#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/kthread.h>
+#include <linux/mmu_context.h>
#include <asm/icswx.h>
#include "vas.h"
*/
#define VAS_FAULT_WIN_FIFO_SIZE (4 << 20)
+/*
+ * Process valid CRBs in fault FIFO.
+ * NX process user space requests, return credit and update the status
+ * in CRB. If it encounters transalation error when accessing CRB or
+ * request buffers, raises interrupt on the CPU to handle the fault.
+ * It takes credit on fault window, updates nx_fault_stamp in CRB with
+ * the following information and pastes CRB in fault FIFO.
+ *
+ * pswid - window ID of the window on which the request is sent.
+ * fault_storage_addr - fault address
+ *
+ * It can raise a single interrupt for multiple faults. Expects OS to
+ * process all valid faults and return credit for each fault on user
+ * space and fault windows. This fault FIFO control will be done with
+ * credit mechanism. NX can continuously paste CRBs until credits are not
+ * available on fault window. Otherwise, returns with RMA_reject.
+ *
+ * Total credits available on fault window: FIFO_SIZE(4MB)/CRBS_SIZE(128)
+ *
+ */
+irqreturn_t vas_fault_thread_fn(int irq, void *data)
+{
+ struct vas_instance *vinst = data;
+ struct coprocessor_request_block *crb, *entry;
+ struct coprocessor_request_block buf;
+ struct vas_window *window;
+ unsigned long flags;
+ void *fifo;
+
+ crb = &buf;
+
+ /*
+ * VAS can interrupt with multiple page faults. So process all
+ * valid CRBs within fault FIFO until reaches invalid CRB.
+ * We use CCW[0] and pswid to validate validate CRBs:
+ *
+ * CCW[0] Reserved bit. When NX pastes CRB, CCW[0]=0
+ * OS sets this bit to 1 after reading CRB.
+ * pswid NX assigns window ID. Set pswid to -1 after
+ * reading CRB from fault FIFO.
+ *
+ * We exit this function if no valid CRBs are available to process.
+ * So acquire fault_lock and reset fifo_in_progress to 0 before
+ * exit.
+ * In case kernel receives another interrupt with different page
+ * fault, interrupt handler returns with IRQ_HANDLED if
+ * fifo_in_progress is set. Means these new faults will be
+ * handled by the current thread. Otherwise set fifo_in_progress
+ * and return IRQ_WAKE_THREAD to wake up thread.
+ */
+ while (true) {
+ spin_lock_irqsave(&vinst->fault_lock, flags);
+ /*
+ * Advance the fault fifo pointer to next CRB.
+ * Use CRB_SIZE rather than sizeof(*crb) since the latter is
+ * aligned to CRB_ALIGN (256) but the CRB written to by VAS is
+ * only CRB_SIZE in len.
+ */
+ fifo = vinst->fault_fifo + (vinst->fault_crbs * CRB_SIZE);
+ entry = fifo;
+
+ if ((entry->stamp.nx.pswid == cpu_to_be32(FIFO_INVALID_ENTRY))
+ || (entry->ccw & cpu_to_be32(CCW0_INVALID))) {
+ vinst->fifo_in_progress = 0;
+ spin_unlock_irqrestore(&vinst->fault_lock, flags);
+ return IRQ_HANDLED;
+ }
+
+ spin_unlock_irqrestore(&vinst->fault_lock, flags);
+ vinst->fault_crbs++;
+ if (vinst->fault_crbs == (vinst->fault_fifo_size / CRB_SIZE))
+ vinst->fault_crbs = 0;
+
+ memcpy(crb, fifo, CRB_SIZE);
+ entry->stamp.nx.pswid = cpu_to_be32(FIFO_INVALID_ENTRY);
+ entry->ccw |= cpu_to_be32(CCW0_INVALID);
+
+ pr_devel("VAS[%d] fault_fifo %p, fifo %p, fault_crbs %d\n",
+ vinst->vas_id, vinst->fault_fifo, fifo,
+ vinst->fault_crbs);
+
+ window = vas_pswid_to_window(vinst,
+ be32_to_cpu(crb->stamp.nx.pswid));
+
+ if (IS_ERR(window)) {
+ /*
+ * We got an interrupt about a specific send
+ * window but we can't find that window and we can't
+ * even clean it up (return credit on user space
+ * window).
+ * But we should not get here.
+ * TODO: Disable IRQ.
