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TOMOYO Linux Cross Reference
Linux/arch/powerpc/platforms/powernv/vas-window.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * Copyright 2016-17 IBM Corp.
  4  */
  5 
  6 #define pr_fmt(fmt) "vas: " fmt
  7 
  8 #include <linux/types.h>
  9 #include <linux/mutex.h>
 10 #include <linux/slab.h>
 11 #include <linux/io.h>
 12 #include <linux/log2.h>
 13 #include <linux/rcupdate.h>
 14 #include <linux/cred.h>
 15 #include <asm/switch_to.h>
 16 #include <asm/ppc-opcode.h>
 17 #include "vas.h"
 18 #include "copy-paste.h"
 19 
 20 #define CREATE_TRACE_POINTS
 21 #include "vas-trace.h"
 22 
 23 /*
 24  * Compute the paste address region for the window @window using the
 25  * ->paste_base_addr and ->paste_win_id_shift we got from device tree.
 26  */
 27 static void compute_paste_address(struct vas_window *window, u64 *addr, int *len)
 28 {
 29         int winid;
 30         u64 base, shift;
 31 
 32         base = window->vinst->paste_base_addr;
 33         shift = window->vinst->paste_win_id_shift;
 34         winid = window->winid;
 35 
 36         *addr  = base + (winid << shift);
 37         if (len)
 38                 *len = PAGE_SIZE;
 39 
 40         pr_debug("Txwin #%d: Paste addr 0x%llx\n", winid, *addr);
 41 }
 42 
 43 static inline void get_hvwc_mmio_bar(struct vas_window *window,
 44                         u64 *start, int *len)
 45 {
 46         u64 pbaddr;
 47 
 48         pbaddr = window->vinst->hvwc_bar_start;
 49         *start = pbaddr + window->winid * VAS_HVWC_SIZE;
 50         *len = VAS_HVWC_SIZE;
 51 }
 52 
 53 static inline void get_uwc_mmio_bar(struct vas_window *window,
 54                         u64 *start, int *len)
 55 {
 56         u64 pbaddr;
 57 
 58         pbaddr = window->vinst->uwc_bar_start;
 59         *start = pbaddr + window->winid * VAS_UWC_SIZE;
 60         *len = VAS_UWC_SIZE;
 61 }
 62 
 63 /*
 64  * Map the paste bus address of the given send window into kernel address
 65  * space. Unlike MMIO regions (map_mmio_region() below), paste region must
 66  * be mapped cache-able and is only applicable to send windows.
 67  */
 68 static void *map_paste_region(struct vas_window *txwin)
 69 {
 70         int len;
 71         void *map;
 72         char *name;
 73         u64 start;
 74 
 75         name = kasprintf(GFP_KERNEL, "window-v%d-w%d", txwin->vinst->vas_id,
 76                                 txwin->winid);
 77         if (!name)
 78                 goto free_name;
 79 
 80         txwin->paste_addr_name = name;
 81         compute_paste_address(txwin, &start, &len);
 82 
 83         if (!request_mem_region(start, len, name)) {
 84                 pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
 85                                 __func__, start, len);
 86                 goto free_name;
 87         }
 88 
 89         map = ioremap_cache(start, len);
 90         if (!map) {
 91                 pr_devel("%s(): ioremap_cache(0x%llx, %d) failed\n", __func__,
 92                                 start, len);
 93                 goto free_name;
 94         }
 95 
 96         pr_devel("Mapped paste addr 0x%llx to kaddr 0x%p\n", start, map);
 97         return map;
 98 
 99 free_name:
100         kfree(name);
101         return ERR_PTR(-ENOMEM);
102 }
103 
104 static void *map_mmio_region(char *name, u64 start, int len)
105 {
106         void *map;
107 
108         if (!request_mem_region(start, len, name)) {
109                 pr_devel("%s(): request_mem_region(0x%llx, %d) failed\n",
110                                 __func__, start, len);
111                 return NULL;
112         }
113 
114         map = ioremap(start, len);
115         if (!map) {
116                 pr_devel("%s(): ioremap(0x%llx, %d) failed\n", __func__, start,
117                                 len);
118                 return NULL;
119         }
120 
121         return map;
122 }
123 
124 static void unmap_region(void *addr, u64 start, int len)
125 {
126         iounmap(addr);
127         release_mem_region((phys_addr_t)start, len);
128 }
129 
130 /*
131  * Unmap the paste address region for a window.
132  */
133 static void unmap_paste_region(struct vas_window *window)
134 {
135         int len;
136         u64 busaddr_start;
137 
138         if (window->paste_kaddr) {
139                 compute_paste_address(window, &busaddr_start, &len);
140                 unmap_region(window->paste_kaddr, busaddr_start, len);
141                 window->paste_kaddr = NULL;
142                 kfree(window->paste_addr_name);
143                 window->paste_addr_name = NULL;
144         }
145 }
146 
147 /*
148  * Unmap the MMIO regions for a window. Hold the vas_mutex so we don't
149  * unmap when the window's debugfs dir is in use. This serializes close
150  * of a window even on another VAS instance but since its not a critical
151  * path, just minimize the time we hold the mutex for now. We can add
152  * a per-instance mutex later if necessary.
153  */
154 static void unmap_winctx_mmio_bars(struct vas_window *window)
155 {
156         int len;
157         void *uwc_map;
158         void *hvwc_map;
159         u64 busaddr_start;
160 
161         mutex_lock(&vas_mutex);
162 
163         hvwc_map = window->hvwc_map;
164         window->hvwc_map = NULL;
165 
166         uwc_map = window->uwc_map;
167         window->uwc_map = NULL;
168 
169         mutex_unlock(&vas_mutex);
170 
171         if (hvwc_map) {
172                 get_hvwc_mmio_bar(window, &busaddr_start, &len);
173                 unmap_region(hvwc_map, busaddr_start, len);
174         }
175 
176         if (uwc_map) {
177                 get_uwc_mmio_bar(window, &busaddr_start, &len);
178                 unmap_region(uwc_map, busaddr_start, len);
179         }
180 }
181 
182 /*
183  * Find the Hypervisor Window Context (HVWC) MMIO Base Address Region and the
184  * OS/User Window Context (UWC) MMIO Base Address Region for the given window.
185  * Map these bus addresses and save the mapped kernel addresses in @window.
