linux-kernel - Re: [PATCH v4 02/17] remoteproc: add rproc_va_to

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Date:   Tue, 23 Oct 2018 11:50:38 -0500
From:   Suman Anna <s-anna@...com>
To:     Loic Pallardy <loic.pallardy@...com>, <bjorn.andersson@...aro.org>,
        <ohad@...ery.com>
CC:     <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <arnaud.pouliquen@...com>, <benjamin.gaignard@...aro.org>
Subject: Re: [PATCH v4 02/17] remoteproc: add rproc_va_to_pa function

Hi Loic, Bjorn,

On 7/27/18 8:14 AM, Loic Pallardy wrote:
> This new function translates CPU virtual address in
> CPU physical one according to virtual address location.
> 
> Signed-off-by: Loic Pallardy <loic.pallardy@...com>
> Acked-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>  drivers/remoteproc/remoteproc_core.c | 18 +++++++++++++++++-
>  1 file changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index 437fabf..8e5fe1e 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -140,6 +140,22 @@ static void rproc_disable_iommu(struct rproc *rproc)
>  	iommu_domain_free(domain);
>  }
>  
> +static phys_addr_t rproc_va_to_pa(void *cpu_addr)
> +{
> +	/*
> +	 * Return physical address according to virtual address location
> +	 * - in vmalloc: if region ioremapped or defined as dma_alloc_coherent
> +	 * - in kernel: if region allocated in generic dma memory pool
> +	 */
> +	if (is_vmalloc_addr(cpu_addr)) {
> +		return page_to_phys(vmalloc_to_page(cpu_addr)) +
> +				    offset_in_page(cpu_addr);
> +	}
> +
> +	WARN_ON(!virt_addr_valid(cpu_addr));
> +	return virt_to_phys(cpu_addr);
> +}
> +
>  /**
>   * rproc_da_to_va() - lookup the kernel virtual address for a remoteproc address
>   * @rproc: handle of a remote processor
> @@ -711,7 +727,7 @@ static int rproc_handle_carveout(struct rproc *rproc,
>  	 * In this case, the device address and the physical address
>  	 * are the same.
>  	 */
> -	rsc->pa = dma;
> +	rsc->pa = (u32)rproc_va_to_pa(va);

While I agree with the direction here, we ought to add a check here
warning users if some address bits are getting lost as a result of the
typecast. Granted the issue may have been present previously with
dma_addr_t as well, but most platforms were using 32-bit dma addresses,
so this was kinda masked. There are ARMv7 platforms with LPAE enabled
allowing physical addresses > 32-bits.

In anycase, we definitely have a need for a v2 for the fw_rsc_carveout
structure to deal with 64-bit addresses.

regards
Suman

>  
>  	carveout->va = va;
>  	carveout->len = rsc->len;
>