[SRU][F][PATCH 2/3] KVM: s390: pv: avoid stalls for kvm_s390_pv_init_vm

frank.heimes at canonical.com frank.heimes at canonical.com
Tue Jun 21 19:36:58 UTC 2022

From: Claudio Imbrenda <imbrenda at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1979296

When the system is heavily overcommitted, kvm_s390_pv_init_vm might
generate stall notifications.

Fix this by using uv_call_sched instead of just uv_call. This is ok because
we are not holding spinlocks.

Signed-off-by: Claudio Imbrenda <imbrenda at linux.ibm.com>
Fixes: 214d9bbcd3a672 ("s390/mm: provide memory management functions for protected KVM guests")
Reviewed-by: Christian Borntraeger <borntraeger at de.ibm.com>
Reviewed-by: Janosch Frank <frankja at linux.ibm.com>
Message-Id: <20210920132502.36111-4-imbrenda at linux.ibm.com>
Signed-off-by: Janosch Frank <frankja at linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger at de.ibm.com>
(cherry picked from commit 1e2aa46de526a5adafe580bca4c25856bb06f09e)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
 arch/s390/kvm/pv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 63e330109b63..06152f33cbb7 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -192,7 +192,7 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
 	uvcb.conf_base_stor_origin = (u64)kvm->arch.pv.stor_base;
 	uvcb.conf_virt_stor_origin = (u64)kvm->arch.pv.stor_var;
-	cc = uv_call(0, (u64)&uvcb);
+	cc = uv_call_sched(0, (u64)&uvcb);
 	*rc = uvcb.header.rc;
 	*rrc = uvcb.header.rrc;
 	KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x",

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