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