Re: [PATCH v1 2/3] x86/PCI: trim _CRS windows when they conflict with previous reservations

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Bjorn Helgaas wrote:
Yanko's GA-MA78GM-S2H (BIOS F11) reports a host bridge window that overlaps
system memory:

    PCI window: [mem 0xcff00000-0x10ed0ffff]
    System RAM: [mem 0x100000000-0x22fffffff]

We can be pretty confident that the System RAM region is correct (if it
were wrong, we'd crash as soon as we tried to use any memory in that area),
so this patch tries to correct the PCI window by trimming it so it doesn't
conflict with any previous reservations.

Though I might misunderstand something, it looks Yanko's machine specific
workaround. I'm wondering if trimming _CRS is a generic workaround for
broken _CRS machine.

How about doing this when GA-MA78GM-S2H (BIOS F11) (and known machines
that have the same problem) is detected? Or how about switching nocrs
mode if the problem (resource conflict) is detected?

Thanks,
Kenji Kaneshige



http://bugzilla.kernel.org/show_bug.cgi?id=15480

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@xxxxxx>
Reported-by: Yanko Kaneti <yaneti@xxxxxxxxxxx>
---

 arch/x86/pci/acpi.c |   48 +++++++++++++++++++++++++++++++++++-------------
 1 files changed, 35 insertions(+), 13 deletions(-)


diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 6e22454..d255ce8 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -114,11 +114,19 @@ align_resource(struct acpi_device *bridge, struct resource *res)
 	}
 }
+static bool
+resource_contains(struct resource *res, resource_size_t n)
+{
+	if (n < res->start || n > res->end)
+		return false;
+	return true;
+}
+
 static acpi_status
 setup_resource(struct acpi_resource *acpi_res, void *data)
 {
 	struct pci_root_info *info = data;
-	struct resource *res;
+	struct resource *res, *conflict;
 	struct acpi_resource_address64 addr;
 	acpi_status status;
 	unsigned long flags;
@@ -157,21 +165,35 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
 		return AE_OK;
 	}
- if (insert_resource(root, res)) {
+	conflict = insert_resource_conflict(root, res);
+	while (conflict) {
 		dev_err(&info->bridge->dev,
-			"can't allocate host bridge window %pR\n", res);
-	} else {
-		pci_bus_add_resource(info->bus, res, 0);
-		info->res_num++;
-		if (addr.translation_offset)
-			dev_info(&info->bridge->dev, "host bridge window %pR "
-				 "(PCI address [%#llx-%#llx])\n",
-				 res, res->start - addr.translation_offset,
-				 res->end - addr.translation_offset);
+		        "host bridge window %pR conflicts with %s %pR\n",
+			res, conflict->name, conflict);
+
+		if (resource_contains(res, conflict->end))
+			res->start = conflict->end + 1;
+		else if (resource_contains(res, conflict->start))
+			res->end = conflict->start - 1;
 		else
-			dev_info(&info->bridge->dev,
-				 "host bridge window %pR\n", res);
+			return AE_OK;
+
+		if (res->start >= res->end)
+			return AE_OK;
+
+		conflict = insert_resource_conflict(root, res);
 	}
+
+	pci_bus_add_resource(info->bus, res, 0);
+	info->res_num++;
+	if (addr.translation_offset)
+		dev_info(&info->bridge->dev, "host bridge window %pR "
+			 "(PCI address [%#llx-%#llx])\n",
+			 res, res->start - addr.translation_offset,
+			 res->end - addr.translation_offset);
+	else
+		dev_info(&info->bridge->dev,
+			 "host bridge window %pR\n", res);
 	return AE_OK;
 }
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