On 2011-08-17 07:25, Bharata B Rao wrote:
> Hi,
>
> I see that x86 CPU topology inside VM is not showing up as specified.
> With some debugging, I found out that the root cause for this: qemu is
> not enumerating the apic ids correctly for vcpus. I made the below
> hackish change to get it working. Has anybody else seen this problem
> ? This patch is on qemu-kvm-0.14.1. Using 2.6.39 for guest.
>
> ***************************
> Fix apic id enumeration
>
> 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.
>
> Fix this by setting cpuid_apic_id before cpuid information is passed to
> the host kernel.
>
> Signed-off-by: Bharata B Rao <bharata....@gmail.com>
> ---
> hw/pc.c | 4 +---
> target-i386/kvm.c | 3 +++
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> Index: qemu-kvm-0.14.1/hw/pc.c
> ===================================================================
> --- qemu-kvm-0.14.1.orig/hw/pc.c
> +++ qemu-kvm-0.14.1/hw/pc.c
> @@ -930,10 +930,8 @@ CPUState *pc_new_cpu(const char *cpu_mod
> fprintf(stderr, "Unable to find x86 CPU definition\n");
> exit(1);
> }
> - if ((env->cpuid_features & CPUID_APIC) || smp_cpus > 1) {
> - env->cpuid_apic_id = env->cpu_index;
> + if ((env->cpuid_features & CPUID_APIC) || smp_cpus > 1)
> env->apic_state = apic_init(env, env->cpuid_apic_id);
> - }
> qemu_register_reset(pc_cpu_reset, env);
> pc_cpu_reset(env);
> return env;
> Index: qemu-kvm-0.14.1/target-i386/kvm.c
> ===================================================================
> --- qemu-kvm-0.14.1.orig/target-i386/kvm.c
> +++ qemu-kvm-0.14.1/target-i386/kvm.c
> @@ -340,6 +340,9 @@ int kvm_arch_init_vcpu(CPUState *env)
>
> cpuid_i = 0;
>
> + if (env->cpuid_features & CPUID_APIC)
> + env->cpuid_apic_id = env->cpu_index;
> +
Moving it only here will break TCG mode. Make sure to test both. I guess
it's best to move cpuid_apic_id initialization into cpu_x86_init. And
you need to take care of the external APIC case (i486) as well.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
