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-rw-r--r--arch/powerpc/platforms/book3s/vas-api.c634
1 files changed, 634 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
new file mode 100644
index 000000000..92e60cb31
--- /dev/null
+++ b/arch/powerpc/platforms/book3s/vas-api.c
@@ -0,0 +1,634 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * VAS user space API for its accelerators (Only NX-GZIP is supported now)
+ * Copyright (C) 2019 Haren Myneni, IBM Corp
+ */
+
+#define pr_fmt(fmt) "vas-api: " fmt
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/kthread.h>
+#include <linux/sched/signal.h>
+#include <linux/mmu_context.h>
+#include <linux/io.h>
+#include <asm/vas.h>
+#include <uapi/asm/vas-api.h>
+
+/*
+ * The driver creates the device node that can be used as follows:
+ * For NX-GZIP
+ *
+ * fd = open("/dev/crypto/nx-gzip", O_RDWR);
+ * rc = ioctl(fd, VAS_TX_WIN_OPEN, &attr);
+ * paste_addr = mmap(NULL, PAGE_SIZE, prot, MAP_SHARED, fd, 0ULL).
+ * vas_copy(&crb, 0, 1);
+ * vas_paste(paste_addr, 0, 1);
+ * close(fd) or exit process to close window.
+ *
+ * where "vas_copy" and "vas_paste" are defined in copy-paste.h.
+ * copy/paste returns to the user space directly. So refer NX hardware
+ * documentation for exact copy/paste usage and completion / error
+ * conditions.
+ */
+
+/*
+ * Wrapper object for the nx-gzip device - there is just one instance of
+ * this node for the whole system.
+ */
+static struct coproc_dev {
+ struct cdev cdev;
+ struct device *device;
+ char *name;
+ dev_t devt;
+ struct class *class;
+ enum vas_cop_type cop_type;
+ const struct vas_user_win_ops *vops;
+} coproc_device;
+
+struct coproc_instance {
+ struct coproc_dev *coproc;
+ struct vas_window *txwin;
+};
+
+static char *coproc_devnode(struct device *dev, umode_t *mode)
+{
+ return kasprintf(GFP_KERNEL, "crypto/%s", dev_name(dev));
+}
+
+/*
+ * Take reference to pid and mm
+ */
+int get_vas_user_win_ref(struct vas_user_win_ref *task_ref)
+{
+ /*
+ * Window opened by a child thread may not be closed when
+ * it exits. So take reference to its pid and release it
+ * when the window is free by parent thread.
+ * Acquire a reference to the task's pid to make sure
+ * pid will not be re-used - needed only for multithread
+ * applications.
+ */
+ task_ref->pid = get_task_pid(current, PIDTYPE_PID);
+ /*
+ * Acquire a reference to the task's mm.
+ */
+ task_ref->mm = get_task_mm(current);
+ if (!task_ref->mm) {
+ put_pid(task_ref->pid);
+ pr_err("pid(%d): mm_struct is not found\n",
+ current->pid);
+ return -EPERM;
+ }
+
+ mmgrab(task_ref->mm);
+ mmput(task_ref->mm);
+ /*
+ * Process closes window during exit. In the case of
+ * multithread application, the child thread can open
+ * window and can exit without closing it. So takes tgid
+ * reference until window closed to make sure tgid is not
+ * reused.
+ */
+ task_ref->tgid = find_get_pid(task_tgid_vnr(current));
+
+ return 0;
+}
+
+/*
+ * Successful return must release the task reference with
+ * put_task_struct
+ */
+static bool ref_get_pid_and_task(struct vas_user_win_ref *task_ref,
+ struct task_struct **tskp, struct pid **pidp)
+{
+ struct task_struct *tsk;
+ struct pid *pid;
+
+ pid = task_ref->pid;
+ tsk = get_pid_task(pid, PIDTYPE_PID);
+ if (!tsk) {
+ pid = task_ref->tgid;
+ tsk = get_pid_task(pid, PIDTYPE_PID);
+ /*
+ * Parent thread (tgid) will be closing window when it
+ * exits. So should not get here.
+ */
+ if (WARN_ON_ONCE(!tsk))
+ return false;
+ }
+
+ /* Return if the task is exiting. */
+ if (tsk->flags & PF_EXITING) {
+ put_task_struct(tsk);
+ return false;
+ }
+
+ *tskp = tsk;
+ *pidp = pid;
+
+ return true;
+}
+
+/*
+ * Update the CSB to indicate a translation error.
