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Subject[RFC] [Patch] calgary iommu: Use the first kernel's tce tables in kdump
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kdump kernel fails to boot with calgary iommu and aacraid driver on a
x366 box. The ongoing dma's of aacraid from the first kernel continue
to exist until the driver is loaded in the kdump kernel. Calgary is
initialized prior to aacraid and creation of new tce tables causes wrong
dma's to occur.

Here we try to grab the tce tables of the first kernel in kdump kernel
and use them. While in the kdump kernel we do not allocate new tce
tables but rather read the base address register contents of calgary
iommu and use the tables that the registers point to. With these changes
the kdump kernel and hence aacraid now boots normally.

Another point that came when talking with Vivek was to reserve part of
the tce table space in first kernel for use in the kdump kernel.

Signed-off-by: Chandru S <chandru@in.ibm.com>
---

--- linux-2.6.23-rc9/arch/x86_64/kernel/pci-calgary.c.orig
2007-10-09 23:39:22.000000000 +0530
+++ linux-2.6.23-rc9/arch/x86_64/kernel/pci-calgary.c 2007-10-10
01:25:53.000000000 +0530
@@ -35,6 +35,7 @@
#include <linux/pci_ids.h>
#include <linux/pci.h>
#include <linux/delay.h>
+#include <linux/bootmem.h>
#include <asm/iommu.h>
#include <asm/calgary.h>
#include <asm/tce.h>
@@ -165,6 +166,7 @@ static void calgary_dump_error_regs(stru
static void calioc2_handle_quirks(struct iommu_table *tbl, struct
pci_dev *dev);
static void calioc2_tce_cache_blast(struct iommu_table *tbl);
static void calioc2_dump_error_regs(struct iommu_table *tbl);
+static int calgary_bus_has_devices(int , unsigned short ) __init;

static struct cal_chipset_ops calgary_chip_ops = {
.handle_quirks = calgary_handle_quirks,
@@ -819,7 +821,23 @@ static int __init calgary_setup_tar(stru

tbl = pci_iommu(dev->bus);
tbl->it_base = (unsigned
long)bus_info[dev->bus->number].tce_space;
- tce_free(tbl, 0, tbl->it_size);
+#ifdef CONFIG_CRASH_DUMP
+ if (is_kdump_kernel()){
+ u64 *tp;
+ unsigned int index;
+ tp = ((u64*)tbl->it_base);
+ for(index=0;index < tbl->it_size; index++ ){
+ if ( *tp != 0x0 )
+ set_bit(index,tbl->it_map);
+
+ tp++;
+ }
+ }
+ else
+#endif
+ {
+ tce_free(tbl, 0, tbl->it_size);
+ }

if (is_calgary(dev->device))
tbl->chip_ops = &calgary_chip_ops;
@@ -1177,6 +1195,43 @@ static int __init calgary_locate_bbars(v
}
}

+#ifdef CONFIG_CRASH_DUMP
+ /*
+ * If this is a kdump kernel, then try grabbing the tce tables
+ * from first kernel by reading the contents of the base
+ * address register of calgary iommu
+ */
+ if(is_kdump_kernel()){
+ for (bus = 0; bus < MAX_PHB_BUS_NUM; bus++) {
+ struct calgary_bus_info *info = &bus_info[bus];
+ unsigned short pci_device;
+ unsigned long tce_space;
+ u32 val;
+
+ val = read_pci_config(bus, 0, 0, 0);
+ pci_device = (val & 0xFFFF0000) >> 16;
+
+ if (!is_cal_pci_dev(pci_device))
+ continue;
+
+ if (info->translation_disabled)
+ continue;
+
+ if (calgary_bus_has_devices(bus, pci_device) ||
+ translate_empty_slots ){
+
+ target = calgary_reg(bus_info[bus].bbar,
tar_offset(bus));
+ tce_space = be64_to_cpu(readq(target));
+ tce_space = tce_space & TAR_SW_BITS;
+
+ BUG_ON(specified_table_size >
TCE_TABLE_SIZE_8M);
+
+ tce_space = tce_space &
( ~specified_table_size);
+ info->tce_space = (u64
*)__va(tce_space);
+ }
+ }
+ }
+#endif
return 0;

error:
@@ -1380,7 +1435,10 @@ void __init detect_calgary(void)
return;
}

- specified_table_size = determine_tce_table_size(end_pfn *
PAGE_SIZE);
+ if(is_kdump_kernel())
+ specified_table_size =
determine_tce_table_size(saved_max_pfn * PAGE_SIZE);
+ else
+ specified_table_size = determine_tce_table_size(end_pfn
* PAGE_SIZE);

for (bus = 0; bus < MAX_PHB_BUS_NUM; bus++) {
struct calgary_bus_info *info = &bus_info[bus];
@@ -1398,10 +1456,17 @@ void __init detect_calgary(void)

if (calgary_bus_has_devices(bus, pci_device) ||
translate_empty_slots) {
- tbl = alloc_tce_table();
- if (!tbl)
- goto cleanup;
- info->tce_space = tbl;
+ /*
+ * If this is the kdump kernel then do not allocate
+ * new tce tables, try using the tce tables from the
+ * first kernel
+ */
+ if(!is_kdump_kernel()){
+ tbl = alloc_tce_table();
+ if (!tbl)
+ goto cleanup;
+ info->tce_space = tbl;
+ }
calgary_found = 1;
}
}
--- linux-2.6.23-rc9/include/linux/bootmem.h.orig 2007-10-09
23:39:32.000000000 +0530
+++ linux-2.6.23-rc9/include/linux/bootmem.h 2007-10-09
23:26:19.000000000 +0530
@@ -21,6 +21,12 @@ extern unsigned long max_pfn;

#ifdef CONFIG_CRASH_DUMP
extern unsigned long saved_max_pfn;
+static inline int is_kdump_kernel(void)
+{
+ return reset_devices ? 1 : 0 ;
+}
+#else
+static inline is_kdump_kernel(void) { return 0; }
#endif

/*

-
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