186  */
187 int map_winctx_mmio_bars(struct vas_window *window)
188 {
189         int len;
190         u64 start;
191 
192         get_hvwc_mmio_bar(window, &start, &len);
193         window->hvwc_map = map_mmio_region("HVWCM_Window", start, len);
194 
195         get_uwc_mmio_bar(window, &start, &len);
196         window->uwc_map = map_mmio_region("UWCM_Window", start, len);
197 
198         if (!window->hvwc_map || !window->uwc_map) {
199                 unmap_winctx_mmio_bars(window);
200                 return -1;
201         }
202 
203         return 0;
204 }
205 
206 /*
207  * Reset all valid registers in the HV and OS/User Window Contexts for
208  * the window identified by @window.
209  *
210  * NOTE: We cannot really use a for loop to reset window context. Not all
211  *       offsets in a window context are valid registers and the valid
212  *       registers are not sequential. And, we can only write to offsets
213  *       with valid registers.
214  */
215 void reset_window_regs(struct vas_window *window)
216 {
217         write_hvwc_reg(window, VREG(LPID), 0ULL);
218         write_hvwc_reg(window, VREG(PID), 0ULL);
219         write_hvwc_reg(window, VREG(XLATE_MSR), 0ULL);
220         write_hvwc_reg(window, VREG(XLATE_LPCR), 0ULL);
221         write_hvwc_reg(window, VREG(XLATE_CTL), 0ULL);
222         write_hvwc_reg(window, VREG(AMR), 0ULL);
223         write_hvwc_reg(window, VREG(SEIDR), 0ULL);
224         write_hvwc_reg(window, VREG(FAULT_TX_WIN), 0ULL);
225         write_hvwc_reg(window, VREG(OSU_INTR_SRC_RA), 0ULL);
226         write_hvwc_reg(window, VREG(HV_INTR_SRC_RA), 0ULL);
227         write_hvwc_reg(window, VREG(PSWID), 0ULL);
228         write_hvwc_reg(window, VREG(LFIFO_BAR), 0ULL);
229         write_hvwc_reg(window, VREG(LDATA_STAMP_CTL), 0ULL);
230         write_hvwc_reg(window, VREG(LDMA_CACHE_CTL), 0ULL);
231         write_hvwc_reg(window, VREG(LRFIFO_PUSH), 0ULL);
232         write_hvwc_reg(window, VREG(CURR_MSG_COUNT), 0ULL);
233         write_hvwc_reg(window, VREG(LNOTIFY_AFTER_COUNT), 0ULL);
234         write_hvwc_reg(window, VREG(LRX_WCRED), 0ULL);
235         write_hvwc_reg(window, VREG(LRX_WCRED_ADDER), 0ULL);
236         write_hvwc_reg(window, VREG(TX_WCRED), 0ULL);
237         write_hvwc_reg(window, VREG(TX_WCRED_ADDER), 0ULL);
238         write_hvwc_reg(window, VREG(LFIFO_SIZE), 0ULL);
239         write_hvwc_reg(window, VREG(WINCTL), 0ULL);
240         write_hvwc_reg(window, VREG(WIN_STATUS), 0ULL);
241         write_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL), 0ULL);
242         write_hvwc_reg(window, VREG(TX_RSVD_BUF_COUNT), 0ULL);
243         write_hvwc_reg(window, VREG(LRFIFO_WIN_PTR), 0ULL);
244         write_hvwc_reg(window, VREG(LNOTIFY_CTL), 0ULL);
245         write_hvwc_reg(window, VREG(LNOTIFY_PID), 0ULL);
246         write_hvwc_reg(window, VREG(LNOTIFY_LPID), 0ULL);
247         write_hvwc_reg(window, VREG(LNOTIFY_TID), 0ULL);
248         write_hvwc_reg(window, VREG(LNOTIFY_SCOPE), 0ULL);
249         write_hvwc_reg(window, VREG(NX_UTIL_ADDER), 0ULL);
250 
251         /* Skip read-only registers: NX_UTIL and NX_UTIL_SE */
252 
253         /*
254          * The send and receive window credit adder registers are also
255          * accessible from HVWC and have been initialized above. We don't
256          * need to initialize from the OS/User Window Context, so skip
257          * following calls:
258          *
259          *      write_uwc_reg(window, VREG(TX_WCRED_ADDER), 0ULL);
260          *      write_uwc_reg(window, VREG(LRX_WCRED_ADDER), 0ULL);
261          */
262 }
263 
264 /*
265  * Initialize window context registers related to Address Translation.
266  * These registers are common to send/receive windows although they
267  * differ for user/kernel windows. As we resolve the TODOs we may
268  * want to add fields to vas_winctx and move the initialization to
269  * init_vas_winctx_regs().
270  */
271 static void init_xlate_regs(struct vas_window *window, bool user_win)
272 {
273         u64 lpcr, val;
274 
275         /*
276          * MSR_TA, MSR_US are false for both kernel and user.
277          * MSR_DR and MSR_PR are false for kernel.
278          */
279         val = 0ULL;
280         val = SET_FIELD(VAS_XLATE_MSR_HV, val, 1);
281         val = SET_FIELD(VAS_XLATE_MSR_SF, val, 1);
282         if (user_win) {
283                 val = SET_FIELD(VAS_XLATE_MSR_DR, val, 1);
284                 val = SET_FIELD(VAS_XLATE_MSR_PR, val, 1);
285         }
286         write_hvwc_reg(window, VREG(XLATE_MSR), val);
287 
288         lpcr = mfspr(SPRN_LPCR);
289         val = 0ULL;
290         /*
291          * NOTE: From Section 5.7.8.1 Segment Lookaside Buffer of the
292          *       Power ISA, v3.0B, Page size encoding is 0 = 4KB, 5 = 64KB.
293          *
294          * NOTE: From Section 1.3.1, Address Translation Context of the
295          *       Nest MMU Workbook, LPCR_SC should be 0 for Power9.
296          */
297         val = SET_FIELD(VAS_XLATE_LPCR_PAGE_SIZE, val, 5);
298         val = SET_FIELD(VAS_XLATE_LPCR_ISL, val, lpcr & LPCR_ISL);
299         val = SET_FIELD(VAS_XLATE_LPCR_TC, val, lpcr & LPCR_TC);
300         val = SET_FIELD(VAS_XLATE_LPCR_SC, val, 0);
301         write_hvwc_reg(window, VREG(XLATE_LPCR), val);
302 
303         /*
304          * Section 1.3.1 (Address translation Context) of NMMU workbook.