+ *
+ * User space will be polling on CSB after the request is issued.
+ * If NX can handle the request without any issues, it updates CSB.
+ * Whereas if NX encounters page fault, the kernel will handle the
+ * fault and update CSB with translation error.
+ *
+ * If we are unable to update the CSB means copy_to_user failed due to
+ * invalid csb_addr, send a signal to the process.
+ */
+void vas_update_csb(struct coprocessor_request_block *crb,
+ struct vas_user_win_ref *task_ref)
+{
+ struct coprocessor_status_block csb;
+ struct kernel_siginfo info;
+ struct task_struct *tsk;
+ void __user *csb_addr;
+ struct pid *pid;
+ int rc;
+
+ /*
+ * NX user space windows can not be opened for task->mm=NULL
+ * and faults will not be generated for kernel requests.
+ */
+ if (WARN_ON_ONCE(!task_ref->mm))
+ return;
+
+ csb_addr = (void __user *)be64_to_cpu(crb->csb_addr);
+
+ memset(&csb, 0, sizeof(csb));
+ csb.cc = CSB_CC_FAULT_ADDRESS;
+ csb.ce = CSB_CE_TERMINATION;
+ csb.cs = 0;
+ csb.count = 0;
+
+ /*
+ * NX operates and returns in BE format as defined CRB struct.
+ * So saves fault_storage_addr in BE as NX pastes in FIFO and
+ * expects user space to convert to CPU format.
+ */
+ csb.address = crb->stamp.nx.fault_storage_addr;
+ csb.flags = 0;
+
+ /*
+ * Process closes send window after all pending NX requests are
+ * completed. In multi-thread applications, a child thread can
+ * open a window and can exit without closing it. May be some
+ * requests are pending or this window can be used by other
+ * threads later. We should handle faults if NX encounters
+ * pages faults on these requests. Update CSB with translation
+ * error and fault address. If csb_addr passed by user space is
+ * invalid, send SEGV signal to pid saved in window. If the
+ * child thread is not running, send the signal to tgid.
+ * Parent thread (tgid) will close this window upon its exit.
+ *
+ * pid and mm references are taken when window is opened by
+ * process (pid). So tgid is used only when child thread opens
+ * a window and exits without closing it.
+ */
+
+ if (!ref_get_pid_and_task(task_ref, &tsk, &pid))
+ return;
+
+ kthread_use_mm(task_ref->mm);
+ rc = copy_to_user(csb_addr, &csb, sizeof(csb));
+ /*
+ * User space polls on csb.flags (first byte). So add barrier
+ * then copy first byte with csb flags update.
+ */
+ if (!rc) {
+ csb.flags = CSB_V;
+ /* Make sure update to csb.flags is visible now */
+ smp_mb();
+ rc = copy_to_user(csb_addr, &csb, sizeof(u8));
+ }
+ kthread_unuse_mm(task_ref->mm);
+ put_task_struct(tsk);
+
+ /* Success */
+ if (!rc)
+ return;
+
+
+ pr_debug("Invalid CSB address 0x%p signalling pid(%d)\n",
+ csb_addr, pid_vnr(pid));
+
+ clear_siginfo(&info);
+ info.si_signo = SIGSEGV;
+ info.si_errno = EFAULT;
+ info.si_code = SEGV_MAPERR;
+ info.si_addr = csb_addr;
+ /*
+ * process will be polling on csb.flags after request is sent to
+ * NX. So generally CSB update should not fail except when an
+ * application passes invalid csb_addr. So an error message will
+ * be displayed and leave it to user space whether to ignore or
+ * handle this signal.
