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SubjectRe: [PATCH v11 02/10] iommu/vt-d: Items required for kdump
On 05/11/15 at 05:52pm, Li, Zhen-Hua wrote:
> Add context entry functions needed for kdump.
>
> Bill Sumner:
> Original version;
>
> Li, Zhenhua:
> Changed the name of new functions, make them consistent with current
> context get/set functions.
> Remove the structure dve which is not used in new version.
>
> Signed-off-by: Bill Sumner <billsumnerlinux@gmail.com>
> Signed-off-by: Li, Zhen-Hua <zhen-hual@hp.com>
> ---
> drivers/iommu/intel-iommu.c | 72 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 72 insertions(+)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index cb9d6cc..1e7ceb5 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -190,6 +190,31 @@ struct root_entry {
> };
> #define ROOT_ENTRY_NR (VTD_PAGE_SIZE/sizeof(struct root_entry))
>
> +static inline bool root_present(struct root_entry *root)
> +{
> + return (root->lo & 1);
> +}
> +
> +static inline void set_root_value(struct root_entry *root, unsigned long value)
> +{
> + root->lo &= ~VTD_PAGE_MASK;
> + root->lo |= value & VTD_PAGE_MASK;
> +}
> +
> +static inline struct context_entry *
> +get_context_addr_from_root(struct root_entry *root)
> +{
> + return (struct context_entry *)
> + (root_present(root)?phys_to_virt(
> + root->lo & VTD_PAGE_MASK) :
> + NULL);
> +}
> +
> +static inline unsigned long
> +get_context_phys_from_root(struct root_entry *root)
> +{
> + return root_present(root) ? (root->lo & VTD_PAGE_MASK) : 0;
> +}
>
> /*
> * low 64 bits:
> @@ -211,6 +236,32 @@ static inline bool context_present(struct context_entry *context)
> {
> return (context->lo & 1);
> }
> +
> +static inline int context_fault_enable(struct context_entry *c)
> +{
> + return((c->lo >> 1) & 0x1);
> +}
> +
> +static inline int context_translation_type(struct context_entry *c)
> +{
> + return((c->lo >> 2) & 0x3);
> +}
> +
> +static inline u64 context_address_root(struct context_entry *c)
> +{
> + return((c->lo >> VTD_PAGE_SHIFT));
> +}
> +
> +static inline int context_address_width(struct context_entry *c)
> +{
> + return((c->hi >> 0) & 0x7);
> +}
> +
> +static inline int context_domain_id(struct context_entry *c)
> +{
> + return((c->hi >> 8) & 0xffff);
> +}
> +
> static inline void context_set_present(struct context_entry *context)
> {
> context->lo |= 1;
> @@ -296,6 +347,27 @@ static inline int first_pte_in_page(struct dma_pte *pte)
> return !((unsigned long)pte & ~VTD_PAGE_MASK);
> }
>
> +
> +/*
> + * Fix Crashdump failure caused by leftover DMA through a hardware IOMMU
> + *
> + * Fixes the crashdump kernel to deal with an active iommu and legacy
> + * DMA from the (old) panicked kernel in a manner similar to how legacy
> + * DMA is handled when no hardware iommu was in use by the old kernel --
> + * allow the legacy DMA to continue into its current buffers.
> + *
> + * In the crashdump kernel, this code:
> + * 1. skips disabling the IOMMU's translating.
> + * 2. Do not re-enable IOMMU's translating.
> + * 3. In kdump kernel, use the old root entry table.
> + * 4. Allocate pages for new context entry, copy data from old context entries
> + * in the old kernel to the new ones.
> + *
> + * In other kinds of kernel, for example, a kernel started by kexec,
> + * do the same thing as crashdump kernel.
> + */
> +
> +

Above comments should come along with the code changes instead of putting it
in this patch.

BTW, there's one more blank line at the end..

> /*
> * This domain is a statically identity mapping domain.
> * 1. This domain creats a static 1:1 mapping to all usable memory.
> --
> 2.0.0-rc0
>


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