Re: [Qemu-devel] [PATCH 27/28] target-i386: kvm_cpu_fill_host: use GET_SUPPORTED_CPUID

[Eduardo Habkost]

On Fri, Nov 02, 2012 at 04:34:00PM +0100, Andreas Färber wrote:
> Am 31.10.2012 10:40, schrieb Marcelo Tosatti:
> > From: Eduardo Habkost <address@hidden>
> > 
> > Change the kvm_cpu_fill_host() function to use
> > kvm_arch_get_supported_cpuid() instead of running the CPUID instruction
> > directly, when checking for supported CPUID features.
> > 
> > This should solve two problems at the same time:
> > 
> >  * "-cpu host" was not enabling features that don't need support on
> >    the host CPU (e.g. x2apic);
> >  * "check" and "enforce" options were not detecting problems when the
> >    host CPU did support a feature, but the KVM kernel code didn't
> >    support it.
> > 
> > Signed-off-by: Eduardo Habkost <address@hidden>
> > Signed-off-by: Marcelo Tosatti <address@hidden>
> > ---
> >  target-i386/cpu.c |   25 +++++++++++++++----------
> >  1 files changed, 15 insertions(+), 10 deletions(-)
> > 
> > diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> > index 390ed47..4c84e9f 100644
> > --- a/target-i386/cpu.c
> > +++ b/target-i386/cpu.c
> > @@ -773,13 +773,13 @@ static int cpu_x86_fill_model_id(char *str)
> >   */
> >  static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
> >  {
> > +    KVMState *s = kvm_state;
> 
> This broke the linux-user build:
> 
> target-i386/cpu.o: In function `kvm_cpu_fill_host':
> /home/andreas/QEMU/qemu-rcar/target-i386/cpu.c:783: undefined reference
> to `kvm_state'
> collect2: error: ld returned 1 exit status
> make[1]: *** [qemu-i386] Fehler 1
> make: *** [subdir-i386-linux-user] Fehler 2
> 
> Any idea how to fix?

This function should never be called without CONFIG_KVM, so we can
#ifdef out the whole function body. I will send a patch shortly.


> 
> Andreas
> 
> >      uint32_t eax = 0, ebx = 0, ecx = 0, edx = 0;
> >  
> >      assert(kvm_enabled());
> >  
> >      x86_cpu_def->name = "host";
> >      host_cpuid(0x0, 0, &eax, &ebx, &ecx, &edx);
> > -    x86_cpu_def->level = eax;
> >      x86_cpu_def->vendor1 = ebx;
> >      x86_cpu_def->vendor2 = edx;
> >      x86_cpu_def->vendor3 = ecx;
> > @@ -788,21 +788,24 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
> >      x86_cpu_def->family = ((eax >> 8) & 0x0F) + ((eax >> 20) & 0xFF);
> >      x86_cpu_def->model = ((eax >> 4) & 0x0F) | ((eax & 0xF0000) >> 12);
> >      x86_cpu_def->stepping = eax & 0x0F;
> > -    x86_cpu_def->ext_features = ecx;
> > -    x86_cpu_def->features = edx;
> > +
> > +    x86_cpu_def->level = kvm_arch_get_supported_cpuid(s, 0x0, 0, R_EAX);
> > +    x86_cpu_def->features = kvm_arch_get_supported_cpuid(s, 0x1, 0, R_EDX);
> > +    x86_cpu_def->ext_features = kvm_arch_get_supported_cpuid(s, 0x1, 0, 
> > R_ECX);
> >  
> >      if (x86_cpu_def->level >= 7) {
> > -        x86_cpu_def->cpuid_7_0_ebx_features = 
> > kvm_arch_get_supported_cpuid(kvm_state, 0x7, 0, R_EBX);
> > +        x86_cpu_def->cpuid_7_0_ebx_features =
> > +                    kvm_arch_get_supported_cpuid(s, 0x7, 0, R_EBX);
> >      } else {
> >          x86_cpu_def->cpuid_7_0_ebx_features = 0;
> >      }
> >  
> > -    host_cpuid(0x80000000, 0, &eax, &ebx, &ecx, &edx);
> > -    x86_cpu_def->xlevel = eax;
> > +    x86_cpu_def->xlevel = kvm_arch_get_supported_cpuid(s, 0x80000000, 0, 
> > R_EAX);
> > +    x86_cpu_def->ext2_features =
> > +                kvm_arch_get_supported_cpuid(s, 0x80000001, 0, R_EDX);
> > +    x86_cpu_def->ext3_features =
> > +                kvm_arch_get_supported_cpuid(s, 0x80000001, 0, R_ECX);
> >  
> > -    host_cpuid(0x80000001, 0, &eax, &ebx, &ecx, &edx);
> > -    x86_cpu_def->ext2_features = edx;
> > -    x86_cpu_def->ext3_features = ecx;
> >      cpu_x86_fill_model_id(x86_cpu_def->model_id);
> >      x86_cpu_def->vendor_override = 0;
> >  
> > @@ -811,11 +814,13 @@ static void kvm_cpu_fill_host(x86_def_t *x86_cpu_def)
> >          x86_cpu_def->vendor2 == CPUID_VENDOR_VIA_2 &&
> >          x86_cpu_def->vendor3 == CPUID_VENDOR_VIA_3) {
> >          host_cpuid(0xC0000000, 0, &eax, &ebx, &ecx, &edx);
> > +        eax = kvm_arch_get_supported_cpuid(s, 0xC0000000, 0, R_EAX);
> >          if (eax >= 0xC0000001) {
> >              /* Support VIA max extended level */
> >              x86_cpu_def->xlevel2 = eax;
> >              host_cpuid(0xC0000001, 0, &eax, &ebx, &ecx, &edx);
> > -            x86_cpu_def->ext4_features = edx;
> > +            x86_cpu_def->ext4_features =
> > +                    kvm_arch_get_supported_cpuid(s, 0xC0000001, 0, R_EDX);
> >          }
> >      }
> >  
> > 
> 
> 
> -- 
> SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
> GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

-- 
Eduardo