+ */
+ rcu_read_lock();
+ rc = kill_pid_info(SIGSEGV, &info, pid);
+ rcu_read_unlock();
+
+ pr_devel("pid %d kill_proc_info() rc %d\n", pid_vnr(pid), rc);
+}
+
+void vas_dump_crb(struct coprocessor_request_block *crb)
+{
+ struct data_descriptor_entry *dde;
+ struct nx_fault_stamp *nx;
+
+ dde = &crb->source;
+ pr_devel("SrcDDE: addr 0x%llx, len %d, count %d, idx %d, flags %d\n",
+ be64_to_cpu(dde->address), be32_to_cpu(dde->length),
+ dde->count, dde->index, dde->flags);
+
+ dde = &crb->target;
+ pr_devel("TgtDDE: addr 0x%llx, len %d, count %d, idx %d, flags %d\n",
+ be64_to_cpu(dde->address), be32_to_cpu(dde->length),
+ dde->count, dde->index, dde->flags);
+
+ nx = &crb->stamp.nx;
+ pr_devel("NX Stamp: PSWID 0x%x, FSA 0x%llx, flags 0x%x, FS 0x%x\n",
+ be32_to_cpu(nx->pswid),
+ be64_to_cpu(crb->stamp.nx.fault_storage_addr),
+ nx->flags, nx->fault_status);
+}
+
+static int coproc_open(struct inode *inode, struct file *fp)
+{
+ struct coproc_instance *cp_inst;
+
+ cp_inst = kzalloc(sizeof(*cp_inst), GFP_KERNEL);
+ if (!cp_inst)
+ return -ENOMEM;
+
+ cp_inst->coproc = container_of(inode->i_cdev, struct coproc_dev,
+ cdev);
+ fp->private_data = cp_inst;
+
+ return 0;
+}
+
+static int coproc_ioc_tx_win_open(struct file *fp, unsigned long arg)
+{
+ void __user *uptr = (void __user *)arg;
+ struct vas_tx_win_open_attr uattr;
+ struct coproc_instance *cp_inst;
+ struct vas_window *txwin;
+ int rc;
+
+ cp_inst = fp->private_data;
+
+ /*
+ * One window for file descriptor
+ */
+ if (cp_inst->txwin)
+ return -EEXIST;
+
+ rc = copy_from_user(&uattr, uptr, sizeof(uattr));
+ if (rc) {
+ pr_err("copy_from_user() returns %d\n", rc);
+ return -EFAULT;
+ }
+
+ if (uattr.version != 1) {
+ pr_err("Invalid window open API version\n");
+ return -EINVAL;
+ }
+
+ if (!cp_inst->coproc->vops || !cp_inst->coproc->vops->open_win) {
+ pr_err("VAS API is not registered\n");
+ return -EACCES;
+ }
+
+ txwin = cp_inst->coproc->vops->open_win(uattr.vas_id, uattr.flags,
+ cp_inst->coproc->cop_type);
+ if (IS_ERR(txwin)) {
+ pr_err_ratelimited("VAS window open failed rc=%ld\n",
+ PTR_ERR(txwin));
+ return PTR_ERR(txwin);
+ }
+
+ mutex_init(&txwin->task_ref.mmap_mutex);
+ cp_inst->txwin = txwin;
+
+ return 0;
+}
+
+static int coproc_release(struct inode *inode, struct file *fp)
+{
+ struct coproc_instance *cp_inst = fp->private_data;
+ int rc;
+
+ if (cp_inst->txwin) {
+ if (cp_inst->coproc->vops &&
+ cp_inst->coproc->vops->close_win) {
+ rc = cp_inst->coproc->vops->close_win(cp_inst->txwin);
+ if (rc)
+ return rc;
+ }
+ cp_inst->txwin = NULL;
+ }
+
+ kfree(cp_inst);
+ fp->private_data = NULL;
+
+ /*
+ * We don't know here if user has other receive windows
+ * open, so we can't really call clear_thread_tidr().
+ * So, once the process calls set_thread_tidr(), the
+ * TIDR value sticks around until process exits, resulting
+ * in an extra copy in restore_sprs().
+ */
+
+ return 0;
+}
+
+/*
+ * If the executed instruction that caused the fault was a paste, then
+ * clear regs CR0[EQ], advance NIP, and return 0. Else return error code.
+ */
+static int do_fail_paste(void)
+{
+ struct pt_regs *regs = current->thread.regs;
+ u32 instword;
+
+ if (WARN_ON_ONCE(!regs))
+ return -EINVAL;
+
+ if (WARN_ON_ONCE(!user_mode(regs)))
+ return -EINVAL;
+
+ /*
+ * If we couldn't translate the instruction, the driver should
+ * return success without handling the fault, it will be retried
+ * or the instruction fetch will fault.
+ */
+ if (get_user(instword, (u32 __user *)(regs->nip)))
+ return -EAGAIN;
+
+ /*
+ * Not a paste instruction, driver may fail the fault.