305          *      0b00    Hashed Page Table mode
306          *      0b01    Reserved
307          *      0b10    Radix on HPT
308          *      0b11    Radix on Radix
309          */
310         val = 0ULL;
311         val = SET_FIELD(VAS_XLATE_MODE, val, radix_enabled() ? 3 : 2);
312         write_hvwc_reg(window, VREG(XLATE_CTL), val);
313 
314         /*
315          * TODO: Can we mfspr(AMR) even for user windows?
316          */
317         val = 0ULL;
318         val = SET_FIELD(VAS_AMR, val, mfspr(SPRN_AMR));
319         write_hvwc_reg(window, VREG(AMR), val);
320 
321         val = 0ULL;
322         val = SET_FIELD(VAS_SEIDR, val, 0);
323         write_hvwc_reg(window, VREG(SEIDR), val);
324 }
325 
326 /*
327  * Initialize Reserved Send Buffer Count for the send window. It involves
328  * writing to the register, reading it back to confirm that the hardware
329  * has enough buffers to reserve. See section 1.3.1.2.1 of VAS workbook.
330  *
331  * Since we can only make a best-effort attempt to fulfill the request,
332  * we don't return any errors if we cannot.
333  *
334  * TODO: Reserved (aka dedicated) send buffers are not supported yet.
335  */
336 static void init_rsvd_tx_buf_count(struct vas_window *txwin,
337                                 struct vas_winctx *winctx)
338 {
339         write_hvwc_reg(txwin, VREG(TX_RSVD_BUF_COUNT), 0ULL);
340 }
341 
342 /*
343  * init_winctx_regs()
344  *      Initialize window context registers for a receive window.
345  *      Except for caching control and marking window open, the registers
346  *      are initialized in the order listed in Section 3.1.4 (Window Context
347  *      Cache Register Details) of the VAS workbook although they don't need
348  *      to be.
349  *
350  * Design note: For NX receive windows, NX allocates the FIFO buffer in OPAL
351  *      (so that it can get a large contiguous area) and passes that buffer
352  *      to kernel via device tree. We now write that buffer address to the
353  *      FIFO BAR. Would it make sense to do this all in OPAL? i.e have OPAL
354  *      write the per-chip RX FIFO addresses to the windows during boot-up
355  *      as a one-time task? That could work for NX but what about other
356  *      receivers?  Let the receivers tell us the rx-fifo buffers for now.
357  */
358 int init_winctx_regs(struct vas_window *window, struct vas_winctx *winctx)
359 {
360         u64 val;
361         int fifo_size;
362 
363         reset_window_regs(window);
364 
365         val = 0ULL;
366         val = SET_FIELD(VAS_LPID, val, winctx->lpid);
367         write_hvwc_reg(window, VREG(LPID), val);
368 
369         val = 0ULL;
370         val = SET_FIELD(VAS_PID_ID, val, winctx->pidr);
371         write_hvwc_reg(window, VREG(PID), val);
372 
373         init_xlate_regs(window, winctx->user_win);
374 
375         val = 0ULL;
376         val = SET_FIELD(VAS_FAULT_TX_WIN, val, 0);
377         write_hvwc_reg(window, VREG(FAULT_TX_WIN), val);
378 
379         /* In PowerNV, interrupts go to HV. */
380         write_hvwc_reg(window, VREG(OSU_INTR_SRC_RA), 0ULL);
381 
382         val = 0ULL;
383         val = SET_FIELD(VAS_HV_INTR_SRC_RA, val, winctx->irq_port);
384         write_hvwc_reg(window, VREG(HV_INTR_SRC_RA), val);
385 
386         val = 0ULL;
387         val = SET_FIELD(VAS_PSWID_EA_HANDLE, val, winctx->pswid);
388         write_hvwc_reg(window, VREG(PSWID), val);
389 
390         write_hvwc_reg(window, VREG(SPARE1), 0ULL);
391         write_hvwc_reg(window, VREG(SPARE2), 0ULL);
392         write_hvwc_reg(window, VREG(SPARE3), 0ULL);
393 
394         /*
395          * NOTE: VAS expects the FIFO address to be copied into the LFIFO_BAR
396          *       register as is - do NOT shift the address into VAS_LFIFO_BAR
397          *       bit fields! Ok to set the page migration select fields -
398          *       VAS ignores the lower 10+ bits in the address anyway, because
399          *       the minimum FIFO size is 1K?
400          *
401          * See also: Design note in function header.
402          */
403         val = __pa(winctx->rx_fifo);
404         val = SET_FIELD(VAS_PAGE_MIGRATION_SELECT, val, 0);
405         write_hvwc_reg(window, VREG(LFIFO_BAR), val);
406 
407         val = 0ULL;
408         val = SET_FIELD(VAS_LDATA_STAMP, val, winctx->data_stamp);
409         write_hvwc_reg(window, VREG(LDATA_STAMP_CTL), val);
410 
411         val = 0ULL;
412         val = SET_FIELD(VAS_LDMA_TYPE, val, winctx->dma_type);
413         val = SET_FIELD(VAS_LDMA_FIFO_DISABLE, val, winctx->fifo_disable);
414         write_hvwc_reg(window, VREG(LDMA_CACHE_CTL), val);
415 
416         write_hvwc_reg(window, VREG(LRFIFO_PUSH), 0ULL);
417         write_hvwc_reg(window, VREG(CURR_MSG_COUNT), 0ULL);
418         write_hvwc_reg(window, VREG(LNOTIFY_AFTER_COUNT), 0ULL);
419 
420         val = 0ULL;
421         val = SET_FIELD(VAS_LRX_WCRED, val, winctx->wcreds_max);
422         write_hvwc_reg(window, VREG(LRX_WCRED), val);
423 
424         val = 0ULL;
425         val = SET_FIELD(VAS_TX_WCRED, val, winctx->wcreds_max);
426         write_hvwc_reg(window, VREG(TX_WCRED), val);
427 
428         write_hvwc_reg(window, VREG(LRX_WCRED_ADDER), 0ULL);
429         write_hvwc_reg(window, VREG(TX_WCRED_ADDER), 0ULL);
430 
431         fifo_size = winctx->rx_fifo_size / 1024;
432 
433         val = 0ULL;
434         val = SET_FIELD(VAS_LFIFO_SIZE, val, ilog2(fifo_size));
435         write_hvwc_reg(window, VREG(LFIFO_SIZE), val);
436 
437         /* Update window control and caching control registers last so
438          * we mark the window open only after fully initializing it and
439          * pushing context to cache.
