[patch 2/2] x2apic: fix using early fixmap mapping for DMAR table parsing

From: Suresh Siddha
Date: Tue Sep 02 2008 - 19:53:23 EST


From: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
Subject: x2apic, dmar: fix using early fixmap mapping for DMAR table parsing

Very early detection of the DMAR tables will setup fixmap mapping. For
parsing these tables later (while enabling dma and/or interrupt remapping),
early fixmap mapping shouldn't be used. Fix it by calling table detection
routines again, which will call generic apci_get_table() for setting up
the correct mapping.

Signed-off-by: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
Signed-off-by: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
---

Index: tip/drivers/pci/dmar.c
===================================================================
--- tip.orig/drivers/pci/dmar.c 2008-09-02 16:04:04.000000000 -0700
+++ tip/drivers/pci/dmar.c 2008-09-02 16:41:31.000000000 -0700
@@ -289,6 +289,24 @@
}
}

+/**
+ * dmar_table_detect - checks to see if the platform supports DMAR devices
+ */
+static int __init dmar_table_detect(void)
+{
+ acpi_status status = AE_OK;
+
+ /* if we could find DMAR table, then there are DMAR devices */
+ status = acpi_get_table(ACPI_SIG_DMAR, 0,
+ (struct acpi_table_header **)&dmar_tbl);
+
+ if (ACPI_SUCCESS(status) && !dmar_tbl) {
+ printk (KERN_WARNING PREFIX "Unable to map DMAR\n");
+ status = AE_NOT_FOUND;
+ }
+
+ return (ACPI_SUCCESS(status) ? 1 : 0);
+}

/**
* parse_dmar_table - parses the DMA reporting table
@@ -300,6 +318,12 @@
struct acpi_dmar_header *entry_header;
int ret = 0;

+ /*
+ * Do it again, earlier dmar_tbl mapping could be mapped with
+ * fixed map.
+ */
+ dmar_table_detect();
+
dmar = (struct acpi_table_dmar *)dmar_tbl;
if (!dmar)
return -ENODEV;
@@ -430,30 +454,11 @@
return 0;
}

-/**
- * early_dmar_detect - checks to see if the platform supports DMAR devices
- */
-int __init early_dmar_detect(void)
-{
- acpi_status status = AE_OK;
-
- /* if we could find DMAR table, then there are DMAR devices */
- status = acpi_get_table(ACPI_SIG_DMAR, 0,
- (struct acpi_table_header **)&dmar_tbl);
-
- if (ACPI_SUCCESS(status) && !dmar_tbl) {
- printk (KERN_WARNING PREFIX "Unable to map DMAR\n");
- status = AE_NOT_FOUND;
- }
-
- return (ACPI_SUCCESS(status) ? 1 : 0);
-}
-
void __init detect_intel_iommu(void)
{
int ret;

- ret = early_dmar_detect();
+ ret = dmar_table_detect();

#ifdef CONFIG_DMAR
{
@@ -479,14 +484,16 @@
" x2apic support\n");

dmar_disabled = 1;
- return;
+ goto end;
}

if (ret && !no_iommu && !iommu_detected && !swiotlb &&
!dmar_disabled)
iommu_detected = 1;
}
+end:
#endif
+ dmar_tbl = NULL;
}


Index: tip/include/linux/dmar.h
===================================================================
--- tip.orig/include/linux/dmar.h 2008-09-02 16:04:04.000000000 -0700
+++ tip/include/linux/dmar.h 2008-09-02 16:40:40.000000000 -0700
@@ -45,7 +45,6 @@
list_for_each_entry(drhd, &dmar_drhd_units, list)

extern int dmar_table_init(void);
-extern int early_dmar_detect(void);
extern int dmar_dev_scope_init(void);

/* Intel IOMMU detection */

--

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