+ */
+ if ((instword & PPC_INST_PASTE_MASK) != PPC_INST_PASTE)
+ return -ENOENT;
+
+ regs->ccr &= ~0xe0000000; /* Clear CR0[0-2] to fail paste */
+ regs_add_return_ip(regs, 4); /* Emulate the paste */
+
+ return 0;
+}
+
+/*
+ * This fault handler is invoked when the core generates page fault on
+ * the paste address. Happens if the kernel closes window in hypervisor
+ * (on pseries) due to lost credit or the paste address is not mapped.
+ */
+static vm_fault_t vas_mmap_fault(struct vm_fault *vmf)
+{
+ struct vm_area_struct *vma = vmf->vma;
+ struct file *fp = vma->vm_file;
+ struct coproc_instance *cp_inst = fp->private_data;
+ struct vas_window *txwin;
+ vm_fault_t fault;
+ u64 paste_addr;
+ int ret;
+
+ /*
+ * window is not opened. Shouldn't expect this error.
+ */
+ if (!cp_inst || !cp_inst->txwin) {
+ pr_err("Unexpected fault on paste address with TX window closed\n");
+ return VM_FAULT_SIGBUS;
+ }
+
+ txwin = cp_inst->txwin;
+ /*
+ * When the LPAR lost credits due to core removal or during
+ * migration, invalidate the existing mapping for the current
+ * paste addresses and set windows in-active (zap_page_range in
+ * reconfig_close_windows()).
+ * New mapping will be done later after migration or new credits
+ * available. So continue to receive faults if the user space
+ * issue NX request.
+ */
+ if (txwin->task_ref.vma != vmf->vma) {
+ pr_err("No previous mapping with paste address\n");
+ return VM_FAULT_SIGBUS;
+ }
+
+ mutex_lock(&txwin->task_ref.mmap_mutex);
+ /*
+ * The window may be inactive due to lost credit (Ex: core
+ * removal with DLPAR). If the window is active again when
+ * the credit is available, map the new paste address at the
+ * window virtual address.
+ */
+ if (txwin->status == VAS_WIN_ACTIVE) {
+ paste_addr = cp_inst->coproc->vops->paste_addr(txwin);
+ if (paste_addr) {
+ fault = vmf_insert_pfn(vma, vma->vm_start,
+ (paste_addr >> PAGE_SHIFT));
+ mutex_unlock(&txwin->task_ref.mmap_mutex);
+ return fault;
+ }
+ }
+ mutex_unlock(&txwin->task_ref.mmap_mutex);
+
+ /*
+ * Received this fault due to closing the actual window.
+ * It can happen during migration or lost credits.
+ * Since no mapping, return the paste instruction failure
+ * to the user space.
+ */
+ ret = do_fail_paste();
+ /*
+ * The user space can retry several times until success (needed
+ * for migration) or should fallback to SW compression or
+ * manage with the existing open windows if available.
+ * Looking at sysfs interface, it can determine whether these
+ * failures are coming during migration or core removal:
+ * nr_used_credits > nr_total_credits when lost credits
+ */
+ if (!ret || (ret == -EAGAIN))
+ return VM_FAULT_NOPAGE;
+
+ return VM_FAULT_SIGBUS;
+}
+
+static const struct vm_operations_struct vas_vm_ops = {
+ .fault = vas_mmap_fault,
+};
+
+static int coproc_mmap(struct file *fp, struct vm_area_struct *vma)
+{
+ struct coproc_instance *cp_inst = fp->private_data;
+ struct vas_window *txwin;
+ unsigned long pfn;
+ u64 paste_addr;
+ pgprot_t prot;
+ int rc;
+
+ txwin = cp_inst->txwin;
+
+ if ((vma->vm_end - vma->vm_start) > PAGE_SIZE) {
+ pr_debug("size 0x%zx, PAGE_SIZE 0x%zx\n",
+ (vma->vm_end - vma->vm_start), PAGE_SIZE);
+ return -EINVAL;
+ }
+
+ /* Ensure instance has an open send window */
+ if (!txwin) {
+ pr_err("No send window open?\n");
+ return -EINVAL;
+ }
+
+ if (!cp_inst->coproc->vops || !cp_inst->coproc->vops->paste_addr) {
+ pr_err("VAS API is not registered\n");
+ return -EACCES;
+ }
+
+ /*
+ * The initial mmap is done after the window is opened
+ * with ioctl. But before mmap(), this window can be closed in
+ * the hypervisor due to lost credit (core removal on pseries).