440          */
441 
442         write_hvwc_reg(window, VREG(WIN_STATUS), 0ULL);
443 
444         init_rsvd_tx_buf_count(window, winctx);
445 
446         /* for a send window, point to the matching receive window */
447         val = 0ULL;
448         val = SET_FIELD(VAS_LRX_WIN_ID, val, winctx->rx_win_id);
449         write_hvwc_reg(window, VREG(LRFIFO_WIN_PTR), val);
450 
451         write_hvwc_reg(window, VREG(SPARE4), 0ULL);
452 
453         val = 0ULL;
454         val = SET_FIELD(VAS_NOTIFY_DISABLE, val, winctx->notify_disable);
455         val = SET_FIELD(VAS_INTR_DISABLE, val, winctx->intr_disable);
456         val = SET_FIELD(VAS_NOTIFY_EARLY, val, winctx->notify_early);
457         val = SET_FIELD(VAS_NOTIFY_OSU_INTR, val, winctx->notify_os_intr_reg);
458         write_hvwc_reg(window, VREG(LNOTIFY_CTL), val);
459 
460         val = 0ULL;
461         val = SET_FIELD(VAS_LNOTIFY_PID, val, winctx->lnotify_pid);
462         write_hvwc_reg(window, VREG(LNOTIFY_PID), val);
463 
464         val = 0ULL;
465         val = SET_FIELD(VAS_LNOTIFY_LPID, val, winctx->lnotify_lpid);
466         write_hvwc_reg(window, VREG(LNOTIFY_LPID), val);
467 
468         val = 0ULL;
469         val = SET_FIELD(VAS_LNOTIFY_TID, val, winctx->lnotify_tid);
470         write_hvwc_reg(window, VREG(LNOTIFY_TID), val);
471 
472         val = 0ULL;
473         val = SET_FIELD(VAS_LNOTIFY_MIN_SCOPE, val, winctx->min_scope);
474         val = SET_FIELD(VAS_LNOTIFY_MAX_SCOPE, val, winctx->max_scope);
475         write_hvwc_reg(window, VREG(LNOTIFY_SCOPE), val);
476 
477         /* Skip read-only registers NX_UTIL and NX_UTIL_SE */
478 
479         write_hvwc_reg(window, VREG(SPARE5), 0ULL);
480         write_hvwc_reg(window, VREG(NX_UTIL_ADDER), 0ULL);
481         write_hvwc_reg(window, VREG(SPARE6), 0ULL);
482 
483         /* Finally, push window context to memory and... */
484         val = 0ULL;
485         val = SET_FIELD(VAS_PUSH_TO_MEM, val, 1);
486         write_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL), val);
487 
488         /* ... mark the window open for business */
489         val = 0ULL;
490         val = SET_FIELD(VAS_WINCTL_REJ_NO_CREDIT, val, winctx->rej_no_credit);
491         val = SET_FIELD(VAS_WINCTL_PIN, val, winctx->pin_win);
492         val = SET_FIELD(VAS_WINCTL_TX_WCRED_MODE, val, winctx->tx_wcred_mode);
493         val = SET_FIELD(VAS_WINCTL_RX_WCRED_MODE, val, winctx->rx_wcred_mode);
494         val = SET_FIELD(VAS_WINCTL_TX_WORD_MODE, val, winctx->tx_word_mode);
495         val = SET_FIELD(VAS_WINCTL_RX_WORD_MODE, val, winctx->rx_word_mode);
496         val = SET_FIELD(VAS_WINCTL_FAULT_WIN, val, winctx->fault_win);
497         val = SET_FIELD(VAS_WINCTL_NX_WIN, val, winctx->nx_win);
498         val = SET_FIELD(VAS_WINCTL_OPEN, val, 1);
499         write_hvwc_reg(window, VREG(WINCTL), val);
500 
501         return 0;
502 }
503 
504 static void vas_release_window_id(struct ida *ida, int winid)
505 {
506         ida_free(ida, winid);
507 }
508 
509 static int vas_assign_window_id(struct ida *ida)
510 {
511         int winid = ida_alloc_max(ida, VAS_WINDOWS_PER_CHIP - 1, GFP_KERNEL);
512 
513         if (winid == -ENOSPC) {
514                 pr_err("Too many (%d) open windows\n", VAS_WINDOWS_PER_CHIP);
515                 return -EAGAIN;
516         }
517 
518         return winid;
519 }
520 
521 static void vas_window_free(struct vas_window *window)
522 {
523         int winid = window->winid;
524         struct vas_instance *vinst = window->vinst;
525 
526         unmap_winctx_mmio_bars(window);
527 
528         vas_window_free_dbgdir(window);
529 
530         kfree(window);
531 
532         vas_release_window_id(&vinst->ida, winid);
533 }
534 
535 static struct vas_window *vas_window_alloc(struct vas_instance *vinst)
536 {
537         int winid;
538         struct vas_window *window;
539 
540         winid = vas_assign_window_id(&vinst->ida);
541         if (winid < 0)
542                 return ERR_PTR(winid);
543 
544         window = kzalloc(sizeof(*window), GFP_KERNEL);
545         if (!window)
546                 goto out_free;
547 
548         window->vinst = vinst;
549         window->winid = winid;
550 
551         if (map_winctx_mmio_bars(window))
552                 goto out_free;
553 
554         vas_window_init_dbgdir(window);
555 
556         return window;
557 
558 out_free:
559         kfree(window);
560         vas_release_window_id(&vinst->ida, winid);
561         return ERR_PTR(-ENOMEM);
562 }
563 
564 static void put_rx_win(struct vas_window *rxwin)
565 {
566         /* Better not be a send window! */
567         WARN_ON_ONCE(rxwin->tx_win);
568 
569         atomic_dec(&rxwin->num_txwins);
570 }
571 
572 /*
573  * Find the user space receive window given the @pswid.
574  *      - We must have a valid vasid and it must belong to this instance.
575  *        (so both send and receive windows are on the same VAS instance)
576  *      - The window must refer to an OPEN, FTW, RECEIVE window.
577  *
578  * NOTE: We access ->windows[] table and assume that vinst->mutex is held.
579  */
580 static struct vas_window *get_user_rxwin(struct vas_instance *vinst, u32 pswid)
581 {
582         int vasid, winid;
583         struct vas_window *rxwin;
584 
585         decode_pswid(pswid, &vasid, &winid);
586 
587         if (vinst->vas_id != vasid)
588                 return ERR_PTR(-EINVAL);
589 
590         rxwin = vinst->windows[winid];
591 
592         if (!rxwin || rxwin->tx_win || rxwin->cop != VAS_COP_TYPE_FTW)
593                 return ERR_PTR(-EINVAL);
594 
595         return rxwin;
596 }
597 
598 /*
599  * Get the VAS receive window associated with NX engine identified
600  * by @cop and if applicable, @pswid.
