[PATCH v1 10/11] KVM: s390: pv: module parameter to fence lazy destroy

Claudio Imbrenda
2021-05-17T20:08:43Z

Add the module parameter "lazy_destroy", to allow the lazy destroy
mechanism to be switched off. This might be useful for debugging
purposes.

The parameter is enabled by default.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
arch/s390/kvm/pv.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 4333d3e54ef0..00c14406205f 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -26,6 +26,10 @@ struct deferred_priv {
unsigned long real;
};

+static int lazy_destroy = 1;
+module_param(lazy_destroy, int, 0444);
+MODULE_PARM_DESC(lazy_destroy, "Deferred destroy for protected guests");
+
int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc)
{
int cc = 0;
@@ -348,6 +352,9 @@ int kvm_s390_pv_deinit_vm_deferred(struct kvm *kvm, u16 *rc, u16 *rrc)
{
struct deferred_priv *priv;

+ if (!lazy_destroy)
+ kvm_s390_pv_deinit_vm_now(kvm, rc, rrc);
+
priv = kmalloc(sizeof(*priv), GFP_KERNEL | __GFP_ZERO);
if (!priv)
return kvm_s390_pv_deinit_vm_now(kvm, rc, rrc);
@@ -396,6 +403,12 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
/* Outputs */
kvm->arch.pv.handle = uvcb.guest_handle;

+ if (!lazy_destroy) {
+ mmap_write_lock(kvm->mm);
+ kvm->mm->context.pv_sync_destroy = 1;
+ mmap_write_unlock(kvm->mm);
+ }
+
atomic_inc(&kvm->mm->context.is_protected);
if (cc) {
if (uvcb.header.rc & UVC_RC_NEED_DESTROY) {
--
2.31.1