KVM: s390: vsie: speed up VCPU irq delivery when handling vsie

Whenever we want to wake up a VCPU (e.g. when injecting an IRQ), we
have to kick it out of vsie, so the request will be handled faster.

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 190ad63..946fc86 100644 (file)
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -549,6 +549,8 @@ struct kvm_guestdbg_info_arch {
 
 struct kvm_vcpu_arch {
        struct kvm_s390_sie_block *sie_block;
+       /* if vsie is active, currently executed shadow sie control block */
+       struct kvm_s390_sie_block *vsie_block;
        unsigned int      host_acrs[NUM_ACRS];
        struct fpu        host_fpregs;
        struct kvm_s390_local_interrupt local_int;

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index d72c4a8..ca19627 100644 (file)
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -995,6 +995,11 @@ void kvm_s390_vcpu_wakeup(struct kvm_vcpu *vcpu)
                swake_up(&vcpu->wq);
                vcpu->stat.halt_wakeup++;
        }
+       /*
+        * The VCPU might not be sleeping but is executing the VSIE. Let's
+        * kick it, so it leaves the SIE to process the request.
+        */
+       kvm_s390_vsie_kick(vcpu);
 }
 
 enum hrtimer_restart kvm_s390_idle_wakeup(struct hrtimer *timer)

diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index b137fba..ffbbdd2 100644 (file)
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -254,6 +254,7 @@ int kvm_s390_handle_eb(struct kvm_vcpu *vcpu);
 
 /* implemented in vsie.c */
 int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu);
+void kvm_s390_vsie_kick(struct kvm_vcpu *vcpu);
 void kvm_s390_vsie_gmap_notifier(struct gmap *gmap, unsigned long start,
                                 unsigned long end);
 void kvm_s390_vsie_init(struct kvm *kvm);

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 7482488..c8c8763 100644 (file)
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -838,6 +838,23 @@ static int acquire_gmap_shadow(struct kvm_vcpu *vcpu,
 }
 
 /*
+ * Register the shadow scb at the VCPU, e.g. for kicking out of vsie.
+ */
+static void register_shadow_scb(struct kvm_vcpu *vcpu,
+                               struct vsie_page *vsie_page)
+{
+       WRITE_ONCE(vcpu->arch.vsie_block, &vsie_page->scb_s);
+}
+
+/*
+ * Unregister a shadow scb from a VCPU.
+ */
+static void unregister_shadow_scb(struct kvm_vcpu *vcpu)
+{
+       WRITE_ONCE(vcpu->arch.vsie_block, NULL);
+}
+
+/*
  * Run the vsie on a shadowed scb, managing the gmap shadow, handling
  * prefix pages and faults.
  *
@@ -860,6 +877,7 @@ static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
                        rc = do_vsie_run(vcpu, vsie_page);
                        gmap_enable(vcpu->arch.gmap);
                }
+               atomic_andnot(PROG_BLOCK_SIE, &scb_s->prog20);
 
                if (rc == -EAGAIN)
                        rc = 0;
@@ -1000,7 +1018,9 @@ int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu)
        rc = pin_blocks(vcpu, vsie_page);
        if (rc)
                goto out_unshadow;
+       register_shadow_scb(vcpu, vsie_page);
        rc = vsie_run(vcpu, vsie_page);
+       unregister_shadow_scb(vcpu);
        unpin_blocks(vcpu, vsie_page);
 out_unshadow:
        unshadow_scb(vcpu, vsie_page);
@@ -1039,3 +1059,18 @@ void kvm_s390_vsie_destroy(struct kvm *kvm)
        kvm->arch.vsie.page_count = 0;
        mutex_unlock(&kvm->arch.vsie.mutex);
 }
+
+void kvm_s390_vsie_kick(struct kvm_vcpu *vcpu)
+{
+       struct kvm_s390_sie_block *scb = READ_ONCE(vcpu->arch.vsie_block);
+
+       /*
+        * Even if the VCPU lets go of the shadow sie block reference, it is
+        * still valid in the cache. So we can safely kick it.
+        */
+       if (scb) {
+               atomic_or(PROG_BLOCK_SIE, &scb->prog20);
+               if (scb->prog0c & PROG_IN_SIE)
+                       atomic_or(CPUSTAT_STOP_INT, &scb->cpuflags);
+       }
+}