KVM: async_pf: Async page fault support on s390
This patch enables async page faults for s390 kvm guests.
It provides the userspace API to enable and disable_wait this feature.
The disable_wait will enforce that the feature is off by waiting on it.
Also it includes the diagnose code, called by the guest to enable async page faults.
The async page faults will use an already existing guest interface for this
purpose, as described in "CP Programming Services (SC24-6084)".
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 9eec794..d8e9f04 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -152,6 +152,7 @@
#ifdef CONFIG_KVM_S390_UCONTROL
case KVM_CAP_S390_UCONTROL:
#endif
+ case KVM_CAP_ASYNC_PF:
case KVM_CAP_SYNC_REGS:
case KVM_CAP_ONE_REG:
case KVM_CAP_ENABLE_CAP:
@@ -273,6 +274,7 @@
{
VCPU_EVENT(vcpu, 3, "%s", "free cpu");
trace_kvm_s390_destroy_vcpu(vcpu->vcpu_id);
+ kvm_clear_async_pf_completion_queue(vcpu);
if (!kvm_is_ucontrol(vcpu->kvm)) {
clear_bit(63 - vcpu->vcpu_id,
(unsigned long *) &vcpu->kvm->arch.sca->mcn);
@@ -322,6 +324,8 @@
/* Section: vcpu related */
int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
{
+ vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
+ kvm_clear_async_pf_completion_queue(vcpu);
if (kvm_is_ucontrol(vcpu->kvm)) {
vcpu->arch.gmap = gmap_alloc(current->mm);
if (!vcpu->arch.gmap)
@@ -382,6 +386,8 @@
vcpu->arch.guest_fpregs.fpc = 0;
asm volatile("lfpc %0" : : "Q" (vcpu->arch.guest_fpregs.fpc));
vcpu->arch.sie_block->gbea = 1;
+ vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
+ kvm_clear_async_pf_completion_queue(vcpu);
atomic_set_mask(CPUSTAT_STOPPED, &vcpu->arch.sie_block->cpuflags);
}
@@ -713,10 +719,89 @@
return rc;
}
+static void __kvm_inject_pfault_token(struct kvm_vcpu *vcpu, bool start_token,
+ unsigned long token)
+{
+ struct kvm_s390_interrupt inti;
+ inti.parm64 = token;
+
+ if (start_token) {
+ inti.type = KVM_S390_INT_PFAULT_INIT;
+ WARN_ON_ONCE(kvm_s390_inject_vcpu(vcpu, &inti));
+ } else {
+ inti.type = KVM_S390_INT_PFAULT_DONE;
+ WARN_ON_ONCE(kvm_s390_inject_vm(vcpu->kvm, &inti));
+ }
+}
+
+void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu,
+ struct kvm_async_pf *work)
+{
+ trace_kvm_s390_pfault_init(vcpu, work->arch.pfault_token);
+ __kvm_inject_pfault_token(vcpu, true, work->arch.pfault_token);
+}
+
+void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
+ struct kvm_async_pf *work)
+{
+ trace_kvm_s390_pfault_done(vcpu, work->arch.pfault_token);
+ __kvm_inject_pfault_token(vcpu, false, work->arch.pfault_token);
+}
+
+void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu,
+ struct kvm_async_pf *work)
+{
+ /* s390 will always inject the page directly */
+}
+
+bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu)
+{
+ /*
+ * s390 will always inject the page directly,
+ * but we still want check_async_completion to cleanup
+ */
+ return true;
+}
+
+static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu)
+{
+ hva_t hva;
+ struct kvm_arch_async_pf arch;
+ int rc;
+
+ if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
+ return 0;
+ if ((vcpu->arch.sie_block->gpsw.mask & vcpu->arch.pfault_select) !=
+ vcpu->arch.pfault_compare)
+ return 0;
+ if (psw_extint_disabled(vcpu))
+ return 0;
+ if (kvm_cpu_has_interrupt(vcpu))
+ return 0;
+ if (!(vcpu->arch.sie_block->gcr[0] & 0x200ul))
+ return 0;
+ if (!vcpu->arch.gmap->pfault_enabled)
+ return 0;
+
+ hva = gmap_fault(current->thread.gmap_addr, vcpu->arch.gmap);
+ if (copy_from_guest(vcpu, &arch.pfault_token, vcpu->arch.pfault_token, 8))
+ return 0;
+
+ rc = kvm_setup_async_pf(vcpu, current->thread.gmap_addr, hva, &arch);
+ return rc;
+}
+
static int vcpu_pre_run(struct kvm_vcpu *vcpu)
{
int rc, cpuflags;
+ /*
+ * On s390 notifications for arriving pages will be delivered directly
+ * to the guest but the house keeping for completed pfaults is
+ * handled outside the worker.
+ */
+ kvm_check_async_pf_completion(vcpu);
+
memcpy(&vcpu->arch.sie_block->gg14, &vcpu->run->s.regs.gprs[14], 16);
if (need_resched())
@@ -758,8 +843,10 @@
rc = -EREMOTE;
} else if (current->thread.gmap_pfault) {
+ trace_kvm_s390_major_guest_pfault(vcpu);
current->thread.gmap_pfault = 0;
- if (kvm_arch_fault_in_sync(vcpu) >= 0)
+ if (kvm_arch_setup_async_pf(vcpu) ||
+ (kvm_arch_fault_in_sync(vcpu) >= 0))
rc = 0;
}