calgary iommu: use the first kernels TCE tables in kdump

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 get 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 instead 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.

Signed-off-by: Chandru Siddalingappa <chandru@in.ibm.com>
Acked-by: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 87 insertions, 6 deletions

diff --git a/arch/x86/kernel/pci-calgary_64.c b/arch/x86/kernel/pci-calgary_64.c
index 151f2d171f7c..19e7fc7c2c4f 100644
--- a/arch/x86/kernel/pci-calgary_64.c
+++ b/arch/x86/kernel/pci-calgary_64.c
@@ -29,6 +29,7 @@
 #include <linux/mm.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>
+#include <linux/crash_dump.h>
 #include <linux/dma-mapping.h>
 #include <linux/bitops.h>
 #include <linux/pci_ids.h>
@@ -167,6 +168,8 @@ static void calgary_dump_error_regs(struct iommu_table *tbl);
 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 void calgary_init_bitmap_from_tce_table(struct iommu_table *tbl);
+static void get_tce_space_from_tar(void);
 
 static struct cal_chipset_ops calgary_chip_ops = {
         .handle_quirks = calgary_handle_quirks,
@@ -830,7 +833,11 @@ static int __init calgary_setup_tar(struct pci_dev *dev, void __iomem *bbar)
 
         tbl = pci_iommu(dev->bus);
         tbl->it_base = (unsigned long)bus_info[dev->bus->number].tce_space;
-        tce_free(tbl, 0, tbl->it_size);
+
+        if (is_kdump_kernel())
+                calgary_init_bitmap_from_tce_table(tbl);
+        else
+                tce_free(tbl, 0, tbl->it_size);
 
         if (is_calgary(dev->device))
                 tbl->chip_ops = &calgary_chip_ops;
@@ -1209,6 +1216,10 @@ static int __init calgary_init(void)
         if (ret)
                 return ret;
 
+        /* Purely for kdump kernel case */
+        if (is_kdump_kernel())
+                get_tce_space_from_tar();
+
         do {
                 dev = pci_get_device(PCI_VENDOR_ID_IBM, PCI_ANY_ID, dev);
                 if (!dev)
@@ -1339,6 +1350,61 @@ static int __init calgary_bus_has_devices(int bus, unsigned short pci_dev)
         return (val != 0xffffffff);
 }
 
+/*
+ * calgary_init_bitmap_from_tce_table():
+ * Funtion for kdump case. In the second/kdump kernel initialize
+ * the bitmap based on the tce table entries obtained from first kernel
+ */
+static void calgary_init_bitmap_from_tce_table(struct iommu_table *tbl)
+{
+        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++;
+        }
+}
+
+/*
+ * get_tce_space_from_tar():
+ * Function for kdump case. Get the tce tables from first kernel
+ * by reading the contents of the base adress register of calgary iommu
+ */
+static void get_tce_space_from_tar()
+{
+        int bus;
+        void __iomem *target;
+        unsigned long tce_space;
+
+        for (bus = 0; bus < MAX_PHB_BUS_NUM; bus++) {
+                struct calgary_bus_info *info = &bus_info[bus];
+                unsigned short pci_device;
+                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;
+
+                        tce_space = tce_space & (~specified_table_size);
+                        info->tce_space = (u64 *)__va(tce_space);
+                }
+        }
+        return;
+}
+
 void __init detect_calgary(void)
 {
         int bus;
@@ -1394,7 +1460,8 @@ void __init detect_calgary(void)
                 return;
         }
 
-        specified_table_size = determine_tce_table_size(max_pfn * PAGE_SIZE);
+        specified_table_size = determine_tce_table_size((is_kdump_kernel() ?
+                                        saved_max_pfn : max_pfn) * PAGE_SIZE);
 
         for (bus = 0; bus < MAX_PHB_BUS_NUM; bus++) {
                 struct calgary_bus_info *info = &bus_info[bus];
@@ -1412,10 +1479,16 @@ 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 it is kdump kernel, find and use tce tables
+                         * from first kernel, else allocate tce tables here
+                         */
+                        if (!is_kdump_kernel()) {
+                                tbl = alloc_tce_table();
+                                if (!tbl)
+                                        goto cleanup;
+                                info->tce_space = tbl;
+                        }
                         calgary_found = 1;
                 }
         }
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 22c7ac5cd80c..6cd39a927e1f 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -22,5 +22,13 @@ extern struct proc_dir_entry *proc_vmcore;
 
 #define vmcore_elf_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
 
+static inline int is_kdump_kernel(void)
+{
+        return (elfcorehdr_addr != ELFCORE_ADDR_MAX) ? 1 : 0;
+}
+#else /* !CONFIG_CRASH_DUMP */
+static inline int is_kdump_kernel(void) { return 0; }
 #endif /* CONFIG_CRASH_DUMP */
+
+extern unsigned long saved_max_pfn;
 #endif /* LINUX_CRASHDUMP_H */