diff mbox series

[v4,14/14] KVM: SVM: Skip SEV cache flush if no ASIDs have been used

Message ID 20210306015905.186698-15-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: SVM: Misc SEV cleanups | expand

Commit Message

Sean Christopherson March 6, 2021, 1:59 a.m. UTC
Skip SEV's expensive WBINVD and DF_FLUSH if there are no SEV ASIDs
waiting to be reclaimed, e.g. if SEV was never used.  This "fixes" an
issue where the DF_FLUSH fails during hardware teardown if the original
SEV_INIT failed.  Ideally, SEV wouldn't be marked as enabled in KVM if
SEV_INIT fails, but that's a problem for another day.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/sev.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 3bf04a697723..f8ebda7c365a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -57,9 +57,14 @@  struct enc_region {
 	unsigned long size;
 };
 
-static int sev_flush_asids(void)
+static int sev_flush_asids(int min_asid, int max_asid)
 {
-	int ret, error = 0;
+	int ret, pos, error = 0;
+
+	/* Check if there are any ASIDs to reclaim before performing a flush */
+	pos = find_next_bit(sev_reclaim_asid_bitmap, max_sev_asid, min_asid);
+	if (pos >= max_asid)
+		return -EBUSY;
 
 	/*
 	 * DEACTIVATE will clear the WBINVD indicator causing DF_FLUSH to fail,
@@ -81,14 +86,7 @@  static int sev_flush_asids(void)
 /* Must be called with the sev_bitmap_lock held */
 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_asid);
-	if (pos >= max_asid)
-		return false;
-
-	if (sev_flush_asids())
+	if (sev_flush_asids(min_asid, max_asid))
 		return false;
 
 	/* The flush process will flush all reclaimable SEV and SEV-ES ASIDs */
@@ -1399,10 +1397,11 @@  void sev_hardware_teardown(void)
 	if (!sev_enabled)
 		return;
 
+	/* No need to take sev_bitmap_lock, all VMs have been destroyed. */
+	sev_flush_asids(0, max_sev_asid);
+
 	bitmap_free(sev_asid_bitmap);
 	bitmap_free(sev_reclaim_asid_bitmap);
-
-	sev_flush_asids();
 }
 
 int sev_cpu_init(struct svm_cpu_data *sd)