+ * So if the window is not active, return mmap() failure with
+ * -EACCES and expects the user space reissue mmap() when it
+ * is active again or open new window when the credit is available.
+ * mmap_mutex protects the paste address mmap() with DLPAR
+ * close/open event and allows mmap() only when the window is
+ * active.
+ */
+ mutex_lock(&txwin->task_ref.mmap_mutex);
+ if (txwin->status != VAS_WIN_ACTIVE) {
+ pr_err("Window is not active\n");
+ rc = -EACCES;
+ goto out;
+ }
+
+ paste_addr = cp_inst->coproc->vops->paste_addr(txwin);
+ if (!paste_addr) {
+ pr_err("Window paste address failed\n");
+ rc = -EINVAL;
+ goto out;
+ }
+
+ pfn = paste_addr >> PAGE_SHIFT;
+
+ /* 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);
+
+ prot = __pgprot(pgprot_val(vma->vm_page_prot) | _PAGE_DIRTY);
+
+ rc = remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
+ vma->vm_end - vma->vm_start, prot);
+
+ pr_devel("paste addr %llx at %lx, rc %d\n", paste_addr,
+ vma->vm_start, rc);
+
+ txwin->task_ref.vma = vma;
+ vma->vm_ops = &vas_vm_ops;
+
+out:
+ mutex_unlock(&txwin->task_ref.mmap_mutex);
+ return rc;
+}
+
+static long coproc_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
+{
+ switch (cmd) {
+ case VAS_TX_WIN_OPEN:
+ return coproc_ioc_tx_win_open(fp, arg);
+ default:
+ return -EINVAL;
+ }
+}
+
+static struct file_operations coproc_fops = {
+ .open = coproc_open,
+ .release = coproc_release,
+ .mmap = coproc_mmap,
+ .unlocked_ioctl = coproc_ioctl,
+};
+
+/*
+ * Supporting only nx-gzip coprocessor type now, but this API code
+ * extended to other coprocessor types later.
+ */
+int vas_register_coproc_api(struct module *mod, enum vas_cop_type cop_type,
+ const char *name,
+ const struct vas_user_win_ops *vops)
+{
+ int rc = -EINVAL;
+ dev_t devno;
+
+ rc = alloc_chrdev_region(&coproc_device.devt, 1, 1, name);
+ if (rc) {
+ pr_err("Unable to allocate coproc major number: %i\n", rc);
+ return rc;
+ }
+
+ pr_devel("%s device allocated, dev [%i,%i]\n", name,
+ MAJOR(coproc_device.devt), MINOR(coproc_device.devt));
+
+ coproc_device.class = class_create(mod, name);
+ if (IS_ERR(coproc_device.class)) {
+ rc = PTR_ERR(coproc_device.class);
+ pr_err("Unable to create %s class %d\n", name, rc);
+ goto err_class;
+ }
+ coproc_device.class->devnode = coproc_devnode;
+ coproc_device.cop_type = cop_type;
+ coproc_device.vops = vops;
+
+ coproc_fops.owner = mod;
+ cdev_init(&coproc_device.cdev, &coproc_fops);
+
+ devno = MKDEV(MAJOR(coproc_device.devt), 0);
+ rc = cdev_add(&coproc_device.cdev, devno, 1);
+ if (rc) {
+ pr_err("cdev_add() failed %d\n", rc);
+ goto err_cdev;
+ }
+
+ coproc_device.device = device_create(coproc_device.class, NULL,
+ devno, NULL, name, MINOR(devno));
+ if (IS_ERR(coproc_device.device)) {
+ rc = PTR_ERR(coproc_device.device);
+ pr_err("Unable to create coproc-%d %d\n", MINOR(devno), rc);
+ goto err;
+ }
+
+ pr_devel("Added dev [%d,%d]\n", MAJOR(devno), MINOR(devno));
+
+ return 0;
+
+err:
+ cdev_del(&coproc_device.cdev);
+err_cdev:
+ class_destroy(coproc_device.class);
+err_class:
+ unregister_chrdev_region(coproc_device.devt, 1);
+ return rc;
+}
+
+void vas_unregister_coproc_api(void)
+{
+ dev_t devno;
+
+ cdev_del(&coproc_device.cdev);
+ devno = MKDEV(MAJOR(coproc_device.devt), 0);
+ device_destroy(coproc_device.class, devno);
+
+ class_destroy(coproc_device.class);
+ unregister_chrdev_region(coproc_device.devt, 1);
+}