[RFC PATCH v2 10/25] KVM: nSVM: Add a placeholder ASID for L2

[Yosry Ahmed <yosry@kernel.org>]

In preparation for introducing a separate ASID for L2, introduce a
'placeholder' ASID that is still the same as L1's ASID. This will
facilitate future changes that need to distinguish L1 and L2's ASIDs,
before actually using a different ASID for L1 and L2.

No functional change intended.

Signed-off-by: Yosry Ahmed <yosry@kernel.org>
---
 arch/x86/kvm/svm/nested.c | 5 +++--
 arch/x86/kvm/svm/svm.h    | 2 ++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 66c5b5131cbb1..bc8c466a1f821 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -698,7 +698,6 @@ static void nested_svm_transition_tlb_flush(struct kvm_vcpu *vcpu)
 	 *  - Honor L1's request to flush an ASID on nested VMRUN
 	 *  - Sync nested NPT MMU on VMRUN that flushes L2's ASID[*]
 	 *  - Don't crush a pending TLB flush in vmcb02 on nested VMRUN
-	 *  - Flush L1's ASID on KVM_REQ_TLB_FLUSH_GUEST
 	 *
 	 * [*] Unlike nested EPT, SVM's ASID management can invalidate nested
 	 *     NPT guest-physical mappings on VMRUN.
@@ -925,7 +924,7 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm)
 	else
 		vmcb02->control.bus_lock_counter = 0;
 
-	vmcb02->control.asid = vmcb01->control.asid;
+	vmcb02->control.asid = svm->nested.asid02;
 
 	/* Overwritten later if necessary.  */
 	vmcb_clr_flush_asid(vmcb02);
@@ -1495,6 +1494,8 @@ int svm_allocate_nested(struct vcpu_svm *svm)
 	if (!svm->nested.msrpm)
 		goto err_free_vmcb02;
 
+	svm->nested.asid02 = svm->asid;
+
 	svm->nested.initialized = true;
 	return 0;
 
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 4442e9fd4f5d0..6e98e02f7b8d5 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -232,6 +232,8 @@ struct svm_nested_state {
 	 */
 	struct vmcb_save_area_cached save;
 
+	kvm_tlb_tag_t asid02;
+
 	bool initialized;
 
 	/*
-- 
2.54.0.1136.gdb2ca164c4-goog