| Message ID | CAGZKiBpXSCYtK2q-KWd+bCP6xFURWu6xR5tT_eimc3+Pd-71YA@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Aug 17, 2011 at 10:55 AM, Bharata B Rao <bharata.rao@gmail.com> 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. Going by the lack of response I assume not many people are using - smp option with sockets, cores and threads specified explicitly ? Or is it that I hit a corner case and not using the -smp option correctly enough ? Regards, Bharata.
> 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. > > 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 Please post a patch against qemu.git master branch. > > + if (env->cpuid_features & CPUID_APIC) > + env->cpuid_apic_id = env->cpu_index; > + qemu coding style requires braces even around single statements in if () blocks.
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.rao@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
On Thu, Aug 25, 2011 at 3:31 PM, Avi Kivity <avi@redhat.com> 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. >> > >> 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 > > Please post a patch against qemu.git master branch. Sure I will rebase. The previous version was just a quick and hackish change, I just wanted pass by the list. > >> >> + if (env->cpuid_features & CPUID_APIC) >> + env->cpuid_apic_id = env->cpu_index; >> + > > qemu coding style requires braces even around single statements in if () blocks. Sure. Thanks, Bharata.
On Thu, Aug 25, 2011 at 4:17 PM, Jan Kiszka <jan.kiszka@siemens.com> wrote: > On 2011-08-17 07:25, Bharata B Rao wrote: >> 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. Thanks for the review. The patch was just a quick fix. Let me work on a proper fix that addresses your comments. Regards, Bharata.
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; + #ifdef CONFIG_KVM_PARA /* Paravirtualization CPUIDs */ memcpy(signature, "KVMKVMKVM\0\0\0", 12);
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.rao@gmail.com> --- hw/pc.c | 4 +--- target-i386/kvm.c | 3 +++ 2 files changed, 4 insertions(+), 3 deletions(-) ************************** This is how various fields look like before and after this change with qemu command line option of "-smp ,sockets=1,cores=4,threads=2" Before ------ root@sqzy:~# grep "core id" /proc/cpuinfo core id : 0 core id : 0 core id : 0 core id : 0 core id : 0 core id : 0 core id : 0 core id : 0 After ----- root@sqzy:~# grep "core id" /proc/cpuinfo core id : 0 core id : 0 core id : 1 core id : 1 core id : 2 core id : 2 core id : 3 core id : 3 Before ------ root@sqzy:~# grep "cpu cores" /proc/cpuinfo cpu cores : 1 cpu cores : 1 cpu cores : 1 cpu cores : 1 cpu cores : 1 cpu cores : 1 cpu cores : 1 cpu cores : 1 After ----- root@sqzy:~# grep "cpu cores" /proc/cpuinfo cpu cores : 4 cpu cores : 4 cpu cores : 4 cpu cores : 4 cpu cores : 4 cpu cores : 4 cpu cores : 4 cpu cores : 4 Before ------ root@sqzy:~# grep apicid /proc/cpuinfo apicid : 0 initial apicid : 0 apicid : 0 initial apicid : 0 apicid : 0 initial apicid : 0 apicid : 0 initial apicid : 0 apicid : 0 initial apicid : 0 apicid : 0 initial apicid : 0 apicid : 0 initial apicid : 0 apicid : 0 initial apicid : 0 After ----- root@sqzy:~# grep apicid /proc/cpuinfo apicid : 0 initial apicid : 0 apicid : 1 initial apicid : 1 apicid : 2 initial apicid : 2 apicid : 3 initial apicid : 3 apicid : 4 initial apicid : 4 apicid : 5 initial apicid : 5 apicid : 6 initial apicid : 6 apicid : 7 initial apicid : 7 Before ------ root@sqzy:/sys/devices/system/cpu# cat cpu*/topology/core_siblings_list 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7 root@sqzy:/sys/devices/system/cpu# cat cpu*/topology/thread_siblings_list 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7 After ----- root@sqzy:/sys/devices/system/cpu# cat cpu*/topology/core_siblings_list 0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7 root@sqzy:/sys/devices/system/cpu# cat cpu*/topology/thread_siblings_list 0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7 Regards, Bharata. -- http://bharata.sulekha.com/blog/posts.htm, http://raobharata.wordpress.com/