linux-kernel - Re: [PATCH v5 8/8] iommu/amd: Update domain into to dte entry during device driver init

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Date:   Tue, 20 Sep 2016 14:53:30 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Baoquan He <bhe@...hat.com>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        kexec@...ts.infradead.org, dyoung@...hat.com, xlpang@...hat.com,
        Vincent.Wan@....com
Subject: Re: [PATCH v5 8/8] iommu/amd: Update domain into to dte entry during
 device driver init

On Thu, Sep 15, 2016 at 11:03:26PM +0800, Baoquan He wrote:
> All devices are supposed to reset themselves at device driver initialization
> stage. At this time if in kdump kernel those on-flight DMA will be stopped
> because of device reset. It's best time to update the protection domain info,
> especially pte_root, to dte entry which the device relates to.
> 
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  drivers/iommu/amd_iommu.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index 6c37300..00b64ee 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -2310,6 +2310,10 @@ static dma_addr_t __map_single(struct device *dev,
>  	unsigned int pages;
>  	int prot = 0;
>  	int i;
> +	struct iommu_dev_data *dev_data = get_dev_data(dev);
> +	struct protection_domain *domain = get_domain(dev);
> +	u16 alias = amd_iommu_alias_table[dev_data->devid];
> +	struct amd_iommu *iommu = amd_iommu_rlookup_table[dev_data->devid];
>  
>  	pages = iommu_num_pages(paddr, size, PAGE_SIZE);
>  	paddr &= PAGE_MASK;
> @@ -2319,6 +2323,13 @@ static dma_addr_t __map_single(struct device *dev,
>  		goto out;
>  
>  	prot = dir2prot(direction);
> +	if (translation_pre_enabled(iommu) && !dev_data->domain_updated) {
> +               dev_data->domain_updated = true;
> +               set_dte_entry(dev_data->devid, domain, dev_data->ats.enabled);
> +               if (alias != dev_data->devid)
> +                       set_dte_entry(alias, domain, dev_data->ats.enabled);
> +               device_flush_dte(dev_data);
> +       }

Hmm, have you tried hooking this into the set_dma_mask call-back? Every
driver should call it for its device, so that should be a better
indicator to now map a new domain.


	Joerg