linux-kernel - Re: [PATCH v5 1/4] firmware: scm: Add new SCM call API for switching memory ownership

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Date:   Fri, 2 Jun 2017 11:22:42 -0700
From:   Stephen Boyd <sboyd@...eaurora.org>
To:     Avaneesh Kumar Dwivedi <akdwived@...eaurora.org>
Cc:     bjorn.andersson@...aro.org, agross@...eaurora.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-remoteproc@...r.kernel.org
Subject: Re: [PATCH v5 1/4] firmware: scm: Add new SCM call API for switching
 memory ownership

On 06/02, Avaneesh Kumar Dwivedi wrote:
> Two different processors on a SOC need to switch memory ownership
> during load/unload. To enable this, level second memory map table

second level page tables instead of level second memory map table

> need to be updated, which is done by secure layer.
> This patch add the interface for making secure monitor call for

s/add/adds/

> memory ownership switching request.
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index bb16510..9da3c6d 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -292,6 +304,86 @@ int qcom_scm_pas_shutdown(u32 peripheral)
>  }
>  EXPORT_SYMBOL(qcom_scm_pas_shutdown);
>  
> +/**
> + * qcom_scm_assign_mem() - Make a secure call to reassign memory ownership
> + *
> + * @mem_addr: mem region whose ownership need to be reassigned
> + * @mem_sz:   size of the region.
> + * @srcvm:    vmid for current set of owners, each set bit in
> + *            flag indicate a unique owner
> + * @newvm:    array having new owners and corrsponding permission
> + *            flags
> + * @dest_cnt: number of owners in next set.
> + * Return next set of owners on success.
> + */
> +int qcom_scm_assign_mem(phys_addr_t mem_addr, size_t mem_sz, int srcvm,
> +			struct qcom_scm_vmperm *newvm, int dest_cnt)
> +{
> +	unsigned long dma_attrs = DMA_ATTR_FORCE_CONTIGUOUS;
> +	struct qcom_scm_current_perm_info *destvm;
> +	struct qcom_scm_mem_map_info *mem;
> +	phys_addr_t memory_phys;
> +	phys_addr_t dest_phys;
> +	phys_addr_t src_phys;
> +	size_t mem_all_sz;
> +	size_t memory_sz;
> +	size_t dest_sz;
> +	size_t src_sz;
> +	int next_vm;
> +	__le32 *src;
> +	void *ptr;
> +	int ret;
> +	int i;

Yay reverse christmas tre.

> +
> +	src_sz = hweight_long(srcvm)*sizeof(*src);

Please add space around that '*':

	src_sz = hweight_long(srcvm) * sizeof(*src);

> +	memory_sz = sizeof(*mem);
> +	dest_sz = dest_cnt*sizeof(*destvm);
> +	mem_all_sz = src_sz + memory_sz + dest_sz;
> +
> +	ptr = dma_alloc_attrs(__scm->dev, ALIGN(mem_all_sz, SZ_64),
> +		&src_phys, GFP_KERNEL, dma_attrs);
> +	if (!ptr) {
> +		pr_err("mem alloc failed\n");

We don't want memory allocation failure prints. Please remove.

> +		return -ENOMEM;
> +	}

Newline here!

> +	/* Fill source vmid detail */
> +	src = (__le32 *)(ptr);

Drop useless parenthesis around ptr please.

> +	ret = hweight_long(srcvm);

len = hweight_long(...)?

> +	for (i = 0; i < ret; i++) {

i to ret is really weird looking!

> +		src[i] = cpu_to_le32(ffs(srcvm) - 1);
> +		srcvm ^= 1 << (ffs(srcvm) - 1);
> +	}

What if the loop was written like:

	for_each_set_bit(i, &srcvm, sizeof(srcvm))
		src[i] = cpu_to_le32(i);

I guess srvcm would have to be a long then.

> +
> +	/* Fill details of mem buff to map */
> +	mem = (struct qcom_scm_mem_map_info *)(ptr + ALIGN(src_sz, SZ_64));

Useless cast from void *.

> +	memory_phys = src_phys + ALIGN(src_sz, SZ_64);
> +	mem[0].mem_addr = cpu_to_le64(mem_addr);
> +	mem[0].mem_size = cpu_to_le64(mem_sz);
> +
> +	next_vm = 0;
> +	/* Fill details of next vmid detail */
> +	destvm = (struct qcom_scm_current_perm_info *)
> +			(ptr + ALIGN(memory_sz, SZ_64) + ALIGN(src_sz, SZ_64));

Useless cast from void.

> +	dest_phys = memory_phys + ALIGN(memory_sz, SZ_64);
> +	for (i = 0; i < dest_cnt; i++) {
> +		destvm[i].vmid = cpu_to_le32(newvm[i].vmid);
> +		destvm[i].perm = cpu_to_le32(newvm[i].perm);
> +		destvm[i].ctx = 0;
> +		destvm[i].ctx_size = 0;
> +		next_vm |= BIT(newvm[i].vmid);
> +	}

Newline please!

> +	ret = __qcom_scm_assign_mem(__scm->dev, memory_phys,
> +		memory_sz, src_phys, src_sz, dest_phys, dest_sz);
> +	dma_free_attrs(__scm->dev, ALIGN(mem_all_sz, SZ_64),
> +		ptr, src_phys, dma_attrs);
> +	if (ret == 0)
> +		return next_vm;
> +	else if (ret > 0)
> +		return -ret;

When is ret > 0?

> +	return ret;
> +}
> +EXPORT_SYMBOL(qcom_scm_assign_mem);
> +
>  static int qcom_scm_pas_reset_assert(struct reset_controller_dev *rcdev,
>  				     unsigned long idx)
>  {
-- 
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