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SubjectRe: [PATCH v11 07/10] iommu/vt-d: enable kdump support in iommu module
On 05/11/15 at 05:52pm, Li, Zhen-Hua wrote:
> Modify the operation of the following functions when called during crash dump:
> iommu_context_addr
> 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 | 95 +++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 83 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 28c3c64..91545bf 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -397,6 +397,7 @@ 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.
> @@ -794,6 +795,9 @@ static inline struct context_entry *iommu_context_addr(struct intel_iommu *iommu
> phy_addr = virt_to_phys((void *)context);
> *entry = phy_addr | 1;
> __iommu_flush_cache(iommu, entry, sizeof(*entry));
> +
> + if (iommu->pre_enabled_trans)
> + __iommu_update_old_root_entry(iommu, bus);
> }
> return &context[devfn];
> }
> @@ -887,13 +891,15 @@ static void clear_context_table(struct intel_iommu *iommu, u8 bus, u8 devfn)
>
> static void free_context_table(struct intel_iommu *iommu)
> {
> + struct root_entry *root = NULL;
> int i;
> unsigned long flags;
> struct context_entry *context;
>
> 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++) {
> context = iommu_context_addr(iommu, i, 0, 0);
> @@ -908,10 +914,23 @@ static void free_context_table(struct intel_iommu *iommu)
> 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,
> @@ -2333,6 +2352,7 @@ 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)
> @@ -2366,6 +2386,20 @@ 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);
> @@ -2897,6 +2931,7 @@ 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;
>
> @@ -2904,14 +2939,30 @@ 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;
> }
> @@ -2929,6 +2980,14 @@ static int __init init_dmars(void)
> check_tylersburg_isoch();
>
> /*
> + * In the second kernel: Skip setting-up new domains for

Use kexec kernel instead of second kernel is better because there's no context
reader will be confused.

> + * 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.
> @@ -2968,6 +3027,8 @@ static int __init init_dmars(void)
>
> iommu_prepare_isa();
>
> +skip_new_domains_for_si_rmrr_isa:;
> +
> /*
> * for each drhd
> * enable fault log
> @@ -2996,7 +3057,13 @@ 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);
> }
>
> @@ -4282,11 +4349,14 @@ 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);
> + */

Above commented out code is useless?

>
> if (dmar_dev_scope_init() < 0) {
> if (force_on)
> @@ -5106,5 +5176,6 @@ 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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