Re: [RFC PATCH 1/4] hw: encode accessing CPU index in MemTxAttrs

[Richard Henderson]

On 9/14/22 17:09, Alex Bennée wrote:
> @@ -1340,8 +1340,13 @@ static uint64_t io_readx(CPUArchState *env, 
> CPUIOTLBEntry *iotlbentry,
>       uint64_t val;
>       bool locked = false;
>       MemTxResult r;
> +    MemTxAttrs attrs = iotlbentry->attrs;
>   
> -    section = iotlb_to_section(cpu, iotlbentry->addr, iotlbentry->attrs);
> +    /* encode the accessing CPU */
> +    attrs.requester_cpu = 1;
> +    attrs.requester_id = cpu->cpu_index;
> +
> +    section = iotlb_to_section(cpu, iotlbentry->addr, attrs);
>       mr = section->mr;
>       mr_offset = (iotlbentry->addr & TARGET_PAGE_MASK) + addr;
>       cpu->mem_io_pc = retaddr;

At first I was going to suggest that this be done in tlb_set_page_with_attrs, so that it 
could be done once and not duplicate code across read/write.

But then I got to thinking how this ought to interact with MEMTXATTRS_UNSPECIFIED, and now 
I think that we simply have to leave this to the cpu's tlb_fill routine, where it fills in 
(or doesn't) all of the other transaction attributes.


r~