[PATCH 4/4] vfio-pci/zdev: use a device region to retrieve zPCI information

Matthew Rosato
2020-09-19T15:29:04Z

Define a new configuration entry VFIO_PCI_ZDEV for VFIO/PCI.

When this s390-only feature is configured we initialize a new device
region, VFIO_REGION_SUBTYPE_IBM_ZPCI_CLP, to hold information provided
by the underlying hardware.

This patch is based on work previously done by Pierre Morel.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
drivers/vfio/pci/Kconfig | 13 ++
drivers/vfio/pci/Makefile | 1 +
drivers/vfio/pci/vfio_pci.c | 8 ++
drivers/vfio/pci/vfio_pci_private.h | 10 ++
drivers/vfio/pci/vfio_pci_zdev.c | 242 ++++++++++++++++++++++++++++++++++++
5 files changed, 274 insertions(+)
create mode 100644 drivers/vfio/pci/vfio_pci_zdev.c

diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
index ac3c1dd..07b4a35 100644
--- a/drivers/vfio/pci/Kconfig
+++ b/drivers/vfio/pci/Kconfig
@@ -45,3 +45,16 @@ config VFIO_PCI_NVLINK2
depends on VFIO_PCI && PPC_POWERNV
help
VFIO PCI support for P9 Witherspoon machine with NVIDIA V100 GPUs
+
+config VFIO_PCI_ZDEV
+ bool "VFIO PCI ZPCI device CLP support"
+ depends on VFIO_PCI && S390
+ default y
+ help
+ Enabling this options exposes a region containing hardware
+ configuration for zPCI devices. This enables userspace (e.g. QEMU)
+ to supply proper configuration values instead of hard-coded defaults
+ for zPCI devices passed through via VFIO on s390.
+
+ Say Y here.
+
diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
index f027f8a..781e080 100644
--- a/drivers/vfio/pci/Makefile
+++ b/drivers/vfio/pci/Makefile
@@ -3,5 +3,6 @@
vfio-pci-y := vfio_pci.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o
vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
vfio-pci-$(CONFIG_VFIO_PCI_NVLINK2) += vfio_pci_nvlink2.o
+vfio-pci-$(CONFIG_VFIO_PCI_ZDEV) += vfio_pci_zdev.o

obj-$(CONFIG_VFIO_PCI) += vfio-pci.o
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 1ab1f5c..cfb04d9 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -409,6 +409,14 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
}
}

+ if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV)) {
+ ret = vfio_pci_zdev_init(vdev);
+ if (ret && ret != -ENODEV) {
+ pci_warn(pdev, "Failed to setup zPCI CLP region\n");
+ goto disable_exit;
+ }
+ }
+
vfio_pci_probe_mmaps(vdev);

