linux-kernel - Re: [PATCH v11 05/10] iommu/vt-d: Add functions to load and save old re

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Date:	Tue, 12 May 2015 16:37:45 +0800
From:	Dave Young <dyoung@...hat.com>
To:	"Li, Zhen-Hua" <zhen-hual@...com>
Cc:	dwmw2@...radead.org, indou.takao@...fujitsu.com, bhe@...hat.com,
	joro@...tes.org, vgoyal@...hat.com,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, kexec@...ts.infradead.org,
	alex.williamson@...hat.com, ddutile@...hat.com,
	ishii.hironobu@...fujitsu.com, bhelgaas@...gle.com,
	doug.hatch@...com, jerry.hoemann@...com, tom.vaden@...com,
	li.zhang6@...com, lisa.mitchell@...com, billsumnerlinux@...il.com,
	rwright@...com
Subject: Re: [PATCH v11 05/10] iommu/vt-d: Add functions to load and save old
 re

Seems the subject was truncated? Maybe "re" means root entry? Then please fix it

On 05/11/15 at 05:52pm, Li, Zhen-Hua wrote:
> Add functions to load root entry table from old kernel, and to save updated
> root entry table.
> Add two member in struct intel_iommu, to store the RTA in old kernel, and
> the mapped virt address of it.

Please explain a bit what is "RTA" in patch log, it is unclear to most of people
who do not know iommu details.

> 
> We use the old RTA in dump kernel, and when the iommu->root_entry is used as
> a cache in kdump kernel, its phys address will not be save to RTA register,
> but when its data is changed, we will save the new data to old root entry table.
> 
> Li, Zhen-hua:
>     The functions and logics.
> 
> Takao Indoh:
>     Add __iommu_flush_cache.
> 
> Signed-off-by: Li, Zhen-Hua <zhen-hual@...com>
> Signed-off-by: Takao Indoh <indou.takao@...fujitsu.com>
> ---
>  drivers/iommu/intel-iommu.c | 54 ++++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/intel-iommu.h |  3 +++
>  2 files changed, 56 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 0b97c15..3a5d446 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -371,6 +371,10 @@ static struct context_entry *device_to_existing_context_entry(
>  				struct intel_iommu *iommu,
>  				u8 bus, u8 devfn);
>  
> +static void __iommu_load_old_root_entry(struct intel_iommu *iommu);
> +
> +static void __iommu_update_old_root_entry(struct intel_iommu *iommu, int index);
> +
>  /*
>   * A structure used to store the address allocated by ioremap();
>   * The we need to call iounmap() to free them out of spin_lock_irqsave/unlock;
> @@ -382,7 +386,6 @@ struct iommu_remapped_entry {
>  static LIST_HEAD(__iommu_remapped_mem);
>  static DEFINE_MUTEX(__iommu_mem_list_lock);
>  
> -
>  /*
>   * This domain is a statically identity mapping domain.
>   *	1. This domain creats a static 1:1 mapping to all usable memory.
> @@ -4935,3 +4938,52 @@ int __iommu_free_mapped_mem(void)
>  	return 0;
>  }
>  
> +/*
> + * Load the old root entry table to new root entry table.
> + */
> +static void __iommu_load_old_root_entry(struct intel_iommu *iommu)
> +{
> +	if ((!iommu)
> +		|| (!iommu->root_entry)
> +		|| (!iommu->root_entry_old_virt)
> +		|| (!iommu->root_entry_old_phys))
> +		return;
> +	memcpy(iommu->root_entry, iommu->root_entry_old_virt, PAGE_SIZE);
> +
> +	__iommu_flush_cache(iommu, iommu->root_entry, PAGE_SIZE);
> +}
> +
> +/*
> + * When the data in new root entry table is changed, this function
> + * must be called to save the updated data to old root entry table.
> + */
> +static void __iommu_update_old_root_entry(struct intel_iommu *iommu, int index)
> +{
> +	u8 start;
> +	unsigned long size;
> +	void __iomem *to;
> +	void *from;
> +
> +	if ((!iommu)
> +		|| (!iommu->root_entry)
> +		|| (!iommu->root_entry_old_virt)
> +		|| (!iommu->root_entry_old_phys))
> +		return;
> +
> +	if (index < -1 || index >= ROOT_ENTRY_NR)
> +		return;
> +
> +	if (index == -1) {
> +		start = 0;
> +		size = ROOT_ENTRY_NR * sizeof(struct root_entry);
> +	} else {
> +		start = index * sizeof(struct root_entry);
> +		size = sizeof(struct root_entry);
> +	}
> +	to = iommu->root_entry_old_virt;
> +	from = iommu->root_entry;
> +	memcpy(to + start, from + start, size);
> +
> +	__iommu_flush_cache(iommu, to + start, size);
> +}
> +
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index ced1fac..e7cac12 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -340,6 +340,9 @@ struct intel_iommu {
>  	spinlock_t	lock; /* protect context, domain ids */
>  	struct root_entry *root_entry; /* virtual address */
>  
> +	void __iomem	*root_entry_old_virt; /* mapped from old root entry */
> +	unsigned long	root_entry_old_phys; /* root entry in old kernel */
> +
>  	struct iommu_flush flush;
>  #endif
>  	struct q_inval  *qi;            /* Queued invalidation info */
> -- 
> 2.0.0-rc0
> 
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