Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
PCI: Stop over-estimating bridge window size
New way to calculate the bridge window head alignment produces tight-fit,
that is, it does not leave any gaps between the resources. Similarly,
relaxed tail alignment does not leave extra tail room.
Start to use bridge window calculation that does not over-estimate the size
of the required window.
pbus_upstream_space_available() can be removed.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Malte Schröder <malte+lkml@tnxip.de>
Link: https://patch.msgid.link/20251219174036.16738-4-ilpo.jarvinen@linux.intel.com
authored by
Ilpo Järvinen
and committed by
Bjorn Helgaas
3958bf16
bc75c8e5
+5
-92
+5
-92
drivers/pci/setup-bus.c
+5
-92
drivers/pci/setup-bus.c
···
1268
1268
}
1269
1269
1270
1270
/**
1271
-
* pbus_upstream_space_available - Check no upstream resource limits allocation
1272
-
* @bus: The bus
1273
-
* @res: The resource to help select the correct bridge window
1274
-
* @size: The size required from the bridge window
1275
-
* @align: Required alignment for the resource
1276
-
*
1277
-
* Check that @size can fit inside the upstream bridge resources that are
1278
-
* already assigned. Select the upstream bridge window based on the type of
1279
-
* @res.
1280
-
*
1281
-
* Return: %true if enough space is available on all assigned upstream
1282
-
* resources.
1283
-
*/
1284
-
static bool pbus_upstream_space_available(struct pci_bus *bus,
1285
-
struct resource *res,
1286
-
resource_size_t size,
1287
-
resource_size_t align)
1288
-
{
1289
-
struct resource_constraint constraint = {
1290
-
.max = RESOURCE_SIZE_MAX,
1291
-
.align = align,
1292
-
};
1293
-
struct pci_bus *downstream = bus;
1294
-
1295
-
while ((bus = bus->parent)) {
1296
-
if (pci_is_root_bus(bus))
1297
-
break;
1298
-
1299
-
res = pbus_select_window(bus, res);
1300
-
if (!res)
1301
-
return false;
1302
-
if (!res->parent)
1303
-
continue;
1304
-
1305
-
if (resource_size(res) >= size) {
1306
-
struct resource gap = {};
1307
-
1308
-
if (find_resource_space(res, &gap, size, &constraint) == 0) {
1309
-
gap.flags = res->flags;
1310
-
pci_dbg(bus->self,
1311
-
"Assigned bridge window %pR to %pR free space at %pR\n",
1312
-
res, &bus->busn_res, &gap);
1313
-
return true;
1314
-
}
1315
-
}
1316
-
1317
-
if (bus->self) {
1318
-
pci_info(bus->self,
1319
-
"Assigned bridge window %pR to %pR cannot fit 0x%llx required for %s bridging to %pR\n",
1320
-
res, &bus->busn_res,
1321
-
(unsigned long long)size,
1322
-
pci_name(downstream->self),
1323
-
&downstream->busn_res);
1324
-
}
1325
-
1326
-
return false;
1327
-
}
1328
-
1329
-
return true;
1330
-
}
1331
-
1332
-
/**
1333
1271
* pbus_size_mem() - Size the memory window of a given bus
1334
1272
*
1335
1273
* @bus: The bus
···
1293
1355
struct pci_dev *dev;
1294
1356
resource_size_t min_align, win_align, align, size, size0, size1 = 0;
1295
1357
resource_size_t aligns[28] = {}; /* Alignments from 1MB to 128TB */
1296
-
resource_size_t aligns2[28] = {};/* Alignments from 1MB to 128TB */
1297
1358
int order, max_order;
1298
1359
struct resource *b_res = pbus_select_window_for_type(bus, type);
1299
1360
resource_size_t children_add_size = 0;
···
1351
1414
continue;
1352
1415
}
1353
1416
size += max(r_size, align);
1354
-
/*
1355
-
* Exclude ranges with size > align from calculation of
1356
-
* the alignment.
1357
-
*/
1358
-
if (r_size <= align)
1359
-
aligns[order] += align;
1360
-
aligns2[order] += align;
1417
+
1418
+
aligns[order] += align;
1361
1419
if (order > max_order)
1362
1420
max_order = order;
1363
1421
···
1366
1434
1367
1435
old_size = resource_size(b_res);
1368
1436
win_align = window_alignment(bus, b_res->flags);
1369
-
min_align = calculate_mem_align(aligns, max_order);
1437
+
min_align = calculate_head_align(aligns, max_order);
1370
1438
min_align = max(min_align, win_align);
1371
-
size0 = calculate_memsize(size, min_size, 0, 0, old_size, min_align);
1439
+
size0 = calculate_memsize(size, min_size, 0, 0, old_size, win_align);
1372
1440
1373
1441
if (size0) {
1374
1442
resource_set_range(b_res, min_align, size0);
1375
1443
b_res->flags &= ~IORESOURCE_DISABLED;
1376
1444
}
1377
1445
1378
-
if (bus->self && size0 &&
1379
-
!pbus_upstream_space_available(bus, b_res, size0, min_align)) {
1380
-
min_align = calculate_head_align(aligns2, max_order);
1381
-
size0 = calculate_memsize(size, min_size, 0, 0, old_size, win_align);
1382
-
resource_set_range(b_res, min_align, size0);
1383
-
pci_info(bus->self, "bridge window %pR to %pR requires relaxed alignment rules\n",
1384
-
b_res, &bus->busn_res);
1385
-
}
1386
-
1387
1446
if (realloc_head && (add_size > 0 || children_add_size > 0)) {
1388
1447
add_align = max(min_align, add_align);
1389
1448
size1 = calculate_memsize(size, min_size, add_size, children_add_size,
1390
-
old_size, add_align);
1391
-
1392
-
if (bus->self && size1 &&
1393
-
!pbus_upstream_space_available(bus, b_res, size1, add_align)) {
1394
-
min_align = calculate_head_align(aligns2, max_order);
1395
-
size1 = calculate_memsize(size, min_size, add_size, children_add_size,
1396
-
old_size, win_align);
1397
-
pci_info(bus->self,
1398
-
"bridge window %pR to %pR requires relaxed alignment rules\n",
1399
-
b_res, &bus->busn_res);
1400
-
}
1449
+
old_size, win_align);
1401
1450
}
1402
1451
1403
1452
if (!size0 && !size1) {