[PATCH 20/32] KVM: s390: pci: provide routines for enabling/disabling interpretation

[Matthew Rosato <mjrosato@xxxxxxxxxxxxx>]

These routines will be wired into the vfio_pci_zdev ioctl handlers to
respond to requests to enable / disable a device for zPCI Load/Store
interpretation.

The first time such a request is received, enable the necessary facilities
for the guest.

Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
---
 arch/s390/include/asm/kvm_pci.h |  4 ++
 arch/s390/kvm/pci.c             | 91 +++++++++++++++++++++++++++++++++
 arch/s390/pci/pci.c             |  3 ++
 3 files changed, 98 insertions(+)

diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
index 3e491a39704c..5d6283acb54c 100644
--- a/arch/s390/include/asm/kvm_pci.h
+++ b/arch/s390/include/asm/kvm_pci.h
@@ -26,4 +26,8 @@ extern int kvm_s390_pci_dev_open(struct zpci_dev *zdev);
 extern void kvm_s390_pci_dev_release(struct zpci_dev *zdev);
 extern int kvm_s390_pci_attach_kvm(struct zpci_dev *zdev, struct kvm *kvm);
 
+extern int kvm_s390_pci_interp_probe(struct zpci_dev *zdev);
+extern int kvm_s390_pci_interp_enable(struct zpci_dev *zdev);
+extern int kvm_s390_pci_interp_disable(struct zpci_dev *zdev);
+
 #endif /* ASM_KVM_PCI_H */
diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index f0e5386ff943..57cbe3827ea6 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -10,7 +10,9 @@
 #include <linux/kvm_host.h>
 #include <linux/pci.h>
 #include <asm/kvm_pci.h>
+#include <asm/sclp.h>
 #include "pci.h"
+#include "kvm-s390.h"
 
 static struct zpci_aift aift;
 
@@ -118,6 +120,95 @@ int kvm_s390_pci_aen_init(u8 nisc)
 	return rc;
 }
 
+int kvm_s390_pci_interp_probe(struct zpci_dev *zdev)
+{
+	if (!(sclp.has_zpci_interp && test_facility(69)))
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_interp_probe);
+
+int kvm_s390_pci_interp_enable(struct zpci_dev *zdev)
+{
+	u32 gd;
+	int rc;
+
+	/*
+	 * If this is the first request to use an interpreted device, make the
+	 * necessary vcpu changes
+	 */
+	if (!zdev->kzdev->kvm->arch.use_zpci_interp)
+		kvm_s390_vcpu_pci_enable_interp(zdev->kzdev->kvm);
+
+	/*
+	 * In the event of a system reset in userspace, the GISA designation
+	 * may still be assigned because the device is still enabled.
+	 * Verify it's the same guest before proceeding.
+	 */
+	gd = (u32)(u64)&zdev->kzdev->kvm->arch.sie_page2->gisa;
+	if (zdev->gd != 0 && zdev->gd != gd)
+		return -EPERM;
+
+	if (zdev_enabled(zdev)) {
+		zdev->gd = 0;
+		rc = zpci_disable_device(zdev);
+		if (rc)
+			return rc;
+	}
+
+	/*
+	 * Store information about the identity of the kvm guest allowed to
+	 * access this device via interpretation to be used by host CLP
+	 */
+	zdev->gd = gd;
+
+	rc = zpci_enable_device(zdev);
+	if (rc)
+		goto err;
+
+	/* Re-register the IOMMU that was already created */
+	rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+				(u64)zdev->dma_table);
+	if (rc)
+		goto err;
+
+	return rc;
+
+err:
+	zdev->gd = 0;
+	return rc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_interp_enable);
+
+int kvm_s390_pci_interp_disable(struct zpci_dev *zdev)
+{
+	int rc;
+
+	if (zdev->gd == 0)
+		return -EINVAL;
+
+	/* Remove the host CLP guest designation */
+	zdev->gd = 0;
+
+	if (zdev_enabled(zdev)) {
+		rc = zpci_disable_device(zdev);
+		if (rc)
+			return rc;
+	}
+
+	rc = zpci_enable_device(zdev);
+	if (rc)
+		return rc;
+
+	/* Re-register the IOMMU that was already created */
+	rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+				(u64)zdev->dma_table);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_interp_disable);
+
 int kvm_s390_pci_dev_open(struct zpci_dev *zdev)
 {
 	struct kvm_zdev *kzdev;
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 175854c861cd..0eac84387f3c 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -141,6 +141,7 @@ int zpci_register_ioat(struct zpci_dev *zdev, u8 dmaas,
 		zpci_dbg(3, "reg ioat fid:%x, cc:%d, status:%d\n", zdev->fid, cc, status);
 	return cc;
 }
+EXPORT_SYMBOL_GPL(zpci_register_ioat);
 
 /* Modify PCI: Unregister I/O address translation parameters */
 int zpci_unregister_ioat(struct zpci_dev *zdev, u8 dmaas)
@@ -740,6 +741,7 @@ int zpci_enable_device(struct zpci_dev *zdev)
 		zpci_update_fh(zdev, fh);
 	return rc;
 }
+EXPORT_SYMBOL_GPL(zpci_enable_device);
 
 int zpci_disable_device(struct zpci_dev *zdev)
 {
@@ -763,6 +765,7 @@ int zpci_disable_device(struct zpci_dev *zdev)
 	}
 	return rc;
 }
+EXPORT_SYMBOL_GPL(zpci_disable_device);
 
 /**
  * zpci_hot_reset_device - perform a reset of the given zPCI function
-- 
2.27.0