Hello,
I would be happy if you could give me some comments.
ping.
On Thu, Feb 1, 2024 at 5:14 PM Tomoyuki HIROSE
<tomoyuki.hir...@igel.co.jp> wrote:
>
> The previous code ignored 'impl.unaligned' and handled unaligned accesses
> as is. But this implementation cannot emulate specific registers of some
> devices that allow unaligned access such as xHCI Host Controller Capability
> Registers.
> This commit checks 'impl.unaligned' and if it is false, QEMU emulates
> unaligned access with multiple aligned access.
>
> Signed-off-by: Tomoyuki HIROSE <tomoyuki.hir...@igel.co.jp>
> ---
> system/memory.c | 38 +++++++++++++++++++++++++-------------
> 1 file changed, 25 insertions(+), 13 deletions(-)
>
> diff --git a/system/memory.c b/system/memory.c
> index a229a79988..a7ca0c9f54 100644
> --- a/system/memory.c
> +++ b/system/memory.c
> @@ -535,10 +535,17 @@ static MemTxResult access_with_adjusted_size(hwaddr
> addr,
> MemTxAttrs attrs)
> {
> uint64_t access_mask;
> + unsigned access_mask_shift;
> + unsigned access_mask_start_offset;
> + unsigned access_mask_end_offset;
> unsigned access_size;
> - unsigned i;
> MemTxResult r = MEMTX_OK;
> bool reentrancy_guard_applied = false;
> + bool is_big_endian = memory_region_big_endian(mr);
> + signed start_diff;
> + signed current_offset;
> + signed access_shift;
> + hwaddr current_addr;
>
> if (!access_size_min) {
> access_size_min = 1;
> @@ -560,19 +567,24 @@ static MemTxResult access_with_adjusted_size(hwaddr
> addr,
> reentrancy_guard_applied = true;
> }
>
> - /* FIXME: support unaligned access? */
> access_size = MAX(MIN(size, access_size_max), access_size_min);
> - access_mask = MAKE_64BIT_MASK(0, access_size * 8);
> - if (memory_region_big_endian(mr)) {
> - for (i = 0; i < size; i += access_size) {
> - r |= access_fn(mr, addr + i, value, access_size,
> - (size - access_size - i) * 8, access_mask, attrs);
> - }
> - } else {
> - for (i = 0; i < size; i += access_size) {
> - r |= access_fn(mr, addr + i, value, access_size, i * 8,
> - access_mask, attrs);
> - }
> + start_diff = mr->ops->impl.unaligned ? 0 : addr & (access_size - 1);
> + current_addr = addr - start_diff;
> + for (current_offset = -start_diff; current_offset < (signed)size;
> + current_offset += access_size, current_addr += access_size) {
> + access_shift = is_big_endian
> + ? (signed)size - (signed)access_size -
> current_offset
> + : current_offset;
> + access_mask_shift = current_offset > 0 ? 0 : -current_offset;
> + access_mask_start_offset = current_offset > 0 ? current_offset : 0;
> + access_mask_end_offset = current_offset + access_size > size
> + ? size
> + : current_offset + access_size;
> + access_mask = MAKE_64BIT_MASK(access_mask_shift * 8,
> + (access_mask_end_offset - access_mask_start_offset) * 8);
> +
> + r |= access_fn(mr, current_addr, value, access_size, access_shift *
> 8,
> + access_mask, attrs);
> }
> if (mr->dev && reentrancy_guard_applied) {
> mr->dev->mem_reentrancy_guard.engaged_in_io = false;
> --
> 2.39.2
>
