Re: [PATCH v11 06/10] iommu/vt-d: datatypes and functions used for kdump

[Baoquan He]

On 05/11/15 at 05:52pm, Li, Zhen-Hua wrote:
> Populate it with support functions to copy iommu translation tables from
> from the panicked kernel into the kdump kernel in the event of a crash.
> 
> Functions:
>     Use old root entry table, and load the old data to root_entry as cache.
>     Malloc new context table and copy old context table to the new one.
> 
> Bill Sumner:
>     Original version, the creation of the data types and functions.
> 
> Li, Zhenhua:
>     Create new function iommu_check_pre_te_status() to check status.
>     Update the caller of context_get_* and context_put*, use context_*
>         and context_set_* for replacement.
>     Update the name of the function that loads root entry table.
>     Use new function to copy old context entry tables and page tables.
>     Use "unsigned long" for physical address.
>     Remove the functions to copy page table in Bill's version.
>     Remove usage of dve and ppap in Bill's version.
> 
> Signed-off-by: Bill Sumner <billsumnerlinux@xxxxxxxxx>
> Signed-off-by: Li, Zhen-Hua <zhen-hual@xxxxxx>
> ---
>  drivers/iommu/intel-iommu.c | 121 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/intel-iommu.h |   3 ++
>  2 files changed, 124 insertions(+)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 3a5d446..28c3c64 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -386,6 +386,18 @@ struct iommu_remapped_entry {
>  static LIST_HEAD(__iommu_remapped_mem);
>  static DEFINE_MUTEX(__iommu_mem_list_lock);
>  
> +/* ========================================================================
> + * Copy iommu translation tables from old kernel into new  kernel.
> + * Entry to this set of functions is: intel_iommu_load_translation_tables()
> + * ------------------------------------------------------------------------
> + */
> +
> +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);
> +
>  /*
>   * This domain is a statically identity mapping domain.
>   *	1. This domain creats a static 1:1 mapping to all usable memory.
> @@ -4987,3 +4999,112 @@ static void __iommu_update_old_root_entry(struct intel_iommu *iommu, int index)
>  	__iommu_flush_cache(iommu, to + start, size);
>  }
>  
> +/*
> + * Load root entry tables from old kernel.
> + */
> +static int copy_root_entry_table(struct intel_iommu *iommu)
> +{
> +	u32 bus;				/* Index: root-entry-table */
> +	struct root_entry  *re;			/* Virt(iterator: new table) */
> +	unsigned long context_old_phys;		/* Phys(context table entry) */
> +	struct context_entry *context_new_virt;	/* Virt(new context_entry) */
> +
> +	/*
> +	 * A new root entry table has been allocated ,
> +	 * we need copy re from old kernel to the new allocated one.
> +	 */
> +
> +	if (!iommu->root_entry_old_phys)
> +		return -ENOMEM;
> +
> +	for (bus = 0, re = iommu->root_entry; bus < 256; bus += 1, re += 1) {
> +		if (!root_present(re))
> +			continue;
> +
> +		context_old_phys = get_context_phys_from_root(re);
> +
> +		if (!context_old_phys)
> +			continue;
> +
> +		context_new_virt =
> +			(struct context_entry *)alloc_pgtable_page(iommu->node);
> +
> +		if (!context_new_virt)
> +			return -ENOMEM;
> +
> +		__iommu_load_from_oldmem(context_new_virt,
> +					context_old_phys,
> +					VTD_PAGE_SIZE);
> +
> +		__iommu_flush_cache(iommu, context_new_virt, VTD_PAGE_SIZE);
> +
> +		set_root_value(re, virt_to_phys(context_new_virt));
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * Interface to the "load translation tables" set of functions
> + * from mainline code.
> + */
> +static int intel_iommu_load_translation_tables(struct intel_iommu *iommu)
> +{
> +	unsigned long long q;		/* quadword scratch */
> +	int ret = 0;			/* Integer return code */
> +	unsigned long flags;
> +
> +	q = dmar_readq(iommu->reg + DMAR_RTADDR_REG);
> +	if (!q)
> +		return -1;
> +
> +	spin_lock_irqsave(&iommu->lock, flags);
> +
> +	/* Load the root-entry table from the old kernel
> +	 * foreach context_entry_table in root_entry
> +	 *   Copy each entry table from old kernel
> +	 */
> +	if (!iommu->root_entry) {
> +		iommu->root_entry =
> +			(struct root_entry *)alloc_pgtable_page(iommu->node);
> +		if (!iommu->root_entry) {
> +			spin_unlock_irqrestore(&iommu->lock, flags);
> +			return -ENOMEM;
> +		}
> +	}
> +
> +	iommu->root_entry_old_phys = q & VTD_PAGE_MASK;
> +	if (!iommu->root_entry_old_phys) {
> +		pr_err("Could not read old root entry address.");
> +		return -1;
> +	}
> +

I didn't find where you call iounmap to free mapping of
iommu->root_entry_old_phys. Am I missing anything?

> +	iommu->root_entry_old_virt = ioremap_cache(iommu->root_entry_old_phys,
> +						VTD_PAGE_SIZE);
> +	if (!iommu->root_entry_old_virt) {
> +		pr_err("Could not map the old root entry.");
> +		return -ENOMEM;
> +	}
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