pt_access[it.level - 2]; - sp = kvm_mmu_get_page(vcpu, table_gfn, addr, it.level-1, - false, access); + sp = kvm_mmu_get_page(vcpu, table_gfn, addr, + it.level-1, false, access); + /* + * We must synchronize the pagetable before linking it + * because the guest doesn't need to flush tlb when + * the gpte is changed from non-present to present. + * Otherwise, the guest may use the wrong mapping. + * + * For PG_LEVEL_4K, kvm_mmu_get_page() has already + * synchronized it transiently via kvm_sync_page(). + * + * For higher level pagetable, we synchronize it via + * the slower mmu_sync_children(). If it needs to + * break, some progress has been made; return + * RET_PF_RETRY and retry on the next #PF. + * KVM_REQ_MMU_SYNC is not necessary but it + * expedites the process. + */ + if (sp->unsync_children && + mmu_sync_children(vcpu, sp, false)) + return RET_PF_RETRY; } /* |