KVM: SVM: Update ASID allocation to support SEV-ES guests

SEV and SEV-ES guests each have dedicated ASID ranges. Update the ASID
allocation routine to return an ASID in the respective range.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <d7aed505e31e3954268b2015bb60a1486269c780.1607620209.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/sev.c

@@ -61,19 +61,19 @@ static int sev_flush_asids(void)
 }
 
 /* Must be called with the sev_bitmap_lock held */
-static bool __sev_recycle_asids(void)
+static bool __sev_recycle_asids(int min_asid, int max_asid)
 {
 	int pos;
 
 	/* Check if there are any ASIDs to reclaim before performing a flush */
-	pos = find_next_bit(sev_reclaim_asid_bitmap,
-			    max_sev_asid, min_sev_asid - 1);
-	if (pos >= max_sev_asid)
+	pos = find_next_bit(sev_reclaim_asid_bitmap, max_sev_asid, min_asid);
+	if (pos >= max_asid)
 		return false;
 
 	if (sev_flush_asids())
 		return false;
 
+	/* The flush process will flush all reclaimable SEV and SEV-ES ASIDs */
 	bitmap_xor(sev_asid_bitmap, sev_asid_bitmap, sev_reclaim_asid_bitmap,
 		   max_sev_asid);
 	bitmap_zero(sev_reclaim_asid_bitmap, max_sev_asid);
@@ -81,20 +81,23 @@ static bool __sev_recycle_asids(void)
 	return true;
 }
 
-static int sev_asid_new(void)
+static int sev_asid_new(struct kvm_sev_info *sev)
 {
+	int pos, min_asid, max_asid;
 	bool retry = true;
-	int pos;
 
 	mutex_lock(&sev_bitmap_lock);
 
 	/*
-	 * SEV-enabled guest must use asid from min_sev_asid to max_sev_asid.
+	 * SEV-enabled guests must use asid from min_sev_asid to max_sev_asid.
+	 * SEV-ES-enabled guest can use from 1 to min_sev_asid - 1.
 	 */
+	min_asid = sev->es_active ? 0 : min_sev_asid - 1;
+	max_asid = sev->es_active ? min_sev_asid - 1 : max_sev_asid;
 again:
-	pos = find_next_zero_bit(sev_asid_bitmap, max_sev_asid, min_sev_asid - 1);
-	if (pos >= max_sev_asid) {
-		if (retry && __sev_recycle_asids()) {
+	pos = find_next_zero_bit(sev_asid_bitmap, max_sev_asid, min_asid);
+	if (pos >= max_asid) {
+		if (retry && __sev_recycle_asids(min_asid, max_asid)) {
 			retry = false;
 			goto again;
 		}
@@ -176,7 +179,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	if (unlikely(sev->active))
 		return ret;
 
-	asid = sev_asid_new();
+	asid = sev_asid_new(sev);
 	if (asid < 0)
 		return ret;