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From: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
To: <linux-pci@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org>
Cc: Bjorn Helgaas <helgaas@kernel.org>, <linux@yadro.com>,
	Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
Subject: [PATCH v5 12/23] PCI: hotplug: movable BARs: Compute limits for relocated bridge windows
Date: Fri, 16 Aug 2019 19:50:50 +0300
Message-ID: <20190816165101.911-13-s.miroshnichenko@yadro.com> (raw)
In-Reply-To: <20190816165101.911-1-s.miroshnichenko@yadro.com>

With enabled movable BARs, bridge windows are recalculated during each pci
rescan. Some of the BARs below the bridge may be fixed/immovable: these
areas are represented by the .immovable_range field in struct pci_bus.

If a bridge window size is equal to its immovable range, it can only be
assigned to the start of this range. But if a bridge window size is larger,
and this difference in size is denoted as "delta", the window can start
from (immovable_range.start - delta) to (immovable_range.start), and it can
end from (immovable_range.end) to (immovable_range.end + delta). This range
(the new .realloc_range field in struct pci_bus) must then be compared with
immovable ranges of neighbouring bridges to guarantee no intersections.

This patch only calculates valid ranges for reallocated bridges during pci
rescan, and the next one will make use of these values during allocation.

Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
---
 drivers/pci/setup-bus.c | 67 +++++++++++++++++++++++++++++++++++++++++
 include/linux/pci.h     |  6 ++++
 2 files changed, 73 insertions(+)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 420510a1a257..586aaa9578b2 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -1819,6 +1819,72 @@ static enum enable_type pci_realloc_detect(struct pci_bus *bus,
 }
 #endif
 
+/*
+ * Calculate the address margins where the bridge windows may be allocated to fit all
+ * the fixed and immovable BARs beneath.
+ */
+static void pci_bus_update_realloc_range(struct pci_bus *bus)
+{
+	struct pci_dev *dev;
+	struct pci_bus *parent = bus->parent;
+	int idx;
+
+	list_for_each_entry(dev, &bus->devices, bus_list)
+		if (dev->subordinate)
+			pci_bus_update_realloc_range(dev->subordinate);
+
+	if (!parent || !bus->self)
+		return;
+
+	for (idx = 0; idx < PCI_BRIDGE_RESOURCE_NUM; ++idx) {
+		struct resource *immovable_range = &bus->immovable_range[idx];
+		resource_size_t window_size = resource_size(bus->resource[idx]);
+		resource_size_t realloc_start, realloc_end;
+
+		bus->realloc_range[idx].start = 0;
+		bus->realloc_range[idx].end = 0;
+
+		/* Check if there any immovable BARs under the bridge */
+		if (immovable_range->start >= immovable_range->end)
+			continue;
+
+		/* The lowest possible address where the bridge window can start */
+		realloc_start = immovable_range->end - window_size + 1;
+		/* The highest possible address where the bridge window can end */
+		realloc_end = immovable_range->start + window_size - 1;
+
+		if (realloc_start > immovable_range->start)
+			realloc_start = immovable_range->start;
+
+		if (realloc_end < immovable_range->end)
+			realloc_end = immovable_range->end;
+
+		/*
+		 * Check that realloc range doesn't intersect with hard fixed ranges
+		 * of neighboring bridges
+		 */
+		list_for_each_entry(dev, &parent->devices, bus_list) {
+			struct pci_bus *neighbor = dev->subordinate;
+			struct resource *n_imm_range;
+
+			if (!neighbor || neighbor == bus)
+				continue;
+
+			n_imm_range = &neighbor->immovable_range[idx];
+
+			if (n_imm_range->start >= n_imm_range->end)
+				continue;
+
+			if (n_imm_range->end < immovable_range->start &&
+			    n_imm_range->end > realloc_start)
+				realloc_start = n_imm_range->end;
+		}
+
+		bus->realloc_range[idx].start = realloc_start;
+		bus->realloc_range[idx].end = realloc_end;
+	}
+}
+
 /*
  * First try will not touch PCI bridge res.
  * Second and later try will clear small leaf bridge res.
@@ -1838,6 +1904,7 @@ void pci_assign_unassigned_root_bus_resources(struct pci_bus *bus)
 
 	if (pci_movable_bars_enabled()) {
 		__pci_bus_size_bridges(bus, NULL);
+		pci_bus_update_realloc_range(bus);
 		__pci_bus_assign_resources(bus, NULL, NULL);
 
 		goto dump;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index efafbf816fe6..bf6638cf2525 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -587,6 +587,12 @@ struct pci_bus {
 	 */
 	struct resource immovable_range[PCI_BRIDGE_RESOURCE_NUM];
 
