Commit 469bb32b authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: SVM: Skip SEV cache flush if no ASIDs have been used 



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: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210422021125.3417167-16-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 82b7ae04

arch/x86/kvm/svm/sev.c

+13 −12
Original line number Diff line number Diff line
@@ -74,9 +74,15 @@ struct enc_region { 
	unsigned long size;

};



static int sev_flush_asids(void)

/* Called with the sev_bitmap_lock held, or on shutdown  */

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_asid, min_asid);

	if (pos >= max_asid)

		return -EBUSY;



	/*

	 * DEACTIVATE will clear the WBINVD indicator causing DF_FLUSH to fail,
@@ -103,14 +109,7 @@ static inline bool is_mirroring_enc_context(struct kvm *kvm) 
/* 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 */
@@ -1897,12 +1896,14 @@ 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);



	misc_cg_set_capacity(MISC_CG_RES_SEV, 0);

	misc_cg_set_capacity(MISC_CG_RES_SEV_ES, 0);



	sev_flush_asids();

}



int sev_cpu_init(struct svm_cpu_data *sd)