Re: [PATCH v3 19/30] KVM: s390: pci: provide routines for enabling/disabling interpretation

Pierre Morel <pmorel@xxxxxxxxxxxxx> · Mon, 14 Feb 2022 14:22:50 +0100

On 2/4/22 22:15, Matthew Rosato wrote:
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             | 102 ++++++++++++++++++++++++++++++++
  arch/s390/pci/pci.c             |   3 +
  3 files changed, 109 insertions(+)

diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h
index ef10f9e46e37..422701d526dd 100644
--- a/arch/s390/include/asm/kvm_pci.h
+++ b/arch/s390/include/asm/kvm_pci.h
@@ -24,4 +24,8 @@ struct kvm_zdev {
  int kvm_s390_pci_dev_open(struct zpci_dev *zdev);
  void kvm_s390_pci_dev_release(struct zpci_dev *zdev);
  
+int kvm_s390_pci_interp_probe(struct zpci_dev *zdev);
+int kvm_s390_pci_interp_enable(struct zpci_dev *zdev);
+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 9b8390133e15..16bef3935284 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -12,7 +12,9 @@
  #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;
  
@@ -153,6 +155,106 @@ int kvm_s390_pci_aen_init(u8 nisc)
  	return rc;
  }
  
+int kvm_s390_pci_interp_probe(struct zpci_dev *zdev)
+{
+	/* Must have appropriate hardware facilities */
+	if (!sclp.has_zpci_lsi || !sclp.has_aisii || !sclp.has_aeni ||
+	    !sclp.has_aisi || !test_facility(69) || !test_facility(70) ||
+	    !test_facility(71) || !test_facility(72)) {
+		return -EINVAL;
+	}

I do not think we need to check STFLE facilities when the SCLP bit 
indicating the interpretation of a facility is installed the STFLE bit 
indicating the interpreted facility is also installed.


Otherwise, look good to me, with this change:
Reviewed-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>

+
+	/* Must have a KVM association registered */
+	if (!zdev->kzdev || !zdev->kzdev->kvm)
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_interp_probe);
+
+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;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_interp_enable);
+
+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;
+}
+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 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


--
Pierre Morel
IBM Lab Boeblingen