+	/*
+	 * Acceptable address range, where the bridge window may reside, considering its
+	 * size, so it will cover all the fixed and immovable BARs below.
+	 */
+	struct resource realloc_range[PCI_BRIDGE_RESOURCE_NUM];
+
 	struct pci_ops	*ops;		/* Configuration access functions */
 	struct msi_controller *msi;	/* MSI controller */
 	void		*sysdata;	/* Hook for sys-specific extension */
-- 
2.21.0


  parent reply index

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-16 16:50 [PATCH v5 00/23] PCI: Allow BAR movement during hotplug Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 01/23] PCI: Fix race condition in pci_enable/disable_device() Sergey Miroshnichenko
2019-08-22 12:37   ` Marta Rybczynska
2019-09-27 21:59   ` Bjorn Helgaas
2019-09-30  8:53     ` Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 02/23] PCI: Enable bridge's I/O and MEM access for hotplugged devices Sergey Miroshnichenko
2019-09-27 22:01   ` Bjorn Helgaas
2019-08-16 16:50 ` [PATCH v5 03/23] PCI: hotplug: Add a flag for the movable BARs feature Sergey Miroshnichenko
2019-09-27 22:02   ` Bjorn Helgaas
2019-09-30  8:44     ` David Laight
2019-09-30 16:17       ` Sergey Miroshnichenko
2019-09-30 12:59     ` Sergey Miroshnichenko
2019-10-15 22:14       ` Bjorn Helgaas
2019-10-16 15:50         ` Sergey Miroshnichenko
2019-10-16 17:29           ` Bjorn Helgaas
2019-08-16 16:50 ` [PATCH v5 04/23] PCI: Define PCI-specific version of the release_child_resources() Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 05/23] PCI: hotplug: movable BARs: Fix reassigning the released bridge windows Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 06/23] PCI: hotplug: movable BARs: Recalculate all bridge windows during rescan Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 07/23] PCI: hotplug: movable BARs: Don't allow added devices to steal resources Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 08/23] PCI: Include fixed and immovable BARs into the bus size calculating Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 09/23] PCI: Prohibit assigning BARs and bridge windows to non-direct parents Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 10/23] PCI: hotplug: movable BARs: Try to assign unassigned resources only once Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 11/23] PCI: hotplug: movable BARs: Calculate immovable parts of bridge windows Sergey Miroshnichenko
2019-08-16 16:50 ` Sergey Miroshnichenko [this message]
2019-08-16 16:50 ` [PATCH v5 13/23] PCI: Make sure bridge windows include their fixed BARs Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 14/23] PCI: Fix assigning the fixed prefetchable resources Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 15/23] PCI: hotplug: movable BARs: Assign fixed and immovable BARs before others Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 16/23] PCI: hotplug: movable BARs: Don't reserve IO/mem bus space Sergey Miroshnichenko
2019-09-04  5:42   ` Oliver O'Halloran
2019-09-04 11:22     ` Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 17/23] powerpc/pci: Fix crash with enabled movable BARs Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 18/23] powerpc/pci: Handle BAR movement Sergey Miroshnichenko
2019-09-04  5:37   ` Oliver O'Halloran
2019-09-06 16:24     ` Sergey Miroshnichenko
2019-09-09 14:02       ` Oliver O'Halloran
2019-08-16 16:50 ` [PATCH v5 19/23] PCI: hotplug: Configure MPS for hot-added bridges during bus rescan Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 20/23] PCI: hotplug: movable BARs: Enable the feature by default Sergey Miroshnichenko
2019-08-16 16:50 ` [PATCH v5 21/23] nvme-pci: Handle movable BARs Sergey Miroshnichenko
2019-08-16 16:51 ` [PATCH v5 22/23] PCI/portdrv: Declare support of " Sergey Miroshnichenko
2019-08-16 16:51 ` [PATCH v5 23/23] PCI: pciehp: movable BARs: Trigger a domain rescan on hp events Sergey Miroshnichenko

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