[PATCH v6 16/17] powerpc/vas: Implement a simple FTW driver
Sukadev Bhattiprolu
sukadev at linux.vnet.ibm.com
Wed Aug 9 09:07:01 AEST 2017
The Fast Thread Wake-up (FTW) driver provides user space applications an
interface to the Core-to-Core functionality in POWER9. The driver provides
the device node/ioctl API to applications and uses the external interfaces
to the VAS driver to interact with the VAS hardware.
A follow-on patch provides detailed description of the API for the driver.
Signed-off-by: Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>
---
MAINTAINERS | 1 +
arch/powerpc/platforms/powernv/Kconfig | 16 ++
arch/powerpc/platforms/powernv/Makefile | 1 +
arch/powerpc/platforms/powernv/nx-ftw.c | 486 ++++++++++++++++++++++++++++++++
4 files changed, 504 insertions(+)
create mode 100644 arch/powerpc/platforms/powernv/nx-ftw.c
diff --git a/MAINTAINERS b/MAINTAINERS
index c3f156c..a45c0c4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6431,6 +6431,7 @@ L: linuxppc-dev at lists.ozlabs.org
S: Supported
F: arch/powerpc/platforms/powernv/vas*
F: arch/powerpc/platforms/powernv/copy-paste.h
+F: arch/powerpc/platforms/powernv/nx-ftw*
F: arch/powerpc/include/asm/vas.h
F: arch/powerpc/include/uapi/asm/vas.h
diff --git a/arch/powerpc/platforms/powernv/Kconfig b/arch/powerpc/platforms/powernv/Kconfig
index f565454..67ea0ff 100644
--- a/arch/powerpc/platforms/powernv/Kconfig
+++ b/arch/powerpc/platforms/powernv/Kconfig
@@ -44,3 +44,19 @@ config PPC_VAS
VAS adapters are found in POWER9 based systems.
If unsure, say N.
+
+config PPC_FTW
+ bool "IBM Fast Thread-Wakeup (FTW)"
+ depends on PPC_VAS
+ default n
+ help
+ This enables support for IBM Fast Thread-Wakeup driver.
+
+ The FTW driver allows applications to utilize a low overhead
+ core-to-core wake up mechansim in the IBM Virtual Accelerator
+ Switchboard (VAS) to improve performance.
+
+ VAS adapters are found in POWER9 based systems and are required
+ for the FTW driver to be operational.
+
+ If unsure, say N.
diff --git a/arch/powerpc/platforms/powernv/Makefile b/arch/powerpc/platforms/powernv/Makefile
index e4db292..dc60046 100644
--- a/arch/powerpc/platforms/powernv/Makefile
+++ b/arch/powerpc/platforms/powernv/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_MEMORY_FAILURE) += opal-memory-errors.o
obj-$(CONFIG_TRACEPOINTS) += opal-tracepoints.o
obj-$(CONFIG_OPAL_PRD) += opal-prd.o
obj-$(CONFIG_PPC_VAS) += vas.o vas-window.o
+obj-$(CONFIG_PPC_FTW) += nx-ftw.o
diff --git a/arch/powerpc/platforms/powernv/nx-ftw.c b/arch/powerpc/platforms/powernv/nx-ftw.c
new file mode 100644
index 0000000..a0b6388
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/nx-ftw.c
@@ -0,0 +1,486 @@
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <asm/cputable.h>
+#include <linux/device.h>
+#include <linux/debugfs.h>
+#include <linux/cdev.h>
+#include <linux/mutex.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/bootmem.h>
+#include <asm/opal-api.h>
+#include <asm/opal.h>
+#include <asm/page.h>
+#include <asm/vas.h>
+#include <asm/reg.h>
+
+/*
+ * NX-FTW is a device driver used to provide user space access to the
+ * Core-to-Core aka Fast Thread Wakeup (FTW) functionality provided by
+ * the Virtual Accelerator Subsystem (VAS) in POWER9 systems. See also
+ * arch/powerpc/platforms/powernv/vas*.
