diff options
Diffstat (limited to 'arch/powerpc/platforms/book3s/vas-api.c')
-rw-r--r-- | arch/powerpc/platforms/book3s/vas-api.c | 634 |
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 0000000000..f381b177ea --- /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(const 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_vma_pages 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 */ + vm_flags_set(vma, 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(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); +} |