601  *
602  * See also function header of set_vinst_win().
603  */
604 static struct vas_window *get_vinst_rxwin(struct vas_instance *vinst,
605                         enum vas_cop_type cop, u32 pswid)
606 {
607         struct vas_window *rxwin;
608 
609         mutex_lock(&vinst->mutex);
610 
611         if (cop == VAS_COP_TYPE_FTW)
612                 rxwin = get_user_rxwin(vinst, pswid);
613         else
614                 rxwin = vinst->rxwin[cop] ?: ERR_PTR(-EINVAL);
615 
616         if (!IS_ERR(rxwin))
617                 atomic_inc(&rxwin->num_txwins);
618 
619         mutex_unlock(&vinst->mutex);
620 
621         return rxwin;
622 }
623 
624 /*
625  * We have two tables of windows in a VAS instance. The first one,
626  * ->windows[], contains all the windows in the instance and allows
627  * looking up a window by its id. It is used to look up send windows
628  * during fault handling and receive windows when pairing user space
629  * send/receive windows.
630  *
631  * The second table, ->rxwin[], contains receive windows that are
632  * associated with NX engines. This table has VAS_COP_TYPE_MAX
633  * entries and is used to look up a receive window by its
634  * coprocessor type.
635  *
636  * Here, we save @window in the ->windows[] table. If it is a receive
637  * window, we also save the window in the ->rxwin[] table.
638  */
639 static void set_vinst_win(struct vas_instance *vinst,
640                         struct vas_window *window)
641 {
642         int id = window->winid;
643 
644         mutex_lock(&vinst->mutex);
645 
646         /*
647          * There should only be one receive window for a coprocessor type
648          * unless its a user (FTW) window.
649          */
650         if (!window->user_win && !window->tx_win) {
651                 WARN_ON_ONCE(vinst->rxwin[window->cop]);
652                 vinst->rxwin[window->cop] = window;
653         }
654 
655         WARN_ON_ONCE(vinst->windows[id] != NULL);
656         vinst->windows[id] = window;
657 
658         mutex_unlock(&vinst->mutex);
659 }
660 
661 /*
662  * Clear this window from the table(s) of windows for this VAS instance.
663  * See also function header of set_vinst_win().
664  */
665 static void clear_vinst_win(struct vas_window *window)
666 {
667         int id = window->winid;
668         struct vas_instance *vinst = window->vinst;
669 
670         mutex_lock(&vinst->mutex);
671 
672         if (!window->user_win && !window->tx_win) {
673                 WARN_ON_ONCE(!vinst->rxwin[window->cop]);
674                 vinst->rxwin[window->cop] = NULL;
675         }
676 
677         WARN_ON_ONCE(vinst->windows[id] != window);
678         vinst->windows[id] = NULL;
679 
680         mutex_unlock(&vinst->mutex);
681 }
682 
683 static void init_winctx_for_rxwin(struct vas_window *rxwin,
684                         struct vas_rx_win_attr *rxattr,
685                         struct vas_winctx *winctx)
686 {
687         /*
688          * We first zero (memset()) all fields and only set non-zero fields.
689          * Following fields are 0/false but maybe deserve a comment:
690          *
691          *      ->notify_os_intr_reg    In powerNV, send intrs to HV
692          *      ->notify_disable        False for NX windows
693          *      ->intr_disable          False for Fault Windows
694          *      ->xtra_write            False for NX windows
695          *      ->notify_early          NA for NX windows
696          *      ->rsvd_txbuf_count      NA for Rx windows
697          *      ->lpid, ->pid, ->tid    NA for Rx windows
698          */
699 
700         memset(winctx, 0, sizeof(struct vas_winctx));
701 
702         winctx->rx_fifo = rxattr->rx_fifo;
703         winctx->rx_fifo_size = rxattr->rx_fifo_size;
704         winctx->wcreds_max = rxwin->wcreds_max;
705         winctx->pin_win = rxattr->pin_win;
706 
707         winctx->nx_win = rxattr->nx_win;
708         winctx->fault_win = rxattr->fault_win;
709         winctx->user_win = rxattr->user_win;
710         winctx->rej_no_credit = rxattr->rej_no_credit;
711         winctx->rx_word_mode = rxattr->rx_win_ord_mode;
712         winctx->tx_word_mode = rxattr->tx_win_ord_mode;
713         winctx->rx_wcred_mode = rxattr->rx_wcred_mode;
714         winctx->tx_wcred_mode = rxattr->tx_wcred_mode;
715         winctx->notify_early = rxattr->notify_early;
716 
717         if (winctx->nx_win) {
718                 winctx->data_stamp = true;
719                 winctx->intr_disable = true;
720                 winctx->pin_win = true;
721 
722                 WARN_ON_ONCE(winctx->fault_win);
723                 WARN_ON_ONCE(!winctx->rx_word_mode);
724                 WARN_ON_ONCE(!winctx->tx_word_mode);
725                 WARN_ON_ONCE(winctx->notify_after_count);
726         } else if (winctx->fault_win) {
727                 winctx->notify_disable = true;
728         } else if (winctx->user_win) {
729                 /*
730                  * Section 1.8.1 Low Latency Core-Core Wake up of
731                  * the VAS workbook:
732                  *
733                  *      - disable credit checks ([tr]x_wcred_mode = false)
734                  *      - disable FIFO writes
735                  *      - enable ASB_Notify, disable interrupt
736                  */
737                 winctx->fifo_disable = true;
738                 winctx->intr_disable = true;
739                 winctx->rx_fifo = NULL;
740         }
741 
742         winctx->lnotify_lpid = rxattr->lnotify_lpid;
743         winctx->lnotify_pid = rxattr->lnotify_pid;
744         winctx->lnotify_tid = rxattr->lnotify_tid;
745         winctx->pswid = rxattr->pswid;
746         winctx->dma_type = VAS_DMA_TYPE_INJECT;
747         winctx->tc_mode = rxattr->tc_mode;
748 
749         winctx->min_scope = VAS_SCOPE_LOCAL;
750         winctx->max_scope = VAS_SCOPE_VECTORED_GROUP;
751 }
752 
753 static bool rx_win_args_valid(enum vas_cop_type cop,
754                         struct vas_rx_win_attr *attr)
755 {
756         pr_debug("Rxattr: fault %d, notify %d, intr %d, early %d, fifo %d\n",
757                         attr->fault_win, attr->notify_disable,
758                         attr->intr_disable, attr->notify_early,
759                         attr->rx_fifo_size);
760 
761         if (cop >= VAS_COP_TYPE_MAX)
762                 return false;
763 
764         if (cop != VAS_COP_TYPE_FTW &&
765                                 attr->rx_fifo_size < VAS_RX_FIFO_SIZE_MIN)
766                 return false;
767 
768         if (attr->rx_fifo_size > VAS_RX_FIFO_SIZE_MAX)
769                 return false;
770 
771         if (attr->wcreds_max > VAS_RX_WCREDS_MAX)
772                 return false;
773 
774         if (attr->nx_win) {
775                 /* cannot be fault or user window if it is nx */
776                 if (attr->fault_win || attr->user_win)
777                         return false;
778                 /*
779                  * Section 3.1.4.32: NX Windows must not disable notification,
780                  *      and must not enable interrupts or early notification.