return 0;
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 61ca8ab..729af20 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -213,4 +213,14 @@ static inline int vfio_pci_ibm_npu2_init(struct vfio_pci_device *vdev)
return -ENODEV;
}
#endif
+
+#ifdef CONFIG_VFIO_PCI_ZDEV
+extern int vfio_pci_zdev_init(struct vfio_pci_device *vdev);
+#else
+static inline int vfio_pci_zdev_init(struct vfio_pci_device *vdev)
+{
+ return -ENODEV;
+}
+#endif
+
#endif /* VFIO_PCI_PRIVATE_H */
diff --git a/drivers/vfio/pci/vfio_pci_zdev.c b/drivers/vfio/pci/vfio_pci_zdev.c
new file mode 100644
index 0000000..9c7d659
--- /dev/null
+++ b/drivers/vfio/pci/vfio_pci_zdev.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * VFIO ZPCI devices support
+ *
+ * Copyright (C) IBM Corp. 2020. All rights reserved.
+ * Author(s): Pierre Morel <pmorel@linux.ibm.com>
+ * Matthew Rosato <mjrosato@linux.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+#include <linux/io.h>
+#include <linux/pci.h>
+#include <linux/uaccess.h>
+#include <linux/vfio.h>
+#include <linux/vfio_zdev.h>
+#include <asm/pci_clp.h>
+#include <asm/pci_io.h>
+
+#include "vfio_pci_private.h"
+
+static size_t vfio_pci_zdev_rw(struct vfio_pci_device *vdev,
+ char __user *buf, size_t count, loff_t *ppos,
+ bool iswrite)
+{
+ unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) - VFIO_PCI_NUM_REGIONS;
+ struct vfio_region_zpci_info *region = vdev->region[i].data;
+ loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
+
+ if ((!vdev->pdev->bus) || (!to_zpci(vdev->pdev)))
+ return -ENODEV;
+
+ if (pos >= vdev->region[i].size || iswrite)
+ return -EINVAL;
+
+ count = min(count, (size_t)(vdev->region[i].size - pos));
+ if (copy_to_user(buf, region + pos, count))
+ return -EFAULT;
+
+ return count;
+}
+
+static void vfio_pci_zdev_release(struct vfio_pci_device *vdev,
+ struct vfio_pci_region *region)
+{
+ kfree(region->data);
+}
+
+static const struct vfio_pci_regops vfio_pci_zdev_regops = {
+ .rw = vfio_pci_zdev_rw,
+ .release = vfio_pci_zdev_release,
+};
+
+static void vfio_pci_zdev_fill_hdr(struct vfio_region_zpci_info_hdr *hdr,
+ __u16 id, __u16 version, size_t offset,
+ size_t size)
+{
+ hdr->id = id;
+ hdr->version = version;
+ hdr->next = offset + size;
+}
+
+/*
+ * Add the Query PCI Function information to the device region.
+ *
+ * zdev - the zPCI device to get information from
+ * region - start of the vfio device region
+ * offset - location within region to place the data
+ *
+ * On return, provide the offset of the end of this CLP feature.
+ */
+static size_t vfio_pci_zdev_add_qpci(struct zpci_dev *zdev, void *region,
+ size_t offset)
+{
+ struct vfio_region_zpci_info_qpci *clp;
+
+ /* Jump to the CLP region via the offset */
+ clp = (struct vfio_region_zpci_info_qpci *) (region + offset);
+
+ /* Fill in the clp header */
+ vfio_pci_zdev_fill_hdr(&clp->hdr, VFIO_REGION_ZPCI_INFO_QPCI, 1,
+ offset, sizeof(*clp));
+
+ /* Fill in the CLP feature info */
+ clp->start_dma = zdev->start_dma;
+ clp->end_dma = zdev->end_dma;
+ clp->pchid = zdev->pchid;
+ clp->vfn = zdev->vfn;
+ clp->fmb_length = zdev->fmb_length;
+ clp->pft = zdev->pft;
+ clp->gid = zdev->pfgid;
+
+ /* Return offset to the end of this CLP feature */
+ return clp->hdr.next;
+}
+
+/*
+ * Add the Query PCI Function Group information to the device region.
+ *
+ * zdev - the zPCI device to get information from
+ * region - start of the vfio device region
+ * offset - location within region to place the data
+ *
+ * On return, provide the offset of the end of this CLP feature.
+ */
+static size_t vfio_pci_zdev_add_qpcifg(struct zpci_dev *zdev, void *region,
+ size_t offset)
+{
+ struct vfio_region_zpci_info_qpcifg *clp;
+
+ /* Jump to the CLP region via the offset */
+ clp = (struct vfio_region_zpci_info_qpcifg *) (region + offset);
