Re: [PATCH v7 01/15] swiotlb: Refactor swiotlb init functions

[Florian Fainelli <f.fainelli@xxxxxxxxx>]

On 5/17/2021 11:42 PM, Claire Chang wrote:
> Add a new function, swiotlb_init_io_tlb_mem, for the io_tlb_mem struct
> initialization to make the code reusable.
> 
> Note that we now also call set_memory_decrypted in swiotlb_init_with_tbl.
> 
> Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
> ---
>  kernel/dma/swiotlb.c | 51 ++++++++++++++++++++++----------------------
>  1 file changed, 25 insertions(+), 26 deletions(-)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 8ca7d505d61c..d3232fc19385 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -168,9 +168,30 @@ void __init swiotlb_update_mem_attributes(void)
>       memset(vaddr, 0, bytes);
>  }
>  
> -int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int 
> verbose)
> +static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t 
> start,
> +                                 unsigned long nslabs, bool late_alloc)
>  {
> +     void *vaddr = phys_to_virt(start);
>       unsigned long bytes = nslabs << IO_TLB_SHIFT, i;
> +
> +     mem->nslabs = nslabs;
> +     mem->start = start;
> +     mem->end = mem->start + bytes;
> +     mem->index = 0;
> +     mem->late_alloc = late_alloc;
> +     spin_lock_init(&mem->lock);
> +     for (i = 0; i < mem->nslabs; i++) {
> +             mem->slots[i].list = IO_TLB_SEGSIZE - io_tlb_offset(i);
> +             mem->slots[i].orig_addr = INVALID_PHYS_ADDR;
> +             mem->slots[i].alloc_size = 0;
> +     }
> +
> +     set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
> +     memset(vaddr, 0, bytes);

You are doing an unconditional set_memory_decrypted() followed by a
memset here, and then:

> +}
> +
> +int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int 
> verbose)
> +{
>       struct io_tlb_mem *mem;
>       size_t alloc_size;
>  
> @@ -186,16 +207,8 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned 
> long nslabs, int verbose)
>       if (!mem)
>               panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
>                     __func__, alloc_size, PAGE_SIZE);
> -     mem->nslabs = nslabs;
> -     mem->start = __pa(tlb);
> -     mem->end = mem->start + bytes;
> -     mem->index = 0;
> -     spin_lock_init(&mem->lock);
> -     for (i = 0; i < mem->nslabs; i++) {
> -             mem->slots[i].list = IO_TLB_SEGSIZE - io_tlb_offset(i);
> -             mem->slots[i].orig_addr = INVALID_PHYS_ADDR;
> -             mem->slots[i].alloc_size = 0;
> -     }
> +
> +     swiotlb_init_io_tlb_mem(mem, __pa(tlb), nslabs, false);

You convert this call site with swiotlb_init_io_tlb_mem() which did not
do the set_memory_decrypted()+memset(). Is this okay or should
swiotlb_init_io_tlb_mem() add an additional argument to do this
conditionally?
-- 
Florian