[PATCH 38/39] KVM: s390: Make facility bits future-proof

[Avi Kivity]

From: Christian Borntraeger <borntraeger@xxxxxxxxxx>

Heiko Carstens pointed out, that its safer to activate working facilities
instead of disabling problematic facilities. The new code uses the host
facility bits and masks it with known good ones.

Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>
---
 arch/s390/kvm/priv.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index d1faf5c..cce40ff 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -157,8 +157,8 @@ static int handle_stfl(struct kvm_vcpu *vcpu)
 	int rc;
 
 	vcpu->stat.instruction_stfl++;
-	facility_list &= ~(1UL<<24); /* no stfle */
-	facility_list &= ~(1UL<<23); /* no large pages */
+	/* only pass the facility bits, which we can handle */
+	facility_list &= 0xfe00fff3;
 
 	rc = copy_to_guest(vcpu, offsetof(struct _lowcore, stfl_fac_list),
 			   &facility_list, sizeof(facility_list));
-- 
1.6.0.1

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