KVM: s390: pci: add routines to start/stop interpretive execution

These routines will be invoked at the time an s390x vfio-pci device is
associated with a KVM (or when the association is removed), allowing
the zPCI device to enable or disable load/store intepretation mode;
this requires the host zPCI device to inform firmware of the unique
token (GISA designation) that is associated with the owning KVM.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Link: https://lore.kernel.org/r/20220606203325.110625-17-mjrosato@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

3 files changed, 182 insertions, 0 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index a66da3f66114..4758bb731199 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2790,6 +2790,14 @@ static void sca_dispose(struct kvm *kvm)
 	kvm->arch.sca = NULL;
 }
 
+void kvm_arch_free_vm(struct kvm *kvm)
+{
+	if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM))
+		kvm_s390_pci_clear_list(kvm);
+
+	__kvm_arch_free_vm(kvm);
+}
+
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 {
 	gfp_t alloc_flags = GFP_KERNEL_ACCOUNT;
@@ -2872,6 +2880,13 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 
 	kvm_s390_crypto_init(kvm);
 
+	if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
+		mutex_lock(&kvm->lock);
+		kvm_s390_pci_init_list(kvm);
+		kvm_s390_vcpu_pci_enable_interp(kvm);
+		mutex_unlock(&kvm->lock);
+	}
+
 	mutex_init(&kvm->arch.float_int.ais_lock);
 	spin_lock_init(&kvm->arch.float_int.lock);
 	for (i = 0; i < FIRQ_LIST_COUNT; i++)
diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index b232c8cbaa81..24211741deb0 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -12,7 +12,9 @@
 #include <asm/pci.h>
 #include <asm/pci_insn.h>
 #include <asm/pci_io.h>
+#include <asm/sclp.h>
 #include "pci.h"
+#include "kvm-s390.h"
 
 struct zpci_aift *aift;
 
@@ -423,6 +425,166 @@ static void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
 	kfree(kzdev);
 }
 
