On Thu, 16 Jan 2025 at 14:05, David Woodhouse <dw...@infradead.org> wrote:
>
> From: David Woodhouse <d...@amazon.co.uk>
>
> The vmclock device addresses the problem of live migration with
> precision clocks. The tolerances of a hardware counter (e.g. TSC) are
> typically around ±50PPM. A guest will use NTP/PTP/PPS to discipline that
> counter against an external source of 'real' time, and track the precise
> frequency of the counter as it changes with environmental conditions.
Hi; I see this has already gone into git, but:
> +static void vmclock_realize(DeviceState *dev, Error **errp)
> +{
> + VmclockState *vms = VMCLOCK(dev);
> +
> + /*
> + * Given that this function is executing, there is at least one VMCLOCK
> + * device. Check if there are several.
> + */
> + if (!find_vmclock_dev()) {
> + error_setg(errp, "at most one %s device is permitted", TYPE_VMCLOCK);
> + return;
> + }
> +
> + vms->physaddr = VMCLOCK_ADDR;
> +
> + e820_add_entry(vms->physaddr, VMCLOCK_SIZE, E820_RESERVED);
> +
> + memory_region_init_ram(&vms->clk_page, OBJECT(dev), "vmclock_page",
> + VMCLOCK_SIZE, &error_abort);
> + memory_region_set_enabled(&vms->clk_page, true);
> + vms->clk = memory_region_get_ram_ptr(&vms->clk_page);
> + memset(vms->clk, 0, VMCLOCK_SIZE);
> +
> + vms->clk->magic = cpu_to_le32(VMCLOCK_MAGIC);
> + vms->clk->size = cpu_to_le16(VMCLOCK_SIZE);
> + vms->clk->version = cpu_to_le16(1);
> +
> + /* These are all zero and thus default, but be explicit */
> + vms->clk->clock_status = VMCLOCK_STATUS_UNKNOWN;
> + vms->clk->counter_id = VMCLOCK_COUNTER_INVALID;
> +
> + qemu_register_reset(vmclock_handle_reset, vms);
No new calls to qemu_register_reset(), please. This is
a device, use the device reset API.
> +
> + vmclock_update_guest(vms);
> +}
Can you send a patch to fix this, please?
thanks
-- PMM