+ *
+ * The driver creates the device node /dev/crypto/nx-ftw that can be
+ * used as follows:
+ *
+ * fd = open("/dev/crypto/nx-ftw", O_RDWR);
+ * rc = ioctl(fd, VAS_RX_WIN_OPEN, &rxattr);
+ * rc = ioctl(fd, VAS_TX_WIN_OPEN, &txattr);
+ * paste_addr = mmap(NULL, PAGE_SIZE, prot, MAP_SHARED, fd, 0ULL).
+ * vas_copy(&crb, 0, 1);
+ * vas_paste(paste_addr, 0, 1);
+ *
+ * where "vas_copy" and "vas_paste" are defined in copy-paste.h.
+ */
+
+static char *nxftw_dev_name = "nx-ftw";
+static atomic_t nxftw_instid = ATOMIC_INIT(0);
+static dev_t nxftw_devt;
+static struct dentry *nxftw_debugfs;
+static struct class *nxftw_dbgfs_class;
+
+/*
+ * Wrapper object for the nx-ftw device node - there is just one
+ * instance of this node for the whole system.
+ */
+struct nxftw_dev {
+ struct cdev cdev;
+ struct device *device;
+ char *name;
+ atomic_t refcount;
+} nxftw_device;
+
+/*
+ * One instance per open of a nx-ftw device. Each nxftw_instance is
+ * associated with a VAS window, after the caller issues VAS_RX_WIN_OPEN
+ * or VAS_TX_WIN_OPEN ioctl.
+ */
+struct nxftw_instance {
+ int instance;
+ bool tx_win;
+ struct vas_window *window;
+};
+
+#define VAS_DEFAULT_VAS_ID 0
+#define POWERNV_LPID 0 /* TODO: For VM/KVM guests? */
+
+static char *nxftw_devnode(struct device *dev, umode_t *mode)
+{
+ return kasprintf(GFP_KERNEL, "crypto/%s", dev_name(dev));
+}
+
+static int nxftw_open(struct inode *inode, struct file *fp)
+{
+ int minor;
+ struct nxftw_instance *nxti;
+
+ minor = MINOR(inode->i_rdev);
+
+ nxti = kzalloc(sizeof(*nxti), GFP_KERNEL);
+ if (!nxti)
+ return -ENOMEM;
+
+ nxti->instance = atomic_inc_return(&nxftw_instid);
+ nxti->window = NULL;
+
+ fp->private_data = nxti;
+ return 0;
+}
+
+static int validate_txwin_user_attr(struct vas_tx_win_open_attr *uattr)
+{
+ int i;
+
+ if (uattr->version != 1)
+ return -EINVAL;
+
+ if (uattr->flags & ~VAS_FLAGS_HIGH_PRI)
+ return -EINVAL;
+
+ if (uattr->reserved1 || uattr->reserved2)
+ return -EINVAL;
+
+ for (i = 0; i < sizeof(uattr->reserved3) / sizeof(uint64_t); i++) {
+ if (uattr->reserved3[i])
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static bool validate_rxwin_user_attr(struct vas_rx_win_open_attr *uattr)
+{
+ int i;
+
+ if (uattr->version != 1)
+ return -EINVAL;
+
+ for (i = 0; i < sizeof(uattr->reserved) / sizeof(uint64_t); i++) {
+ if (uattr->reserved[i])
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+#ifdef vas_debug
+static inline void dump_rx_win_attr(struct vas_rx_win_attr *attr)
+{
+ pr_err("NX-FTW: user %d, nx %d, fault %d, ntfy %d, intr %d early %d\n",
+ attr->user_win ? 1 : 0,
+ attr->nx_win ? 1 : 0,
+ attr->fault_win ? 1 : 0,
+ attr->notify_disable ? 1 : 0,