+
+/*
+ * Register device with the specified KVM. If interpetation facilities are
+ * available, enable them and let userspace indicate whether or not they will
+ * be used (specify SHM bit to disable).
+ */
+int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm)
+{
+	int rc;
+
+	if (!zdev)
+		return -EINVAL;
+
+	mutex_lock(&zdev->kzdev_lock);
+
+	if (zdev->kzdev || zdev->gisa != 0 || !kvm) {
+		mutex_unlock(&zdev->kzdev_lock);
+		return -EINVAL;
+	}
+
+	kvm_get_kvm(kvm);
+
+	mutex_lock(&kvm->lock);
+
+	rc = kvm_s390_pci_dev_open(zdev);
+	if (rc)
+		goto err;
+
+	/*
+	 * If interpretation facilities aren't available, add the device to
+	 * the kzdev list but don't enable for interpretation.
+	 */
+	if (!kvm_s390_pci_interp_allowed())
+		goto out;
+
+	/*
+	 * If this is the first request to use an interpreted device, make the
+	 * necessary vcpu changes
+	 */
+	if (!kvm->arch.use_zpci_interp)
+		kvm_s390_vcpu_pci_enable_interp(kvm);
+
+	if (zdev_enabled(zdev)) {
+		rc = zpci_disable_device(zdev);
+		if (rc)
+			goto err;
+	}
+
+	/*
+	 * Store information about the identity of the kvm guest allowed to
+	 * access this device via interpretation to be used by host CLP
+	 */
+	zdev->gisa = (u32)virt_to_phys(&kvm->arch.sie_page2->gisa);
+
+	rc = zpci_enable_device(zdev);
+	if (rc)
+		goto clear_gisa;
+
+	/* Re-register the IOMMU that was already created */
+	rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+				virt_to_phys(zdev->dma_table));
+	if (rc)
+		goto clear_gisa;
+
+out:
+	zdev->kzdev->kvm = kvm;
+
+	spin_lock(&kvm->arch.kzdev_list_lock);
+	list_add_tail(&zdev->kzdev->entry, &kvm->arch.kzdev_list);
+	spin_unlock(&kvm->arch.kzdev_list_lock);
+
+	mutex_unlock(&kvm->lock);
+	mutex_unlock(&zdev->kzdev_lock);
+	return 0;
+
+clear_gisa:
+	zdev->gisa = 0;
+err:
+	if (zdev->kzdev)
+		kvm_s390_pci_dev_release(zdev);
+	mutex_unlock(&kvm->lock);
+	mutex_unlock(&zdev->kzdev_lock);
+	kvm_put_kvm(kvm);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_register_kvm);
+
+void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev)
+{
+	struct kvm *kvm;
+
+	if (!zdev)
+		return;
+
+	mutex_lock(&zdev->kzdev_lock);
+
+	if (WARN_ON(!zdev->kzdev)) {
+		mutex_unlock(&zdev->kzdev_lock);
+		return;
+	}
+
+	kvm = zdev->kzdev->kvm;
+	mutex_lock(&kvm->lock);
+
+	/*
+	 * A 0 gisa means interpretation was never enabled, just remove the
+	 * device from the list.
+	 */
+	if (zdev->gisa == 0)
+		goto out;
+
+	/* Forwarding must be turned off before interpretation */
+	if (zdev->kzdev->fib.fmt0.aibv != 0)
+		kvm_s390_pci_aif_disable(zdev, true);
+
+	/* Remove the host CLP guest designation */
+	zdev->gisa = 0;
+
+	if (zdev_enabled(zdev)) {
+		if (zpci_disable_device(zdev))
+			goto out;
+	}
+
+	if (zpci_enable_device(zdev))
+		goto out;
+
+	/* Re-register the IOMMU that was already created */
+	zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+			   virt_to_phys(zdev->dma_table));
+
+out:
+	spin_lock(&kvm->arch.kzdev_list_lock);
+	list_del(&zdev->kzdev->entry);
+	spin_unlock(&kvm->arch.kzdev_list_lock);
+	kvm_s390_pci_dev_release(zdev);
+
+	mutex_unlock(&kvm->lock);
+	mutex_unlock(&zdev->kzdev_lock);
+
+	kvm_put_kvm(kvm);
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_unregister_kvm);
+
+void kvm_s390_pci_init_list(struct kvm *kvm)
+{
+	spin_lock_init(&kvm->arch.kzdev_list_lock);
+	INIT_LIST_HEAD(&kvm->arch.kzdev_list);
+}
+
+void kvm_s390_pci_clear_list(struct kvm *kvm)
+{
+	/*
+	 * This list should already be empty, either via vfio device closures
+	 * or kvm fd cleanup.
+	 */
+	spin_lock(&kvm->arch.kzdev_list_lock);
+	WARN_ON_ONCE(!list_empty(&kvm->arch.kzdev_list));
+	spin_unlock(&kvm->arch.kzdev_list_lock);
+}
+
 int kvm_s390_pci_init(void)
 {
 	aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h
index 9d091033fc02..fb2b91b76e0c 100644
--- a/arch/s390/kvm/pci.h
+++ b/arch/s390/kvm/pci.h
@@ -13,6 +13,7 @@
 #include <linux/kvm_host.h>
 #include <linux/pci.h>
 #include <linux/mutex.h>
+#include <linux/kvm.h>
 #include <linux/kvm_host.h>
 #include <asm/airq.h>
 #include <asm/cpu.h>
@@ -21,6 +22,7 @@ struct kvm_zdev {
 	struct zpci_dev *zdev;
 	struct kvm *kvm;
 	struct zpci_fib fib;
+	struct list_head entry;
 };
 
 struct zpci_gaite {
@@ -54,6 +56,9 @@ static inline struct kvm *kvm_s390_pci_si_to_kvm(struct zpci_aift *aift,
 int kvm_s390_pci_aen_init(u8 nisc);
 void kvm_s390_pci_aen_exit(void);
 
+void kvm_s390_pci_init_list(struct kvm *kvm);
+void kvm_s390_pci_clear_list(struct kvm *kvm);
+
 int kvm_s390_pci_init(void);
 void kvm_s390_pci_exit(void);