On 2011-09-08 07:33, bharata....@gmail.com wrote:
> From: Bharata B Rao <bharata....@gmail.com>
>
> apic id returned to guest kernel in ebx for cpuid(function=1) depends on
> CPUX86State->cpuid_apic_id which gets populated after the cpuid information
> is cached in the host kernel. This results in broken CPU topology in guest.
>
> Fix this by setting cpuid_apic_id before cpuid information is passed to
> the host kernel. This is done by moving the setting of cpuid_apic_id
> to cpu_x86_init() where it will work for both KVM as well as TCG modes.
>
> Signed-off-by: Bharata B Rao <bharata....@gmail.com>
> ---
> This is the next post of the fix that addresses Jan's comment about
> bringing back (smp_cpus > 1) check.
>
> The previous version was posted here:
> http://lists.gnu.org/archive/html/qemu-devel/2011-09/msg00892.html
>
> I coudn't boot a 486 kernel successfully with qemu and hence not
> sure if and how this fix breaks i486. Any help from Jan or others
> who might have easy means to boot 486 would be good.
At least it preserves the current logic, just moves it up in the
initialization path.
>
> hw/pc.c | 1 -
> target-i386/helper.c | 5 +++++
> 2 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/hw/pc.c b/hw/pc.c
> index 5bc845a..f9cca4d 100644
> --- a/hw/pc.c
> +++ b/hw/pc.c
> @@ -933,7 +933,6 @@ static CPUState *pc_new_cpu(const char *cpu_model)
> exit(1);
> }
> if ((env->cpuid_features & CPUID_APIC) || smp_cpus > 1) {
> - env->cpuid_apic_id = env->cpu_index;
> env->apic_state = apic_init(env, env->cpuid_apic_id);
> }
> qemu_register_reset(pc_cpu_reset, env);
> diff --git a/target-i386/helper.c b/target-i386/helper.c
> index 5df40d4..139a193 100644
> --- a/target-i386/helper.c
> +++ b/target-i386/helper.c
> @@ -1256,6 +1256,11 @@ CPUX86State *cpu_x86_init(const char *cpu_model)
> cpu_x86_close(env);
> return NULL;
> }
> +
> + if ((env->cpuid_features & CPUID_APIC) || smp_cpus > 1) {
> + env->cpuid_apic_id = env->cpu_index;
> + }
> +
> mce_init(env);
>
> qemu_init_vcpu(env);
Tested-and-acked-by: Jan Kiszka <jan.kis...@siemens.com>
Just in time, we happen to hit this bug today too. It confused libvirt
in the guest quite a bit...
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