+ */
+ pr_err("VAS[%d] fault_fifo %p, fifo %p, pswid 0x%x, fault_crbs %d bad CRB?\n",
+ vinst->vas_id, vinst->fault_fifo, fifo,
+ be32_to_cpu(crb->stamp.nx.pswid),
+ vinst->fault_crbs);
+
+ WARN_ON_ONCE(1);
+ }
+
+ }
+}
+
+irqreturn_t vas_fault_handler(int irq, void *dev_id)
+{
+ struct vas_instance *vinst = dev_id;
+ irqreturn_t ret = IRQ_WAKE_THREAD;
+ unsigned long flags;
+
+ /*
+ * NX can generate an interrupt for multiple faults. So the
+ * fault handler thread process all CRBs until finds invalid
+ * entry. In case if NX sees continuous faults, it is possible
+ * that the thread function entered with the first interrupt
+ * can execute and process all valid CRBs.
+ * So wake up thread only if the fault thread is not in progress.
+ */
+ spin_lock_irqsave(&vinst->fault_lock, flags);
+
+ if (vinst->fifo_in_progress)
+ ret = IRQ_HANDLED;
+ else
+ vinst->fifo_in_progress = 1;
+
+ spin_unlock_irqrestore(&vinst->fault_lock, flags);
+
+ return ret;
+}
+
/*
* Fault window is opened per VAS instance. NX pastes fault CRB in fault
* FIFO upon page faults.
goto free_window;
}
} else {
+ /*
+ * Interrupt hanlder or fault window setup failed. Means
+ * NX can not generate fault for page fault. So not
+ * opening for user space tx window.
+ */
+ if (!vinst->virq) {
+ rc = -ENODEV;
+ goto free_window;
+ }
/*
* A user mapping must ensure that context switch issues
* CP_ABORT for this thread.
return 0;
}
EXPORT_SYMBOL_GPL(vas_win_close);
+
+struct vas_window *vas_pswid_to_window(struct vas_instance *vinst,
+ uint32_t pswid)
+{
+ struct vas_window *window;
+ int winid;
+
+ if (!pswid) {
+ pr_devel("%s: called for pswid 0!\n", __func__);
+ return ERR_PTR(-ESRCH);
+ }
+
+ decode_pswid(pswid, NULL, &winid);
+
+ if (winid >= VAS_WINDOWS_PER_CHIP)
+ return ERR_PTR(-ESRCH);
+
+ /*
+ * If application closes the window before the hardware
+ * returns the fault CRB, we should wait in vas_win_close()
+ * for the pending requests. so the window must be active
+ * and the process alive.
+ *
+ * If its a kernel process, we should not get any faults and
+ * should not get here.
+ */
+ window = vinst->windows[winid];
+
+ if (!window) {
+ pr_err("PSWID decode: Could not find window for winid %d pswid %d vinst 0x%p\n",
+ winid, pswid, vinst);
+ return NULL;
+ }
+
+ /*
+ * Do some sanity checks on the decoded window. Window should be
+ * NX GZIP user send window. FTW windows should not incur faults
+ * since their CRBs are ignored (not queued on FIFO or processed
+ * by NX).
+ */
+ if (!window->tx_win || !window->user_win || !window->nx_win ||
+ window->cop == VAS_COP_TYPE_FAULT ||
+ window->cop == VAS_COP_TYPE_FTW) {
+ pr_err("PSWID decode: id %d, tx %d, user %d, nx %d, cop %d\n",
+ winid, window->tx_win, window->user_win,
+ window->nx_win, window->cop);
+ WARN_ON(1);
+ }
+
+ return window;
+}
#include <linux/of_platform.h>
#include <linux/of_address.h>
#include <linux/of.h>
+#include <linux/irqdomain.h>
+#include <linux/interrupt.h>
#include <asm/prom.h>
#include <asm/xive.h>
static int vas_irq_fault_window_setup(struct vas_instance *vinst)
{
- return vas_setup_fault_window(vinst);
+ char devname[64];
+ int rc = 0;
+
+ snprintf(devname, sizeof(devname), "vas-%d", vinst->vas_id);
+ rc = request_threaded_irq(vinst->virq, vas_fault_handler,
+ vas_fault_thread_fn, 0, devname, vinst);
+
+ if (rc) {
+ pr_err("VAS[%d]: Request IRQ(%d) failed with %d\n",
+ vinst->vas_id, vinst->virq, rc);
+ goto out;
+ }
+
+ rc = vas_setup_fault_window(vinst);
+ if (rc)
+ free_irq(vinst->virq, vinst);
+
+out:
+ return rc;
}
static int init_vas_instance(struct platform_device *pdev)
list_add(&vinst->node, &vas_instances);
mutex_unlock(&vas_mutex);
+ spin_lock_init(&vinst->fault_lock);
/*
* IRQ and fault handling setup is needed only for user space
* send windows.
projects / linux.git / commitdiff