+ attr->intr_disable ? 1 : 0,
+ attr->notify_early ? 1 : 0);
+
+ pr_err("NX-FTW: rx_fifo %p, rx_fifo_size %d, max value 0x%x\n",
+ attr->rx_fifo, attr->rx_fifo_size,
+ VAS_RX_FIFO_SIZE_MAX);
+
+}
+#else
+static inline void dump_rx_win_attr(struct vas_rx_win_attr *attr)
+{
+}
+#endif
+
+static int nxftw_ioc_open_rx_window(struct file *fp, unsigned long arg)
+{
+ int rc;
+ struct vas_rx_win_open_attr uattr;
+ struct vas_rx_win_attr rxattr;
+ struct nxftw_instance *nxti = fp->private_data;
+ struct vas_window *win;
+
+ rc = copy_from_user(&uattr, (void *)arg, sizeof(uattr));
+ if (rc) {
+ pr_devel("%s(): copy_from_user() returns %d\n", __func__, rc);
+ return -EFAULT;
+ }
+
+ rc = validate_rxwin_user_attr(&uattr);
+ if (rc)
+ return rc;
+
+ memset(&rxattr, 0, sizeof(rxattr));
+
+ rxattr.lnotify_lpid = POWERNV_LPID;
+
+ /*
+ * Only caller can own the window for now. Not sure if there is need
+ * for process P1 to make P2 the owner of a window. If so, we need to
+ * find P2, make sure we have permissions, get a reference etc.
+ */
+ rxattr.lnotify_pid = mfspr(SPRN_PID);
+ rxattr.lnotify_tid = mfspr(SPRN_TIDR);
+ rxattr.rx_fifo = NULL;
+ rxattr.rx_fifo_size = 0;
+ rxattr.intr_disable = true;
+ rxattr.user_win = true;
+
+ dump_rx_win_attr(&rxattr);
+
+ /*
+ * TODO: Rather than the default vas id, choose an instance of VAS
+ * based on the chip the caller is running.
+ */
+ win = vas_rx_win_open(VAS_DEFAULT_VAS_ID, VAS_COP_TYPE_FTW, &rxattr);
+ if (IS_ERR(win)) {
+ pr_devel("%s() vas_rx_win_open() failed, %ld\n", __func__,
+ PTR_ERR(win));
+ return PTR_ERR(win);
+ }
+
+ nxti->window = win;
+ uattr.rx_win_handle = vas_win_id(win);
+
+ rc = copy_to_user((void *)arg, &uattr, sizeof(uattr));
+ if (rc) {
+ pr_devel("%s(): copy_to_user() failed, %d\n", __func__, rc);
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
+static int nxftw_ioc_open_tx_window(struct file *fp, unsigned long arg)
+{
+ int rc;
+ enum vas_cop_type cop;
+ struct vas_window *win;
+ struct vas_tx_win_open_attr uattr;
+ struct vas_tx_win_attr txattr;
+ struct nxftw_instance *nxti = fp->private_data;
+
+ rc = copy_from_user(&uattr, (void *)arg, sizeof(uattr));
+ if (rc) {
+ pr_devel("%s(): copy_from_user() failed, %d\n", __func__, rc);
+ return -EFAULT;
+ }
+
+ cop = VAS_COP_TYPE_FTW;
+
+ rc = validate_txwin_user_attr(&uattr);
+ if (rc)
+ return rc;
+
+ pr_devel("Pid %d: Opening txwin, cop %d, PIDR %ld\n",
+ task_pid_nr(current), cop, mfspr(SPRN_PID));
+
+ vas_init_tx_win_attr(&txattr, cop);
+
+ txattr.lpid = POWERNV_LPID;
+ txattr.pidr = mfspr(SPRN_PID);
+ txattr.pid = task_pid_nr(current);
+ txattr.user_win = true;
+ txattr.pswid = uattr.rx_win_handle;
+
+ win = vas_tx_win_open(VAS_DEFAULT_VAS_ID, cop, &txattr);
