Re: [Xen-devel] [PATCH v9 1/3] vt-d: fix the IOMMU flush issue

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.06.16 at 05:37, <quan.xu@xxxxxxxxx> wrote:
> @@ -546,17 +550,37 @@ static int __must_check iommu_flush_all(void)
>      struct acpi_drhd_unit *drhd;
>      struct iommu *iommu;
>      int flush_dev_iotlb;
> +    int rc = 0;
>  
>      flush_all_cache();
>      for_each_drhd_unit ( drhd )
>      {
> +        int context_rc, iotlb_rc;
> +
>          iommu = drhd->iommu;
> -        iommu_flush_context_global(iommu, 0);
> +        context_rc = iommu_flush_context_global(iommu, 0);
>          flush_dev_iotlb = find_ats_dev_drhd(iommu) ? 1 : 0;
> -        iommu_flush_iotlb_global(iommu, 0, flush_dev_iotlb);
> +        iotlb_rc = iommu_flush_iotlb_global(iommu, 0, flush_dev_iotlb);
> +
> +        /*
> +         * The current logic for returns:
> +         *   - positive  invoke iommu_flush_write_buffer to flush cache.
> +         *   - zero      on success.
> +         *   - negative  on failure. Continue to flush IOMMU IOTLB on a
> +         *               best effort basis.
> +         */
> +        if ( context_rc > 0 || iotlb_rc > 0 )
> +            iommu_flush_write_buffer(iommu);
> +        if ( context_rc >= 0 )

Wasn't this meant to be just "rc"? (I can't, btw, imagine Kevin's ack
to be rightfully retained with a change like this.)

Jan


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