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

Message ID 20210517200758.22593-11-imbrenda@linux.ibm.com (mailing list archive)
State New
Headers show
Series KVM: s390: pv: implement lazy destroy | expand

Commit Message

Claudio Imbrenda May 17, 2021, 8:07 p.m. UTC
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(+)

Comments

Janosch Frank May 27, 2021, 10:35 a.m. UTC | #1
On 5/17/21 10:07 PM, Claudio Imbrenda wrote:
> 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);

I'm pondering if we want to make that writable or not.

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

> +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) {
>
diff mbox series

Patch

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) {