Re: [PATCH 3/4] iommu/vt-d: Reject unsupported page request modes

[Lu Baolu <baolu.lu@linux.intel.com>]

On 2/19/21 5:31 AM, Jacob Pan wrote:
> When supervisor/privilige mode SVM is used, we bind init_mm.pgd with
> a supervisor PASID. There should not be any page fault for init_mm.
> Execution request with DMA read is also not supported.
> 
> This patch checks PRQ descriptor for both unsupported configurations,
> reject them both with invalid responses.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>

Fixes: 1c4f88b7f1f92 ("iommu/vt-d: Shared virtual address in scalable mode")
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu

> ---
>   drivers/iommu/intel/svm.c | 12 +++++++++++-
>   1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index 23a1e4f58c54..ff7ae7cc17d5 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -1113,7 +1113,17 @@ static irqreturn_t prq_event_thread(int irq, void *d)
>   			       ((unsigned long long *)req)[1]);
>   			goto no_pasid;
>   		}
> -
> +		/* We shall not receive page request for supervisor SVM */
> +		if (req->pm_req && (req->rd_req | req->wr_req)) {
> +			pr_err("Unexpected page request in Privilege Mode");
> +			/* No need to find the matching sdev as for bad_req */
> +			goto no_pasid;
> +		}
> +		/* DMA read with exec requeset is not supported. */
> +		if (req->exe_req && req->rd_req) {
> +			pr_err("Execution request not supported\n");
> +			goto no_pasid;
> +		}
>   		if (!svm || svm->pasid != req->pasid) {
>   			rcu_read_lock();
>   			svm = ioasid_find(NULL, req->pasid, NULL);
> 
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