KVM: nVMX: delay loading of PDPTRs to KVM_REQ_GET_NESTED_STATE_PAGES

Similar to the rest of guest page accesses after a migration,
this access should be delayed to KVM_REQ_GET_NESTED_STATE_PAGES.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210607090203.133058-6-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 47f4aa609778859113fec1adee73cf9cfef1c36c..ac306678afccd6580df3575bd94d5ac20ad30c24 100644 (file)
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1105,7 +1105,8 @@ static bool nested_vmx_transition_mmu_sync(struct kvm_vcpu *vcpu)
  * Exit Qualification (for a VM-Entry consistency check VM-Exit) is assigned to
  * @entry_failure_code.
  */
-static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool nested_ept,
+static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
+                              bool nested_ept, bool reload_pdptrs,
                               enum vm_entry_failure_code *entry_failure_code)
 {
        if (CC(kvm_vcpu_is_illegal_gpa(vcpu, cr3))) {
@@ -1117,7 +1118,7 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne
         * If PAE paging and EPT are both on, CR3 is not used by the CPU and
         * must not be dereferenced.
         */
-       if (!nested_ept && is_pae_paging(vcpu) &&
+       if (reload_pdptrs && !nested_ept && is_pae_paging(vcpu) &&
            CC(!load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3))) {
                *entry_failure_code = ENTRY_FAIL_PDPTE;
                return -EINVAL;
@@ -2487,6 +2488,7 @@ static void prepare_vmcs02_rare(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
  * is assigned to entry_failure_code on failure.
  */
 static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
+                         bool from_vmentry,
                          enum vm_entry_failure_code *entry_failure_code)
 {
        struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -2579,7 +2581,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 
        /* Shadow page tables on either EPT or shadow page tables. */
        if (nested_vmx_load_cr3(vcpu, vmcs12->guest_cr3, nested_cpu_has_ept(vmcs12),
-                               entry_failure_code))
+                               from_vmentry, entry_failure_code))
                return -EINVAL;
 
        /*
@@ -3120,6 +3122,17 @@ static bool nested_get_vmcs12_pages(struct kvm_vcpu *vcpu)
        struct page *page;
        u64 hpa;
 
+       if (!nested_cpu_has_ept(vmcs12) && is_pae_paging(vcpu)) {
+               /*
+                * Reload the guest's PDPTRs since after a migration
+                * the guest CR3 might be restored prior to setting the nested
+                * state which can lead to a load of wrong PDPTRs.
+                */
+               if (CC(!load_pdptrs(vcpu, vcpu->arch.walk_mmu, vcpu->arch.cr3)))
+                       return false;
+       }
+
+
        if (nested_cpu_has2(vmcs12, SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES)) {
                /*
                 * Translate L1 physical address to host physical
@@ -3371,7 +3384,7 @@ enum nvmx_vmentry_status nested_vmx_enter_non_root_mode(struct kvm_vcpu *vcpu,
 
        enter_guest_mode(vcpu);
 
-       if (prepare_vmcs02(vcpu, vmcs12, &entry_failure_code)) {
+       if (prepare_vmcs02(vcpu, vmcs12, from_vmentry, &entry_failure_code)) {
                exit_reason.basic = EXIT_REASON_INVALID_STATE;
                vmcs12->exit_qualification = entry_failure_code;
                goto vmentry_fail_vmexit_guest_mode;
@@ -4226,7 +4239,7 @@ static void load_vmcs12_host_state(struct kvm_vcpu *vcpu,
         * Only PDPTE load can fail as the value of cr3 was checked on entry and
         * couldn't have changed.
         */
-       if (nested_vmx_load_cr3(vcpu, vmcs12->host_cr3, false, &ignored))
+       if (nested_vmx_load_cr3(vcpu, vmcs12->host_cr3, false, true, &ignored))
                nested_vmx_abort(vcpu, VMX_ABORT_LOAD_HOST_PDPTE_FAIL);
 
        nested_vmx_transition_tlb_flush(vcpu, vmcs12, false);