Re: [PATCH v5 5/6] dmaengine: pl330: Make sure microcode is privileged

From: Vinod Koul
Date: Mon Aug 08 2016 - 01:42:31 EST


On Wed, Jul 27, 2016 at 04:42:07PM -0700, Mitchel Humpherys wrote:
> The PL330 performs privileged instruction fetches. This can result in
> SMMU permission faults on SMMUs that implement the ARMv8 VMSA, which

Lot of acronyms with no explanation whatsoever

> specifies that mappings that are writeable at one execution level shall
> not be executable at any higher-privileged level. Fix this by using the
> DMA_ATTR_PRIVILEGED attribute, which will ensure that the microcode
> IOMMU mapping is only accessible to the privileged level.

And I get satndalone patch with no context for the series!

>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Vinod Koul <vinod.koul@xxxxxxxxx>
> Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
> Tested-by: Robin Murphy <robin.murphy@xxxxxxx>
> Signed-off-by: Mitchel Humpherys <mitchelh@xxxxxxxxxxxxxx>
> ---
>
> Notes:
> v3..v4
>
> - Reworked against the new dma attrs format.
>
> drivers/dma/pl330.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
> index 4fc3ffbd5ca0..8cd624fc3760 100644
> --- a/drivers/dma/pl330.c
> +++ b/drivers/dma/pl330.c
> @@ -1854,14 +1854,16 @@ static int dmac_alloc_resources(struct pl330_dmac *pl330)
> {
> int chans = pl330->pcfg.num_chan;
> int ret;
> + unsigned long dma_attrs = DMA_ATTR_PRIVILEGED;
>
> /*
> * Alloc MicroCode buffer for 'chans' Channel threads.
> * A channel's buffer offset is (Channel_Id * MCODE_BUFF_PERCHAN)
> */
> - pl330->mcode_cpu = dma_alloc_coherent(pl330->ddma.dev,
> + pl330->mcode_cpu = dma_alloc_attrs(pl330->ddma.dev,
> chans * pl330->mcbufsz,
> - &pl330->mcode_bus, GFP_KERNEL);
> + &pl330->mcode_bus, GFP_KERNEL,
> + dma_attrs);
> if (!pl330->mcode_cpu) {
> dev_err(pl330->ddma.dev, "%s:%d Can't allocate memory!\n",
> __func__, __LINE__);
> --
> Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>

--
~Vinod