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Subject[PATCH v10 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_context_entry
free_context_table
get_domain_for_dev
init_dmars
intel_iommu_init

Bill Sumner:
Original version.

Zhenhua:
The name of new calling functions.
Do not disable and re-enable TE in kdump kernel.
Use the did and gaw from old context entry;

Signed-off-by: Bill Sumner <billsumnerlinux@gmail.com>
Signed-off-by: Li, Zhen-Hua <zhen-hual@hp.com>
---
drivers/iommu/intel-iommu.c | 94 +++++++++++++++++++++++++++++++++++++++------
1 file changed, 82 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 78c1d65..3d4ea43 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -399,6 +399,7 @@ static int copy_root_entry_table(struct intel_iommu *iommu);
static int intel_iommu_load_translation_tables(struct intel_iommu *iommu);

static void iommu_check_pre_te_status(struct intel_iommu *iommu);
+static u8 g_translation_pre_enabled;

/*
* This domain is a statically identity mapping domain.
@@ -839,6 +840,9 @@ 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));
+
+ if (iommu->pre_enabled_trans)
+ __iommu_update_old_root_entry(iommu, bus);
}
spin_unlock_irqrestore(&iommu->lock, flags);
return &context[devfn];
@@ -890,7 +894,8 @@ 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];
@@ -898,10 +903,23 @@ static void free_context_table(struct intel_iommu *iommu)
if (context)
free_pgtable_page(context);
}
+
+ if (iommu->pre_enabled_trans) {
+ iommu->root_entry_old_phys = 0;
+ root = iommu->root_entry_old_virt;
+ iommu->root_entry_old_virt = NULL;
+ }
+
free_pgtable_page(iommu->root_entry);
iommu->root_entry = NULL;
-out:
+
spin_unlock_irqrestore(&iommu->lock, flags);
+
+ /* We put this out of spin_unlock is because iounmap() may
+ * cause error if surrounded by spin_lock and unlock;
+ */
+ if (iommu->pre_enabled_trans)
+ iounmap(root);
}

static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain,
@@ -2319,6 +2337,7 @@ 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" */
+ struct context_entry *ce = NULL;

domain = find_domain(dev);
if (domain)
@@ -2352,6 +2371,20 @@ static struct dmar_domain *get_domain_for_dev(struct device *dev, int gaw)
domain = alloc_domain(0);
if (!domain)
return NULL;
+
+ if (iommu->pre_enabled_trans) {
+ /*
+ * if this device had a did in the old kernel
+ * use its values instead of generating new ones
+ */
+ ce = device_to_existing_context_entry(iommu, bus, devfn);
+
+ if (ce) {
+ did = context_domain_id(ce);
+ gaw = agaw_to_width(context_address_width(ce));
+ }
+ }
+
domain->id = iommu_attach_domain_with_id(domain, iommu, did);
if (domain->id < 0) {
free_domain_mem(domain);
@@ -2879,6 +2912,7 @@ static int __init init_dmars(void)
goto free_g_iommus;
}

+ g_translation_pre_enabled = 0; /* To know whether to skip RMRR */
for_each_active_iommu(iommu, drhd) {
g_iommus[iommu->seq_id] = iommu;

@@ -2886,14 +2920,30 @@ 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;
+ iommu_check_pre_te_status(iommu);
+ if (iommu->pre_enabled_trans) {
+ pr_info("IOMMU Copying translate tables from panicked kernel\n");
+ ret = intel_iommu_load_translation_tables(iommu);
+ 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);
+ } else {
+ /*
+ * 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;
+ }
+
if (!ecap_pass_through(iommu->ecap))
hw_pass_through = 0;
}
@@ -2911,6 +2961,14 @@ static int __init init_dmars(void)
check_tylersburg_isoch();

/*
+ * In the second 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 (g_translation_pre_enabled)
+ goto skip_new_domains_for_si_rmrr_isa;
+
+ /*
* 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
* identity mapping if iommu_identity_mapping is set.
@@ -2950,6 +3008,8 @@ static int __init init_dmars(void)

iommu_prepare_isa();

+skip_new_domains_for_si_rmrr_isa:;
+
/*
* for each drhd
* enable fault log
@@ -2978,7 +3038,13 @@ 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);
+
+ if (iommu->pre_enabled_trans) {
+ if (!(iommu->gcmd & DMA_GCMD_TE))
+ iommu_enable_translation(iommu);
+ } else
+ iommu_enable_translation(iommu);
+
iommu_disable_protect_mem_regions(iommu);
}

@@ -4264,11 +4330,14 @@ int __init intel_iommu_init(void)
}

/*
- * Disable translation if already enabled prior to OS handover.
+ * We do not need to disable translation if already enabled prior
+ * to OS handover. Because we will try to copy old tables;
*/
+ /*
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)
@@ -5090,5 +5159,6 @@ static void iommu_check_pre_te_status(struct intel_iommu *iommu)
if (sts & DMA_GSTS_TES) {
pr_info("Translation is enabled prior to OS.\n");
iommu->pre_enabled_trans = 1;
+ g_translation_pre_enabled = 1;
}
}
--
2.0.0-rc0


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