diff mbox series

[v4,4/7] nSVM: use vmcb_save_area_cached in nested_vmcb_valid_sregs()

Message ID 20211103115230.720154-5-eesposit@redhat.com (mailing list archive)
State New, archived
Headers show
Series KVM: nSVM: avoid TOC/TOU race when checking vmcb12 | expand

Commit Message

Emanuele Giuseppe Esposito Nov. 3, 2021, 11:52 a.m. UTC 
Now that struct vmcb_save_area_cached contains the required
vmcb fields values (done in nested_load_save_from_vmcb12()),
check them to see if they are correct in nested_vmcb_valid_sregs().

While at it, rename nested_vmcb_valid_sregs in nested_vmcb_check_save.
_nested_vmcb_check_save takes the additional @save parameter, so it
is helpful when we want to check a non-svm save state, like in
svm_set_nested_state. The reason for that is that save is the L1
state, not L2, so we just check it.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 arch/x86/kvm/svm/nested.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index c04f8750e1f7..692bd38025a9 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -230,8 +230,8 @@  static bool nested_vmcb_check_controls(struct kvm_vcpu *vcpu,
 }
 
 /* Common checks that apply to both L1 and L2 state.  */
-static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu,
-				    struct vmcb_save_area *save)
+static bool _nested_vmcb_check_save(struct kvm_vcpu *vcpu,
+				     struct vmcb_save_area_cached *save)
 {
 	/*
 	 * FIXME: these should be done after copying the fields,
@@ -271,6 +271,14 @@  static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+static bool nested_vmcb_check_save(struct kvm_vcpu *vcpu)
+{
+	struct vcpu_svm *svm = to_svm(vcpu);
+	struct vmcb_save_area_cached *save = &svm->nested.save;
+
+	return _nested_vmcb_check_save(vcpu, save);
+}
+
 static
 void _nested_copy_vmcb_control_to_cache(struct vmcb_control_area *to,
 					struct vmcb_control_area *from)
@@ -673,7 +681,7 @@  int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 	nested_copy_vmcb_control_to_cache(svm, &vmcb12->control);
 	nested_copy_vmcb_save_to_cache(svm, &vmcb12->save);
 
-	if (!nested_vmcb_valid_sregs(vcpu, &vmcb12->save) ||
+	if (!nested_vmcb_check_save(vcpu) ||
 	    !nested_vmcb_check_controls(vcpu, &svm->nested.ctl)) {
 		vmcb12->control.exit_code    = SVM_EXIT_ERR;
 		vmcb12->control.exit_code_hi = 0;
@@ -1298,6 +1306,7 @@  static int svm_set_nested_state(struct kvm_vcpu *vcpu,
 		&user_kvm_nested_state->data.svm[0];
 	struct vmcb_control_area *ctl;
 	struct vmcb_save_area *save;
+	struct vmcb_save_area_cached save_cached;
 	unsigned long cr0;
 	int ret;
 
@@ -1365,10 +1374,11 @@  static int svm_set_nested_state(struct kvm_vcpu *vcpu,
 	 * Validate host state saved from before VMRUN (see
 	 * nested_svm_check_permissions).
 	 */
+	_nested_copy_vmcb_save_to_cache(&save_cached, save);
 	if (!(save->cr0 & X86_CR0_PG) ||
 	    !(save->cr0 & X86_CR0_PE) ||
 	    (save->rflags & X86_EFLAGS_VM) ||
-	    !nested_vmcb_valid_sregs(vcpu, save))
+	    !_nested_vmcb_check_save(vcpu, &save_cached))
 		goto out_free;
 
 	/*