On 7/16/25 6:13 PM, Zhao Liu wrote:
> On Wed, Jul 16, 2025 at 05:22:46PM +0200, Paolo Bonzini wrote:
>> Date: Wed, 16 Jul 2025 17:22:46 +0200
>> From: Paolo Bonzini <pbonz...@redhat.com>
>> Subject: Re: boot failure on top of current git
>>
>> On 7/16/25 16:44, Paolo Abeni wrote:
>>> Hi,
>>>
>>> I'm observing boot failure for a rhel-9.7 VM. I'm using qemu git tree at
>>> commit c079d3a31e.
>>
>> No and I cannot reproduce it.
>>
>> What host is it (processor) and kernel version?
>>
>> Paolo
>
> It sounds like x86_ext_save_areas[] wasn't initialized correctly.
>
> I just checked the related logic, in the previous QEMU, for
> x86_cpu_post_initfn(),
> it initialized x86_ext_save_areas[] first, then called
> accel_cpu_instance_init(),
> so that KVM's xsave assertion didn't complain.
>
> But now, when we move accel_cpu_instance_init() to x86_cpu_initfn(), KVM
> checks x86_ext_save_areas[] before x86_ext_save_areas[] initialization.
>
> I understand, we should initialize x86_ext_save_areas[] in
> x86_cpu_initfn() as well. Maybe we need something like this:
>
> ---
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index da7d8dca633e..c8fccabeee71 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -9619,6 +9619,16 @@ static void
> x86_cpu_register_feature_bit_props(X86CPUClass *xcc,
> }
>
> static void x86_cpu_post_initfn(Object *obj)
> +{
> +#ifndef CONFIG_USER_ONLY
> + if (current_machine && current_machine->cgs) {
> + x86_confidential_guest_cpu_instance_init(
> + X86_CONFIDENTIAL_GUEST(current_machine->cgs), (CPU(obj)));
> + }
> +#endif
> +}
> +
> +static void x86_cpu_init_xsave(void)
> {
> static bool first = true;
> uint64_t supported_xcr0;
> @@ -9639,13 +9649,6 @@ static void x86_cpu_post_initfn(Object *obj)
> }
> }
> }
> -
> -#ifndef CONFIG_USER_ONLY
> - if (current_machine && current_machine->cgs) {
> - x86_confidential_guest_cpu_instance_init(
> - X86_CONFIDENTIAL_GUEST(current_machine->cgs), (CPU(obj)));
> - }
> -#endif
> }
>
> static void x86_cpu_init_default_topo(X86CPU *cpu)
> @@ -9715,6 +9718,7 @@ static void x86_cpu_initfn(Object *obj)
> x86_cpu_load_model(cpu, xcc->model);
> }
>
> + x86_cpu_init_xsave();
> accel_cpu_instance_init(CPU(obj));
> }
FWIW, I can boot successfully my VM on top of c079d3a31e plus the above
patch.
If the above turns into a formal patch feel free to add:
Tested-by: Paolo Abeni <pab...@redhat.com>
Thanks,
Paolo
