linux-kernel - [PATCH v4 23/32] KVM: s390: pci: provide routines for enabling/disabling interpretation

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Date:   Mon, 14 Mar 2022 15:44:42 -0400
From:   Matthew Rosato <mjrosato@...ux.ibm.com>
To:     linux-s390@...r.kernel.org
Cc:     alex.williamson@...hat.com, cohuck@...hat.com,
        schnelle@...ux.ibm.com, farman@...ux.ibm.com, pmorel@...ux.ibm.com,
        borntraeger@...ux.ibm.com, hca@...ux.ibm.com, gor@...ux.ibm.com,
        gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
        svens@...ux.ibm.com, frankja@...ux.ibm.com, david@...hat.com,
        imbrenda@...ux.ibm.com, vneethv@...ux.ibm.com,
        oberpar@...ux.ibm.com, freude@...ux.ibm.com, thuth@...hat.com,
        pasic@...ux.ibm.com, joro@...tes.org, will@...nel.org,
        pbonzini@...hat.com, corbet@....net, jgg@...dia.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-doc@...r.kernel.org
Subject: [PATCH v4 23/32] KVM: s390: pci: provide routines for enabling/disabling interpretation

These routines will be wired into a kvm ioctl in order to respond to
requests to enable / disable a device for zPCI Load/Store intepretation.

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

Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
---
 arch/s390/kvm/pci.c | 86 +++++++++++++++++++++++++++++++++++++++++++++
 arch/s390/pci/pci.c |  3 ++
 2 files changed, 89 insertions(+)

diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index 28fe95f13c33..df50dd6114c3 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -13,7 +13,9 @@
 #include <asm/kvm_pci.h>
 #include <asm/pci.h>
 #include <asm/pci_insn.h>
+#include <asm/sclp.h>
 #include "pci.h"
+#include "kvm-s390.h"
 
 struct zpci_aift *aift;
 
@@ -170,6 +172,87 @@ int kvm_s390_pci_aen_init(u8 nisc)
 	return rc;
 }
 
+static int kvm_s390_pci_interp_enable(struct zpci_dev *zdev)
+{
+	u32 gisa;
+	int rc;
+
+	if (!zdev->kzdev || !zdev->kzdev->kvm)
+		return -EINVAL;
+
+	/*
+	 * 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.
+	 */
+	gisa = (u32)virt_to_phys(&zdev->kzdev->kvm->arch.sie_page2->gisa);
+	if (zdev->gisa != 0 && zdev->gisa != gisa)
+		return -EPERM;
+
+	if (zdev_enabled(zdev)) {
+		zdev->gisa = 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->gisa = gisa;
+
+	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,
+				virt_to_phys(zdev->dma_table));
+	if (rc)
+		goto err;
+
+	return rc;
+
+err:
+	zdev->gisa = 0;
+	return rc;
+}
+
+static int kvm_s390_pci_interp_disable(struct zpci_dev *zdev)
+{
+	int rc;
+
+	if (zdev->gisa == 0)
+		return -EINVAL;
+
+	/* Remove the host CLP guest designation */
+	zdev->gisa = 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,
+				virt_to_phys(zdev->dma_table));
+
+	return rc;
+}
+
 static int kvm_s390_pci_group_notifier(struct notifier_block *nb,
 				       unsigned long action, void *data)
 {
@@ -203,6 +286,9 @@ void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
 {
 	struct kvm_zdev *kzdev;
 
+	if (zdev->gisa != 0)
+		kvm_s390_pci_interp_disable(zdev, true);
+
 	kzdev = zdev->kzdev;
 	WARN_ON(kzdev->zdev != zdev);
 	zdev->kzdev = 0;
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index 13033717cd4e..5dbe49ec325e 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -147,6 +147,7 @@ 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)
@@ -727,6 +728,7 @@ 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)
 {
@@ -750,6 +752,7 @@ 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