781                  */
782                 if (attr->notify_disable || !attr->intr_disable ||
783                                 attr->notify_early)
784                         return false;
785         } else if (attr->fault_win) {
786                 /* cannot be both fault and user window */
787                 if (attr->user_win)
788                         return false;
789 
790                 /*
791                  * Section 3.1.4.32: Fault windows must disable notification
792                  *      but not interrupts.
793                  */
794                 if (!attr->notify_disable || attr->intr_disable)
795                         return false;
796 
797         } else if (attr->user_win) {
798                 /*
799                  * User receive windows are only for fast-thread-wakeup
800                  * (FTW). They don't need a FIFO and must disable interrupts
801                  */
802                 if (attr->rx_fifo || attr->rx_fifo_size || !attr->intr_disable)
803                         return false;
804         } else {
805                 /* Rx window must be one of NX or Fault or User window. */
806                 return false;
807         }
808 
809         return true;
810 }
811 
812 void vas_init_rx_win_attr(struct vas_rx_win_attr *rxattr, enum vas_cop_type cop)
813 {
814         memset(rxattr, 0, sizeof(*rxattr));
815 
816         if (cop == VAS_COP_TYPE_842 || cop == VAS_COP_TYPE_842_HIPRI) {
817                 rxattr->pin_win = true;
818                 rxattr->nx_win = true;
819                 rxattr->fault_win = false;
820                 rxattr->intr_disable = true;
821                 rxattr->rx_wcred_mode = true;
822                 rxattr->tx_wcred_mode = true;
823                 rxattr->rx_win_ord_mode = true;
824                 rxattr->tx_win_ord_mode = true;
825         } else if (cop == VAS_COP_TYPE_FAULT) {
826                 rxattr->pin_win = true;
827                 rxattr->fault_win = true;
828                 rxattr->notify_disable = true;
829                 rxattr->rx_wcred_mode = true;
830                 rxattr->tx_wcred_mode = true;
831                 rxattr->rx_win_ord_mode = true;
832                 rxattr->tx_win_ord_mode = true;
833         } else if (cop == VAS_COP_TYPE_FTW) {
834                 rxattr->user_win = true;
835                 rxattr->intr_disable = true;
836 
837                 /*
838                  * As noted in the VAS Workbook we disable credit checks.
839                  * If we enable credit checks in the future, we must also
840                  * implement a mechanism to return the user credits or new
841                  * paste operations will fail.
842                  */
843         }
844 }
845 EXPORT_SYMBOL_GPL(vas_init_rx_win_attr);
846 
847 struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
848                         struct vas_rx_win_attr *rxattr)
849 {
850         struct vas_window *rxwin;
851         struct vas_winctx winctx;
852         struct vas_instance *vinst;
853 
854         trace_vas_rx_win_open(current, vasid, cop, rxattr);
855 
856         if (!rx_win_args_valid(cop, rxattr))
857                 return ERR_PTR(-EINVAL);
858 
859         vinst = find_vas_instance(vasid);
860         if (!vinst) {
861                 pr_devel("vasid %d not found!\n", vasid);
862                 return ERR_PTR(-EINVAL);
863         }
864         pr_devel("Found instance %d\n", vasid);
865 
866         rxwin = vas_window_alloc(vinst);
867         if (IS_ERR(rxwin)) {
868                 pr_devel("Unable to allocate memory for Rx window\n");
869                 return rxwin;
870         }
871 
872         rxwin->tx_win = false;
873         rxwin->nx_win = rxattr->nx_win;
874         rxwin->user_win = rxattr->user_win;
875         rxwin->cop = cop;
876         rxwin->wcreds_max = rxattr->wcreds_max ?: VAS_WCREDS_DEFAULT;
877         if (rxattr->user_win)
878                 rxwin->pid = task_pid_vnr(current);
879 
880         init_winctx_for_rxwin(rxwin, rxattr, &winctx);
881         init_winctx_regs(rxwin, &winctx);
882 
883         set_vinst_win(vinst, rxwin);
884 
885         return rxwin;
886 }
887 EXPORT_SYMBOL_GPL(vas_rx_win_open);
888 
889 void vas_init_tx_win_attr(struct vas_tx_win_attr *txattr, enum vas_cop_type cop)
890 {
891         memset(txattr, 0, sizeof(*txattr));
892 
893         if (cop == VAS_COP_TYPE_842 || cop == VAS_COP_TYPE_842_HIPRI) {
894                 txattr->rej_no_credit = false;
895                 txattr->rx_wcred_mode = true;
896                 txattr->tx_wcred_mode = true;
897                 txattr->rx_win_ord_mode = true;
898                 txattr->tx_win_ord_mode = true;
899         } else if (cop == VAS_COP_TYPE_FTW) {
900                 txattr->user_win = true;
901         }
902 }
903 EXPORT_SYMBOL_GPL(vas_init_tx_win_attr);
904 
905 static void init_winctx_for_txwin(struct vas_window *txwin,
906                         struct vas_tx_win_attr *txattr,
907                         struct vas_winctx *winctx)
908 {
909         /*
910          * We first zero all fields and only set non-zero ones. Following
911          * are some fields set to 0/false for the stated reason:
912          *
913          *      ->notify_os_intr_reg    In powernv, send intrs to HV
914          *      ->rsvd_txbuf_count      Not supported yet.
