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Subject[PATCH 07/10] iommu/vt-d: enable kdump support in iommu module
Date
Modify the operation of the following functions when called during crash dump:
device_to_domain_id
get_domain_for_dev
init_dmars
intel_iommu_init

Bill Sumner:
Original version.

Zhenhua:
Minor change, change some function name, add spin_lock_irqsave.

Signed-off-by: Bill Sumner <billsumnerlinux@gmail.com>
Signed-off-by: Li, Zhen-Hua <zhen-hual@hp.com>
---
drivers/iommu/intel-iommu.c | 142 ++++++++++++++++++++++++++++++++++++++------
1 file changed, 125 insertions(+), 17 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 9b2f725..4837ce5 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -907,6 +907,11 @@ static struct context_entry * device_to_context_entry(struct intel_iommu *iommu,
set_root_value(root, phy_addr);
set_root_present(root);
__iommu_flush_cache(iommu, root, sizeof(*root));
+
+#ifdef CONFIG_CRASH_DUMP
+ if (is_kdump_kernel())
+ __iommu_update_old_root_entry(iommu, bus);
+#endif
}
spin_unlock_irqrestore(&iommu->lock, flags);
return &context[devfn];
@@ -958,7 +963,8 @@ static void free_context_table(struct intel_iommu *iommu)

spin_lock_irqsave(&iommu->lock, flags);
if (!iommu->root_entry) {
- goto out;
+ spin_unlock_irqrestore(&iommu->lock, flags);
+ return;
}
for (i = 0; i < ROOT_ENTRY_NR; i++) {
root = &iommu->root_entry[i];
@@ -966,10 +972,26 @@ static void free_context_table(struct intel_iommu *iommu)
if (context)
free_pgtable_page(context);
}
- free_pgtable_page(iommu->root_entry);
- iommu->root_entry = NULL;
-out:
+
+#ifdef CONFIG_CRASH_DUMP
+ if (is_kdump_kernel()) {
+ iommu->root_entry_old_phys = 0;
+ root = iommu->root_entry;
+ iommu->root_entry = NULL;
+ } else {
+#endif
+ free_pgtable_page(iommu->root_entry);
+ iommu->root_entry = NULL;
+#ifdef CONFIG_CRASH_DUMP
+ }
+#endif
+
spin_unlock_irqrestore(&iommu->lock, flags);
+
+#ifdef CONFIG_CRASH_DUMP
+ if (is_kdump_kernel())
+ iounmap(root);
+#endif
}

static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain,
@@ -2381,6 +2403,9 @@ static struct dmar_domain *get_domain_for_dev(struct device *dev, int gaw)
unsigned long flags;
u8 bus, devfn;
int did = -1; /* Default to "no domain_id supplied" */
+#ifdef CONFIG_CRASH_DUMP
+ struct domain_values_entry *dve = NULL;
+#endif /* CONFIG_CRASH_DUMP */

domain = find_domain(dev);
if (domain)
@@ -2414,6 +2439,24 @@ static struct dmar_domain *get_domain_for_dev(struct device *dev, int gaw)
domain = alloc_domain(0);
if (!domain)
return NULL;
+
+#ifdef CONFIG_CRASH_DUMP
+ if (is_kdump_kernel()) {
+ /*
+ * if this device had a did in the old kernel
+ * use its values instead of generating new ones
+ */
+ did = device_to_domain_id(iommu, bus, devfn);
+ if (did > 0 || (did == 0 && !cap_caching_mode(iommu->cap)))
+ dve = intel_iommu_did_to_domain_values_entry(did,
+ iommu);
+ if (dve)
+ gaw = dve->gaw;
+ else
+ did = -1;
+ }
+#endif /* CONFIG_CRASH_DUMP */
+
domain->id = iommu_attach_domain(domain, iommu, did);
if (domain->id < 0) {
free_domain_mem(domain);
@@ -2425,6 +2468,18 @@ static struct dmar_domain *get_domain_for_dev(struct device *dev, int gaw)
return NULL;
}

+#ifdef CONFIG_CRASH_DUMP
+ if (is_kdump_kernel() && dve) {
+
+ if (domain->pgd)
+ free_pgtable_page(domain->pgd);
+
+ domain->pgd = dve->pgd;
+
+ copy_reserved_iova(&dve->iovad, &domain->iovad);
+ }
+#endif /* CONFIG_CRASH_DUMP */
+
/* register PCI DMA alias device */
if (dev_is_pci(dev)) {
tmp = dmar_insert_dev_info(iommu, PCI_BUS_NUM(dma_alias),
@@ -2948,14 +3003,35 @@ static int __init init_dmars(void)
if (ret)
goto free_iommu;