+
+ /* Fill in the clp header */
+ vfio_pci_zdev_fill_hdr(&clp->hdr, VFIO_REGION_ZPCI_INFO_QPCIFG, 1,
+ offset, sizeof(*clp));
+
+ /* Fill in the CLP feature info */
+ clp->dasm = zdev->dma_mask;
+ clp->msi_addr = zdev->msi_addr;
+ clp->flags = VFIO_PCI_ZDEV_FLAGS_REFRESH;
+ clp->mui = zdev->fmb_update;
+ clp->noi = zdev->max_msi;
+ clp->maxstbl = ZPCI_MAX_WRITE_SIZE;
+ clp->version = zdev->version;
+
+ /* Return offset to the end of this CLP feature */
+ return clp->hdr.next;
+}
+
+/*
+ * Add the device utility string to the device region.
+ *
+ * zdev - the zPCI device to get information from
+ * region - start of the vfio device region
+ * offset - location within region to place the data
+ *
+ * On return, provide the offset of the end of this CLP feature.
+ */
+static size_t vfio_pci_zdev_add_util(struct zpci_dev *zdev, void *region,
+ size_t offset)
+{
+ struct vfio_region_zpci_info_util *clp;
+ size_t size = CLP_UTIL_STR_LEN;
+
+ /* Only add a utility string if one is available */
+ if (!zdev->util_avail)
+ return offset;
+
+ /* Jump to the CLP region via the offset */
+ clp = (struct vfio_region_zpci_info_util *) (region + offset);
+
+ /* Fill in the clp header */
+ vfio_pci_zdev_fill_hdr(&clp->hdr, VFIO_REGION_ZPCI_INFO_UTIL, 1,
+ offset, sizeof(*clp) + size);
+
+ /* Fill in the CLP feature info */
+ clp->size = size;
+ memcpy(clp->util_str, zdev->util_str, size);
+
+ /* Return offset to the end of this CLP feature */
+ return clp->hdr.next;
+}
+
+/*
+ * Add the function path string to the device region.
+ *
+ * zdev - the zPCI device to get information from
+ * region - start of the vfio device region
+ * offset - location within region to place the data
+ *
+ * On return, provide the offset of the end of this CLP feature.
+ */
+static size_t vfio_pci_zdev_add_pfip(struct zpci_dev *zdev, void *region,
+ size_t offset)
+{
+ struct vfio_region_zpci_info_pfip *clp;
+ size_t size = CLP_PFIP_NR_SEGMENTS;
+
+ /* Jump to the CLP region via the offset */
+ clp = (struct vfio_region_zpci_info_pfip *) (region + offset);
+
+ /* Fill in the clp header */
+ vfio_pci_zdev_fill_hdr(&clp->hdr, VFIO_REGION_ZPCI_INFO_PFIP, 1,
+ offset, sizeof(*clp) + size);
+
+ /* Fill in the CLP feature info */
+ clp->size = size;
+ memcpy(clp->pfip, zdev->pfip, size);
+
+ /* Return offset to the end of this CLP feature */
+ return clp->hdr.next;
+}
+
+int vfio_pci_zdev_init(struct vfio_pci_device *vdev)
+{
+ struct vfio_region_zpci_info *region;
+ struct zpci_dev *zdev;
+ size_t clp_offset;
+ int size;
+ int ret;
+
+ if (!vdev->pdev->bus)
+ return -ENODEV;
+
+ zdev = to_zpci(vdev->pdev);
+ if (!zdev)
+ return -ENODEV;
+
+ /* Calculate size needed for all supported CLP features */
+ size = sizeof(*region) +
+ sizeof(struct vfio_region_zpci_info_qpci) +
+ sizeof(struct vfio_region_zpci_info_qpcifg) +
+ (sizeof(struct vfio_region_zpci_info_util) + CLP_UTIL_STR_LEN) +
+ (sizeof(struct vfio_region_zpci_info_pfip) +
+ CLP_PFIP_NR_SEGMENTS);
+
+ region = kmalloc(size, GFP_KERNEL);
+ if (!region)
+ return -ENOMEM;
+
+ /* Fill in header */
+ region->argsz = size;
+ clp_offset = region->offset = sizeof(struct vfio_region_zpci_info);
+
+ /* Fill the supported CLP features */
+ clp_offset = vfio_pci_zdev_add_qpci(zdev, region, clp_offset);
+ clp_offset = vfio_pci_zdev_add_qpcifg(zdev, region, clp_offset);
+ clp_offset = vfio_pci_zdev_add_util(zdev, region, clp_offset);
+ clp_offset = vfio_pci_zdev_add_pfip(zdev, region, clp_offset);
+
+ ret = vfio_pci_register_dev_region(vdev,
+ PCI_VENDOR_ID_IBM | VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
+ VFIO_REGION_SUBTYPE_IBM_ZPCI_CLP, &vfio_pci_zdev_regops,
+ size, VFIO_REGION_INFO_FLAG_READ, region);
+ if (ret)
+ kfree(region);
+
+ return ret;
+}
--
1.8.3.1