915          *      ->notify_disable        False for NX windows
916          *      ->xtra_write            False for NX windows
917          *      ->notify_early          NA for NX windows
918          *      ->lnotify_lpid          NA for Tx windows
919          *      ->lnotify_pid           NA for Tx windows
920          *      ->lnotify_tid           NA for Tx windows
921          *      ->tx_win_cred_mode      Ignore for now for NX windows
922          *      ->rx_win_cred_mode      Ignore for now for NX windows
923          */
924         memset(winctx, 0, sizeof(struct vas_winctx));
925 
926         winctx->wcreds_max = txwin->wcreds_max;
927 
928         winctx->user_win = txattr->user_win;
929         winctx->nx_win = txwin->rxwin->nx_win;
930         winctx->pin_win = txattr->pin_win;
931         winctx->rej_no_credit = txattr->rej_no_credit;
932         winctx->rsvd_txbuf_enable = txattr->rsvd_txbuf_enable;
933 
934         winctx->rx_wcred_mode = txattr->rx_wcred_mode;
935         winctx->tx_wcred_mode = txattr->tx_wcred_mode;
936         winctx->rx_word_mode = txattr->rx_win_ord_mode;
937         winctx->tx_word_mode = txattr->tx_win_ord_mode;
938         winctx->rsvd_txbuf_count = txattr->rsvd_txbuf_count;
939 
940         winctx->intr_disable = true;
941         if (winctx->nx_win)
942                 winctx->data_stamp = true;
943 
944         winctx->lpid = txattr->lpid;
945         winctx->pidr = txattr->pidr;
946         winctx->rx_win_id = txwin->rxwin->winid;
947 
948         winctx->dma_type = VAS_DMA_TYPE_INJECT;
949         winctx->tc_mode = txattr->tc_mode;
950         winctx->min_scope = VAS_SCOPE_LOCAL;
951         winctx->max_scope = VAS_SCOPE_VECTORED_GROUP;
952 
953         winctx->pswid = 0;
954 }
955 
956 static bool tx_win_args_valid(enum vas_cop_type cop,
957                         struct vas_tx_win_attr *attr)
958 {
959         if (attr->tc_mode != VAS_THRESH_DISABLED)
960                 return false;
961 
962         if (cop > VAS_COP_TYPE_MAX)
963                 return false;
964 
965         if (attr->wcreds_max > VAS_TX_WCREDS_MAX)
966                 return false;
967 
968         if (attr->user_win &&
969                         (cop != VAS_COP_TYPE_FTW || attr->rsvd_txbuf_count))
970                 return false;
971 
972         return true;
973 }
974 
975 struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
976                         struct vas_tx_win_attr *attr)
977 {
978         int rc;
979         struct vas_window *txwin;
980         struct vas_window *rxwin;
981         struct vas_winctx winctx;
982         struct vas_instance *vinst;
983 
984         trace_vas_tx_win_open(current, vasid, cop, attr);
985 
986         if (!tx_win_args_valid(cop, attr))
987                 return ERR_PTR(-EINVAL);
988 
989         /*
990          * If caller did not specify a vasid but specified the PSWID of a
991          * receive window (applicable only to FTW windows), use the vasid
992          * from that receive window.
993          */
994         if (vasid == -1 && attr->pswid)
995                 decode_pswid(attr->pswid, &vasid, NULL);
996 
997         vinst = find_vas_instance(vasid);
998         if (!vinst) {
999                 pr_devel("vasid %d not found!\n", vasid);
1000                 return ERR_PTR(-EINVAL);
1001         }
1002 
1003         rxwin = get_vinst_rxwin(vinst, cop, attr->pswid);
1004         if (IS_ERR(rxwin)) {
1005                 pr_devel("No RxWin for vasid %d, cop %d\n", vasid, cop);
1006                 return rxwin;
1007         }
1008 
1009         txwin = vas_window_alloc(vinst);
1010         if (IS_ERR(txwin)) {
1011                 rc = PTR_ERR(txwin);
1012                 goto put_rxwin;
1013         }
1014 
1015         txwin->cop = cop;
1016         txwin->tx_win = 1;
1017         txwin->rxwin = rxwin;
1018         txwin->nx_win = txwin->rxwin->nx_win;
1019         txwin->pid = attr->pid;
1020         txwin->user_win = attr->user_win;
1021         txwin->wcreds_max = attr->wcreds_max ?: VAS_WCREDS_DEFAULT;
1022 
1023         init_winctx_for_txwin(txwin, attr, &winctx);
1024 
1025         init_winctx_regs(txwin, &winctx);
1026 
1027         /*
1028          * If its a kernel send window, map the window address into the
1029          * kernel's address space. For user windows, user must issue an
1030          * mmap() to map the window into their address space.
1031          *
1032          * NOTE: If kernel ever resubmits a user CRB after handling a page
1033          *       fault, we will need to map this into kernel as well.
1034          */
1035         if (!txwin->user_win) {
1036                 txwin->paste_kaddr = map_paste_region(txwin);
1037                 if (IS_ERR(txwin->paste_kaddr)) {
1038                         rc = PTR_ERR(txwin->paste_kaddr);
1039                         goto free_window;
1040                 }
1041         } else {
1042                 /*
1043                  * A user mapping must ensure that context switch issues
1044                  * CP_ABORT for this thread.
1045                  */
1046                 rc = set_thread_uses_vas();
1047                 if (rc)
1048                         goto free_window;
1049         }
1050 
1051         set_vinst_win(vinst, txwin);
1052 
1053         return txwin;
1054 
1055 free_window:
1056         vas_window_free(txwin);
1057 
1058 put_rxwin:
1059         put_rx_win(rxwin);
1060         return ERR_PTR(rc);
1061 
1062 }
1063 EXPORT_SYMBOL_GPL(vas_tx_win_open);
1064 
1065 int vas_copy_crb(void *crb, int offset)
1066 {
1067         return vas_copy(crb, offset);
1068 }
1069 EXPORT_SYMBOL_GPL(vas_copy_crb);
1070 
1071 #define RMA_LSMP_REPORT_ENABLE PPC_BIT(53)
1072 int vas_paste_crb(struct vas_window *txwin, int offset, bool re)
1073 {
1074         int rc;
1075         void *addr;
1076         uint64_t val;
1077 
1078         trace_vas_paste_crb(current, txwin);
1079 
1080         /*
1081          * Only NX windows are supported for now and hardware assumes
1082          * report-enable flag is set for NX windows. Ensure software
1083          * complies too.