- /*
- * TBD:
- * we could share the same root & context tables
- * among all IOMMU's. Need to Split it later.
- */
- ret = iommu_alloc_root_entry(iommu);
- if (ret)
- goto free_iommu;
+#ifdef CONFIG_CRASH_DUMP
+ if (is_kdump_kernel()) {
+ pr_info("IOMMU Copying translate tables from panicked kernel\n");
+ ret = intel_iommu_copy_translation_tables(drhd,
+ g_num_of_iommus);
+ if (ret) {
+ pr_err("IOMMU: Copy translate tables failed\n");
+
+ /* Best to stop trying */
+ goto free_iommu;
+ }
+ pr_info("IOMMU: root_cache:0x%12.12llx phys:0x%12.12llx\n",
+ (u64)iommu->root_entry,
+ (u64)iommu->root_entry_old_phys);
+ intel_iommu_get_dids_from_old_kernel(iommu);
+ } else {
+#endif /* CONFIG_CRASH_DUMP */
+ /*
+ * TBD:
+ * we could share the same root & context tables
+ * among all IOMMU's. Need to Split it later.
+ */
+ ret = iommu_alloc_root_entry(iommu);
+ if (ret)
+ goto free_iommu;
+#ifdef CONFIG_CRASH_DUMP
+ }
+#endif
+
if (!ecap_pass_through(iommu->ecap))
hw_pass_through = 0;
}
@@ -2972,6 +3048,16 @@ static int __init init_dmars(void)

check_tylersburg_isoch();

+#ifdef CONFIG_CRASH_DUMP
+ /*
+ * In the crashdump kernel: Skip setting-up new domains for
+ * si, rmrr, and the isa bus on the expectation that these
+ * translations were copied from the old kernel.
+ */
+ if (is_kdump_kernel())
+ goto skip_new_domains_for_si_rmrr_isa;
+#endif /* CONFIG_CRASH_DUMP */
+
/*
* If pass through is not set or not enabled, setup context entries for
* identity mappings for rmrr, gfx, and isa and may fall back to static
@@ -3012,6 +3098,10 @@ static int __init init_dmars(void)

iommu_prepare_isa();

+#ifdef CONFIG_CRASH_DUMP
+skip_new_domains_for_si_rmrr_isa:;
+#endif /* CONFIG_CRASH_DUMP */
+
/*
* for each drhd
* enable fault log
@@ -3040,7 +3130,15 @@ static int __init init_dmars(void)

iommu->flush.flush_context(iommu, 0, 0, 0, DMA_CCMD_GLOBAL_INVL);
iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_GLOBAL_FLUSH);
- iommu_enable_translation(iommu);
+
+#ifdef CONFIG_CRASH_DUMP
+ if (is_kdump_kernel()) {
+ if (!(iommu->gcmd & DMA_GCMD_TE))
+ iommu_enable_translation(iommu);
+ } else
+#endif
+ iommu_enable_translation(iommu);
+
iommu_disable_protect_mem_regions(iommu);
}

@@ -4351,12 +4449,22 @@ int __init intel_iommu_init(void)
goto out_free_dmar;
}

+#ifdef CONFIG_CRASH_DUMP
/*
- * Disable translation if already enabled prior to OS handover.
+ * If (This is the crash kernel)
+ * Set: copy iommu translate tables from old kernel
+ * Skip disabling the iommu hardware translations
*/
- for_each_active_iommu(iommu, drhd)
- if (iommu->gcmd & DMA_GCMD_TE)
- iommu_disable_translation(iommu);
+ if (is_kdump_kernel()) {
+ pr_info("IOMMU Skip disabling iommu hardware translations\n");
+ } else
+#endif /* CONFIG_CRASH_DUMP */
+ /*
+ * Disable translation if already enabled prior to OS handover.
+ */
+ for_each_active_iommu(iommu, drhd)
+ if (iommu->gcmd & DMA_GCMD_TE)
+ iommu_disable_translation(iommu);

if (dmar_dev_scope_init() < 0) {
if (force_on)
--
2.0.0-rc0


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