+ if (IS_ERR(win)) {
+ pr_devel("%s() vas_tx_win_open() failed, %ld\n", __func__,
+ PTR_ERR(win));
+ return PTR_ERR(win);
+ }
+ nxti->window = win;
+ nxti->tx_win = true;
+
+ return 0;
+}
+
+static int nxftw_release(struct inode *inode, struct file *fp)
+{
+ struct nxftw_instance *nxti;
+
+ nxti = fp->private_data;
+
+ vas_win_close(nxti->window);
+ nxti->window = NULL;
+
+ kfree(nxti);
+ fp->private_data = NULL;
+ atomic_dec(&nxftw_instid);
+
+ return 0;
+}
+
+static ssize_t nxftw_write(struct file *fp, const char __user *buf,
+ size_t len, loff_t *offsetp)
+{
+ return -ENOTSUPP;
+}
+
+static ssize_t nxftw_read(struct file *fp, char __user *buf, size_t len,
+ loff_t *offsetp)
+{
+ return -ENOTSUPP;
+}
+
+static int nxftw_vma_fault(struct vm_fault *vmf)
+{
+ u64 offset;
+ unsigned long vaddr;
+ uint64_t pbaddr_start;
+ struct nxftw_instance *nxti;
+ struct vm_area_struct *vma = vmf->vma;
+
+ nxti = vma->vm_private_data;
+ offset = vmf->pgoff << PAGE_SHIFT;
+ vaddr = (unsigned long)vmf->address;
+
+ pbaddr_start = vas_win_paste_addr(nxti->window);
+
+ pr_devel("%s() instance %d, pbaddr 0x%llx, vaddr 0x%lx,"
+ "offset %llx, pgoff 0x%lx, vma-start 0x%zx,"
+ "size %zd\n", __func__, nxti->instance,
+ pbaddr_start, vaddr, offset, vmf->pgoff,
+ vma->vm_start, vma->vm_end-vma->vm_start);
+
+ vm_insert_pfn(vma, vaddr, (pbaddr_start + offset) >> PAGE_SHIFT);
+
+ return VM_FAULT_NOPAGE;
+}
+
+const struct vm_operations_struct nxftw_vm_ops = {
+ .fault = nxftw_vma_fault,
+};
+
+static int nxftw_mmap(struct file *fp, struct vm_area_struct *vma)
+{
+ struct nxftw_instance *nxti = fp->private_data;
+
+ if ((vma->vm_end - vma->vm_start) > PAGE_SIZE) {
+ pr_devel("%s(): size 0x%zx, PAGE_SIZE 0x%zx\n", __func__,
+ (vma->vm_end - vma->vm_start), PAGE_SIZE);
+ return -EINVAL;
+ }
+
+ /* Ensure instance has an open send window */
+ if (!nxti->window || !nxti->tx_win) {
+ pr_devel("%s(): No send window open?\n", __func__);
+ return -EINVAL;
+ }
+
+ /* flags, page_prot from cxl_mmap(), except we want cachable */
+ vma->vm_flags |= VM_IO | VM_PFNMAP;
+ vma->vm_page_prot = pgprot_cached(vma->vm_page_prot);
+
+ vma->vm_ops = &nxftw_vm_ops;
+ vma->vm_private_data = nxti;
+
+ return 0;
+}
+
+static long nxftw_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
+{
+ struct nxftw_instance *nxti;
+
+ nxti = fp->private_data;
+
+ pr_devel("%s() cmd 0x%x, TX_WIN_OPEN 0x%lx\n", __func__, cmd,
+ VAS_TX_WIN_OPEN);
+ switch (cmd) {
+
+ case VAS_TX_WIN_OPEN:
+ return nxftw_ioc_open_tx_window(fp, arg);
+
+ case VAS_RX_WIN_OPEN:
+ return nxftw_ioc_open_rx_window(fp, arg);
+
+ default:
+ return -EINVAL;
+ }
+}
+
+const struct file_operations nxftw_fops = {
