From 5f50867b4f1938ab80d249206efbec37bba48c39 Mon Sep 17 00:00:00 2001 From: Haren Myneni Date: Thu, 22 Jun 2006 23:35:10 -0700 Subject: [PATCH] [POWERPC] kdump: Reserve the existing TCE mappings left by the first kernel During kdump boot, noticed some machines checkstop on dma protection fault for ongoing DMA left in the first kernel. Instead of initializing TCE entries in iommu_init() for the kdump boot, this patch fixes this issue by walking through the each TCE table and checks whether the entries are in use by the first kernel. If so, reserve those entries by setting the corresponding bit in tbl->it_map such that these entries will not be available for the kdump boot. However it could be possible that all TCE entries might be used up due to the driver bug that does continuous mapping. My observation is around 1700 TCE entries are used on some systems (Ex: P4) at some point of time during kdump boot and saving dump (either write into the disk or sending to remote machine). Hence, this patch will make sure that minimum of 2048 entries will be available such that kdump boot could be successful in some cases. Signed-off-by: Haren Myneni Acked-by: Olof Johansson Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/iommu.c | 30 +++++++++++++++++++++++ arch/powerpc/platforms/pseries/iommu.c | 33 ++++++++++++++++++++++++++ include/asm-powerpc/kdump.h | 2 ++ include/asm-powerpc/machdep.h | 2 ++ 4 files changed, 67 insertions(+) diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c index 7cb77c20fc5d..3d677ac99659 100644 --- a/arch/powerpc/kernel/iommu.c +++ b/arch/powerpc/kernel/iommu.c @@ -38,6 +38,7 @@ #include #include #include +#include #define DBG(...) @@ -440,8 +441,37 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid) tbl->it_largehint = tbl->it_halfpoint; spin_lock_init(&tbl->it_lock); +#ifdef CONFIG_CRASH_DUMP + if (ppc_md.tce_get) { + unsigned long index, tceval; + unsigned long tcecount = 0; + + /* + * Reserve the existing mappings left by the first kernel. + */ + for (index = 0; index < tbl->it_size; index++) { + tceval = ppc_md.tce_get(tbl, index + tbl->it_offset); + /* + * Freed TCE entry contains 0x7fffffffffffffff on JS20 + */ + if (tceval && (tceval != 0x7fffffffffffffffUL)) { + __set_bit(index, tbl->it_map); + tcecount++; + } + } + if ((tbl->it_size - tcecount) < KDUMP_MIN_TCE_ENTRIES) { + printk(KERN_WARNING "TCE table is full; "); + printk(KERN_WARNING "freeing %d entries for the kdump boot\n", + KDUMP_MIN_TCE_ENTRIES); + for (index = tbl->it_size - KDUMP_MIN_TCE_ENTRIES; + index < tbl->it_size; index++) + __clear_bit(index, tbl->it_map); + } + } +#else /* Clear the hardware table in case firmware left allocations in it */ ppc_md.tce_free(tbl, tbl->it_offset, tbl->it_size); +#endif if (!welcomed) { printk(KERN_INFO "IOMMU table initialized, virtual merging %s\n", diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index d03a8b078f9d..8cfb5706790e 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -92,6 +92,15 @@ static void tce_free_pSeries(struct iommu_table *tbl, long index, long npages) *(tcep++) = 0; } +static unsigned long tce_get_pseries(struct iommu_table *tbl, long index) +{ + u64 *tcep; + + index <<= TCE_PAGE_FACTOR; + tcep = ((u64 *)tbl->it_base) + index; + + return *tcep; +} static void tce_build_pSeriesLP(struct iommu_table *tbl, long tcenum, long npages, unsigned long uaddr, @@ -235,6 +244,25 @@ static void tce_freemulti_pSeriesLP(struct iommu_table *tbl, long tcenum, long n } } +static unsigned long tce_get_pSeriesLP(struct iommu_table *tbl, long tcenum) +{ + u64 rc; + unsigned long tce_ret; + + tcenum <<= TCE_PAGE_FACTOR; + rc = plpar_tce_get((u64)tbl->it_index, (u64)tcenum << 12, &tce_ret); + + if (rc && printk_ratelimit()) { + printk("tce_get_pSeriesLP: plpar_tce_get failed. rc=%ld\n", + rc); + printk("\tindex = 0x%lx\n", (u64)tbl->it_index); + printk("\ttcenum = 0x%lx\n", (u64)tcenum); + show_stack(current, (unsigned long *)__get_SP()); + } + + return tce_ret; +} + static void iommu_table_setparms(struct pci_controller *phb, struct device_node *dn, struct iommu_table *tbl) @@ -254,7 +282,10 @@ static void iommu_table_setparms(struct pci_controller *phb, } tbl->it_base = (unsigned long)__va(*basep); + +#ifndef CONFIG_CRASH_DUMP memset((void *)tbl->it_base, 0, *sizep); +#endif tbl->it_busno = phb->bus->number; @@ -560,11 +591,13 @@ void iommu_init_early_pSeries(void) ppc_md.tce_build = tce_build_pSeriesLP; ppc_md.tce_free = tce_free_pSeriesLP; } + ppc_md.tce_get = tce_get_pSeriesLP; ppc_md.iommu_bus_setup = iommu_bus_setup_pSeriesLP; ppc_md.iommu_dev_setup = iommu_dev_setup_pSeriesLP; } else { ppc_md.tce_build = tce_build_pSeries; ppc_md.tce_free = tce_free_pSeries; + ppc_md.tce_get = tce_get_pseries; ppc_md.iommu_bus_setup = iommu_bus_setup_pSeries; ppc_md.iommu_dev_setup = iommu_dev_setup_pSeries; } diff --git a/include/asm-powerpc/kdump.h b/include/asm-powerpc/kdump.h index 5a5c3b5ab1e0..dc1574c945f8 100644 --- a/include/asm-powerpc/kdump.h +++ b/include/asm-powerpc/kdump.h @@ -15,6 +15,8 @@ #define KDUMP_TRAMPOLINE_START 0x0100 #define KDUMP_TRAMPOLINE_END 0x3000 +#define KDUMP_MIN_TCE_ENTRIES 2048 + #else /* !CONFIG_CRASH_DUMP */ #define PHYSICAL_START 0x0 diff --git a/include/asm-powerpc/machdep.h b/include/asm-powerpc/machdep.h index 73db1f71329d..eba133d149a7 100644 --- a/include/asm-powerpc/machdep.h +++ b/include/asm-powerpc/machdep.h @@ -81,6 +81,8 @@ struct machdep_calls { void (*tce_free)(struct iommu_table *tbl, long index, long npages); + unsigned long (*tce_get)(struct iommu_table *tbl, + long index); void (*tce_flush)(struct iommu_table *tbl); void (*iommu_dev_setup)(struct pci_dev *dev); void (*iommu_bus_setup)(struct pci_bus *bus);