[PATCH v6 10/17] KVM: s390: pv: add mmu_notifier

Claudio Imbrenda
2021-12-03T16:59:09Z

Add an mmu_notifier for protected VMs. The callback function is
triggered when the mm is torn down, and will attempt to convert all
protected vCPUs to non-protected. This allows the mm teardown to use
the destroy page UVC instead of export.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
arch/s390/include/asm/kvm_host.h | 1 +
arch/s390/kvm/pv.c | 20 ++++++++++++++++++++
2 files changed, 21 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a604d51acfc8..8b288cff2a3a 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -921,6 +921,7 @@ struct kvm_s390_pv {
u64 guest_len;
unsigned long stor_base;
void *stor_var;
+ struct mmu_notifier mmu_notifier;
};

struct kvm_arch{
diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 59da54bd6b21..111f85158cce 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -195,6 +195,21 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
return -EIO;
}

+static void kvm_s390_pv_mmu_notifier_release(struct mmu_notifier *subscription,
+ struct mm_struct *mm)
+{
+ struct kvm *kvm = container_of(subscription, struct kvm, arch.pv.mmu_notifier);
+ u16 dummy;
+
+ mutex_lock(&kvm->lock);
+ kvm_s390_cpus_from_pv(kvm, &dummy, &dummy);
+ mutex_unlock(&kvm->lock);
+}
+
+static const struct mmu_notifier_ops kvm_s390_pv_mmu_notifier_ops = {
+ .release = kvm_s390_pv_mmu_notifier_release,
+};
+
int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
{
struct uv_cb_cgc uvcb = {
@@ -236,6 +251,11 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
return -EIO;
}
kvm->arch.gmap->guest_handle = uvcb.guest_handle;
+ /* Add the notifier only once. No races because we hold kvm->lock */
+ if (kvm->arch.pv.mmu_notifier.ops != &kvm_s390_pv_mmu_notifier_ops) {
+ kvm->arch.pv.mmu_notifier.ops = &kvm_s390_pv_mmu_notifier_ops;
+ mmu_notifier_register(&kvm->arch.pv.mmu_notifier, kvm->mm);
+ }
return 0;
}

--
2.31.1