Re: [PATCH v2 09/12] KVM: s390: add function process_gib_alert_list()

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On 26.11.18 16:57, Cornelia Huck wrote:
On Mon, 19 Nov 2018 18:25:33 +0100
Michael Mueller <mimu@xxxxxxxxxxxxx> wrote:

This function processes a gib alert list. It is required to
run when either a gib alert interruption has been received or
a gisa that might be in the alert list is cleared or dropped.

Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
---
  arch/s390/kvm/interrupt.c | 28 ++++++++++++++++++++++++++++
  1 file changed, 28 insertions(+)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 8676596f6b5c..443d1804d611 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2910,6 +2910,34 @@ static void nullify_gisa(struct kvm_s390_gisa *gisa)
  	gisa->next_alert = (u32)(u64)gisa;
  }
+/*
+ * Before processing, the gib alert list needs to be cut-off from
+ * the gib by means of function unlink_gib_alert_list(). If non NULL,
+ * the list is processed from its latest to oldest entry.
+ *
+ * Processing an gisa entry needs to wake-up a vcpu of the kvm this gisa
+ * belongs to. Thus, the pending guest interruption will be processed
+ * in SIE context.
+ */
+static void __maybe_unused process_gib_alert_list(void)
+{
+	struct kvm_s390_gisa *gisa = unlink_gib_alert_list();
+	struct kvm_s390_gisa *next_alert;
+	struct kvm_vcpu *vcpu;
+	struct kvm *kvm;
+
+	for (; gisa; gisa = next_alert) {
+		next_alert = (struct kvm_s390_gisa *)(u64)gisa->next_alert;
+		/* unlink from alert list */
+		gisa->next_alert = (u32)(u64)gisa;

The check goes here.

+		/* wake-up a vcpu of the kvm this gisa belongs to */
+		kvm = container_of(gisa, struct sie_page2, gisa)->kvm;
+		vcpu = __find_vcpu_for_floating_irq(kvm);
+		if (vcpu)
+			kvm_s390_vcpu_wakeup(vcpu);

Just to check if I understood correctly: This loop is where you'll add
the extra check whether the interrupt has already been delivered, right?

That's correct!

+	}
+}
+
  void kvm_s390_gisa_clear(struct kvm *kvm)
  {
  	if (kvm->arch.gisa) {





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