+ .owner = THIS_MODULE,
+ .open = nxftw_open,
+ .release = nxftw_release,
+ .read = nxftw_read,
+ .write = nxftw_write,
+ .mmap = nxftw_mmap,
+ .unlocked_ioctl = nxftw_ioctl,
+};
+
+
+int nxftw_file_init(void)
+{
+ int rc;
+ dev_t devno;
+
+ rc = alloc_chrdev_region(&nxftw_devt, 1, 1, "nx-ftw");
+ if (rc) {
+ pr_err("Unable to allocate nxftw major number: %i\n", rc);
+ return rc;
+ }
+
+ pr_devel("NX-FTW device allocated, dev [%i,%i]\n", MAJOR(nxftw_devt),
+ MINOR(nxftw_devt));
+
+ nxftw_dbgfs_class = class_create(THIS_MODULE, "nxftw");
+ if (IS_ERR(nxftw_dbgfs_class)) {
+ pr_err("Unable to create NX-FTW class\n");
+ rc = PTR_ERR(nxftw_dbgfs_class);
+ goto err;
+ }
+ nxftw_dbgfs_class->devnode = nxftw_devnode;
+
+ cdev_init(&nxftw_device.cdev, &nxftw_fops);
+
+ devno = MKDEV(MAJOR(nxftw_devt), 0);
+ if (cdev_add(&nxftw_device.cdev, devno, 1)) {
+ pr_err("NX-FTW: cdev_add() failed\n");
+ goto err;
+ }
+
+ nxftw_device.device = device_create(nxftw_dbgfs_class, NULL,
+ devno, NULL, nxftw_dev_name, MINOR(devno));
+ if (IS_ERR(nxftw_device.device)) {
+ pr_err("Unable to create nxftw-%d\n", MINOR(devno));
+ goto err;
+ }
+
+ pr_devel("%s: Added dev [%d,%d]\n", __func__, MAJOR(devno),
+ MINOR(devno));
+ return 0;
+
+err:
+ unregister_chrdev_region(nxftw_devt, 1);
+ return rc;
+}
+
+void nxftw_file_exit(void)
+{
+ dev_t devno;
+
+ pr_devel("NX-FTW: %s entered\n", __func__);
+
+ cdev_del(&nxftw_device.cdev);
+ devno = MKDEV(MAJOR(nxftw_devt), MINOR(nxftw_devt));
+ device_destroy(nxftw_dbgfs_class, devno);
+
+ class_destroy(nxftw_dbgfs_class);
+ unregister_chrdev_region(nxftw_devt, 1);
+}
+
+
+/*
+ * Create a debugfs entry. Not sure what for yet, though
+ */
+int __init nxftw_debugfs_init(void)
+{
+ struct dentry *ent;
+
+ ent = debugfs_create_dir("nxftw", NULL);
+ if (IS_ERR(ent)) {
+ pr_devel("nxftw: %s(): error creating dbgfs dir\n", __func__);
+ return PTR_ERR(ent);
+ }
+ nxftw_debugfs = ent;
+
+ return 0;
+}
+
+void nxftw_debugfs_exit(void)
+{
+ debugfs_remove_recursive(nxftw_debugfs);
+}
+
+int __init nxftw_init(void)
+{
+ int rc;
+
+ rc = nxftw_file_init();
+ if (rc)
+ return rc;
+
+ rc = nxftw_debugfs_init();
+ if (rc)
+ goto free_file;
+
+ pr_err("NX-FTW Device initialized\n");
+
+ return 0;
+
+free_file:
+ nxftw_file_exit();
+ return rc;
+}
+
+void __init nxftw_exit(void)
+{
+ pr_devel("NX-FTW Device exiting\n");
+ nxftw_debugfs_exit();
+ nxftw_file_exit();
+}
+
+module_init(nxftw_init);
+module_exit(nxftw_exit);
+
+MODULE_DESCRIPTION("IBM NX Fast Thread Wakeup Device");
+MODULE_AUTHOR("Sukadev Bhattiprolu <sukadev at linux.vnet.ibm.com>");
+MODULE_LICENSE("GPL");
--
2.7.4
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