1084          */
1085         WARN_ON_ONCE(txwin->nx_win && !re);
1086 
1087         addr = txwin->paste_kaddr;
1088         if (re) {
1089                 /*
1090                  * Set the REPORT_ENABLE bit (equivalent to writing
1091                  * to 1K offset of the paste address)
1092                  */
1093                 val = SET_FIELD(RMA_LSMP_REPORT_ENABLE, 0ULL, 1);
1094                 addr += val;
1095         }
1096 
1097         /*
1098          * Map the raw CR value from vas_paste() to an error code (there
1099          * is just pass or fail for now though).
1100          */
1101         rc = vas_paste(addr, offset);
1102         if (rc == 2)
1103                 rc = 0;
1104         else
1105                 rc = -EINVAL;
1106 
1107         pr_debug("Txwin #%d: Msg count %llu\n", txwin->winid,
1108                         read_hvwc_reg(txwin, VREG(LRFIFO_PUSH)));
1109 
1110         return rc;
1111 }
1112 EXPORT_SYMBOL_GPL(vas_paste_crb);
1113 
1114 /*
1115  * If credit checking is enabled for this window, poll for the return
1116  * of window credits (i.e for NX engines to process any outstanding CRBs).
1117  * Since NX-842 waits for the CRBs to be processed before closing the
1118  * window, we should not have to wait for too long.
1119  *
1120  * TODO: We retry in 10ms intervals now. We could/should probably peek at
1121  *      the VAS_LRFIFO_PUSH_OFFSET register to get an estimate of pending
1122  *      CRBs on the FIFO and compute the delay dynamically on each retry.
1123  *      But that is not really needed until we support NX-GZIP access from
1124  *      user space. (NX-842 driver waits for CSB and Fast thread-wakeup
1125  *      doesn't use credit checking).
1126  */
1127 static void poll_window_credits(struct vas_window *window)
1128 {
1129         u64 val;
1130         int creds, mode;
1131 
1132         val = read_hvwc_reg(window, VREG(WINCTL));
1133         if (window->tx_win)
1134                 mode = GET_FIELD(VAS_WINCTL_TX_WCRED_MODE, val);
1135         else
1136                 mode = GET_FIELD(VAS_WINCTL_RX_WCRED_MODE, val);
1137 
1138         if (!mode)
1139                 return;
1140 retry:
1141         if (window->tx_win) {
1142                 val = read_hvwc_reg(window, VREG(TX_WCRED));
1143                 creds = GET_FIELD(VAS_TX_WCRED, val);
1144         } else {
1145                 val = read_hvwc_reg(window, VREG(LRX_WCRED));
1146                 creds = GET_FIELD(VAS_LRX_WCRED, val);
1147         }
1148 
1149         if (creds < window->wcreds_max) {
1150                 val = 0;
1151                 set_current_state(TASK_UNINTERRUPTIBLE);
1152                 schedule_timeout(msecs_to_jiffies(10));
1153                 goto retry;
1154         }
1155 }
1156 
1157 /*
1158  * Wait for the window to go to "not-busy" state. It should only take a
1159  * short time to queue a CRB, so window should not be busy for too long.
1160  * Trying 5ms intervals.
1161  */
1162 static void poll_window_busy_state(struct vas_window *window)
1163 {
1164         int busy;
1165         u64 val;
1166 
1167 retry:
1168         val = read_hvwc_reg(window, VREG(WIN_STATUS));
1169         busy = GET_FIELD(VAS_WIN_BUSY, val);
1170         if (busy) {
1171                 val = 0;
1172                 set_current_state(TASK_UNINTERRUPTIBLE);
1173                 schedule_timeout(msecs_to_jiffies(5));
1174                 goto retry;
1175         }
1176 }
1177 
1178 /*
1179  * Have the hardware cast a window out of cache and wait for it to
1180  * be completed.
1181  *
1182  * NOTE: It can take a relatively long time to cast the window context
1183  *      out of the cache. It is not strictly necessary to cast out if:
1184  *
1185  *      - we clear the "Pin Window" bit (so hardware is free to evict)
1186  *
1187  *      - we re-initialize the window context when it is reassigned.
1188  *
1189  *      We do the former in vas_win_close() and latter in vas_win_open().
1190  *      So, ignoring the cast-out for now. We can add it as needed. If
1191  *      casting out becomes necessary we should consider offloading the
1192  *      job to a worker thread, so the window close can proceed quickly.
1193  */
1194 static void poll_window_castout(struct vas_window *window)
1195 {
1196         /* stub for now */
1197 }
1198 
1199 /*
1200  * Unpin and close a window so no new requests are accepted and the
1201  * hardware can evict this window from cache if necessary.
1202  */
1203 static void unpin_close_window(struct vas_window *window)
1204 {
1205         u64 val;
1206 
1207         val = read_hvwc_reg(window, VREG(WINCTL));
1208         val = SET_FIELD(VAS_WINCTL_PIN, val, 0);
1209         val = SET_FIELD(VAS_WINCTL_OPEN, val, 0);
1210         write_hvwc_reg(window, VREG(WINCTL), val);
1211 }
1212 
1213 /*
1214  * Close a window.
1215  *
1216  * See Section 1.12.1 of VAS workbook v1.05 for details on closing window:
1217  *      - Disable new paste operations (unmap paste address)
1218  *      - Poll for the "Window Busy" bit to be cleared
1219  *      - Clear the Open/Enable bit for the Window.
1220  *      - Poll for return of window Credits (implies FIFO empty for Rx win?)
1221  *      - Unpin and cast window context out of cache
1222  *
1223  * Besides the hardware, kernel has some bookkeeping of course.
1224  */
1225 int vas_win_close(struct vas_window *window)
1226 {
1227         if (!window)
1228                 return 0;
1229 
1230         if (!window->tx_win && atomic_read(&window->num_txwins) != 0) {
1231                 pr_devel("Attempting to close an active Rx window!\n");
1232                 WARN_ON_ONCE(1);
1233                 return -EBUSY;
1234         }
1235 
1236         unmap_paste_region(window);
1237 
1238         clear_vinst_win(window);
1239 
1240         poll_window_busy_state(window);
1241 
1242         unpin_close_window(window);
1243 
1244         poll_window_credits(window);
1245 
1246         poll_window_castout(window);
1247 
1248         /* if send window, drop reference to matching receive window */
1249         if (window->tx_win)
1250                 put_rx_win(window->rxwin);
1251 
1252         vas_window_free(window);
1253 
1254         return 0;
1255 }
1256 EXPORT_SYMBOL_GPL(vas_win_close);
1257 

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