qemu aarch64 gicv3 memory-mapped registers can't be modified - qemu

Question

According to the info in generated dtb, the memory-mapped registers of gicv3-distributor have a base addr, which is 0x0800_0000.
And I have checked the validity by reading gicd_typer, which means the base addr is right.
But when I want to configure the gicv3-distributor (like changing GICD_ICACTIVER<n>), the value is not changed, keeping the default value. The same thing happens on any register of GICD in my machine.
I change them with assembly code as soon as the machine starts, not enable MMU.
ldr x8, =0x8000380
ldr x9, =0xffffffff
str x9, [x8]
dsb sy
ldr x0, [x8]
(gdb) i r x0
x0 0x0 0
Even I write to this memory by gdb set command, the value is also unchangeable.
The addr of GICD_ICACTIVER<n> should be 0x0800_0380(offset=0x380), which should be readable and writable, isn't it?
The UART(pl011)-related address(0x0900_0000) can be written normally.
Host machine: Ubuntu 18.04
qemu version: 7.1.50 (v7.1.0-256-g79dfa177)
Target OS: bare-metal
qemu command:
./qemu-system-aarch64 -machine virt,gic-version=3,secure=on,virtualization=on -cpu cortex-a76 -m 1G

Answer 1

The GICD_ICACTIVER register bits are write-1-to-clear, so if you write all-1s to the register then you should expect it to read back as all-0s.
More generally, not all hardware device registers will read back the same value that you write to them -- it depends entirely on the device.