Re: [PATCH v6 06/19] i386: introduce hv_cpuid_get_host()

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Eduardo Habkost <ehabkost@redhat.com> writes:

> On Thu, Apr 22, 2021 at 06:11:17PM +0200, Vitaly Kuznetsov wrote:
>> As a preparation to implementing hv_cpuid_cache intro introduce
>> hv_cpuid_get_host(). No functional change intended.
>> 
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>> ---
>>  target/i386/kvm/kvm.c | 102 +++++++++++++++++++++++-------------------
>>  1 file changed, 57 insertions(+), 45 deletions(-)
>> 
>> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
>> index ba093dba4d23..7aeb704b016e 100644
>> --- a/target/i386/kvm/kvm.c
>> +++ b/target/i386/kvm/kvm.c
>> @@ -1107,6 +1107,19 @@ static int hv_cpuid_get_fw(struct kvm_cpuid2 *cpuid, int fw, uint32_t *r)
>>      return 0;
>>  }
>>  
>> +static uint32_t hv_cpuid_get_host(struct kvm_cpuid2 *cpuid, uint32_t func,
>> +                                  int reg)
>> +{
>> +    struct kvm_cpuid_entry2 *entry;
>> +
>> +    entry = cpuid_find_entry(cpuid, func, 0);
>> +    if (!entry) {
>> +        return 0;
>
> One possible difference here is that leaves not supported by the
> host will now be zeroed out.
>
> ...which I expected to be the correct behavior of hv-passthrough,

Yes, at least that's the intention.

> so:
>
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
>

Thanks!

>
>> +    }
>> +
>> +    return cpuid_entry_get_reg(entry, reg);
>> +}
>> +
>>  static bool hyperv_feature_supported(struct kvm_cpuid2 *cpuid, int feature)
>>  {
>>      uint32_t r, fw, bits;
>> @@ -1203,7 +1216,7 @@ static int hyperv_handle_properties(CPUState *cs,
>>  {
>>      X86CPU *cpu = X86_CPU(cs);
>>      struct kvm_cpuid2 *cpuid;
>> -    struct kvm_cpuid_entry2 *c, *c2;
>> +    struct kvm_cpuid_entry2 *c;
>>      uint32_t cpuid_i = 0;
>>      int r;
>>  
>> @@ -1235,46 +1248,47 @@ static int hyperv_handle_properties(CPUState *cs,
>>      }
>>  
>>      if (cpu->hyperv_passthrough) {
>> -        c = cpuid_find_entry(cpuid, HV_CPUID_VENDOR_AND_MAX_FUNCTIONS, 0);
>> -        if (c) {
>> -            cpu->hyperv_vendor_id[0] = c->ebx;
>> -            cpu->hyperv_vendor_id[1] = c->ecx;
>> -            cpu->hyperv_vendor_id[2] = c->edx;
>> -            cpu->hyperv_vendor = g_realloc(cpu->hyperv_vendor,
>> -                                           sizeof(cpu->hyperv_vendor_id) + 1);
>> -            memcpy(cpu->hyperv_vendor, cpu->hyperv_vendor_id,
>> -                   sizeof(cpu->hyperv_vendor_id));
>> -            cpu->hyperv_vendor[sizeof(cpu->hyperv_vendor_id)] = 0;
>> -        }
>> -
>> -        c = cpuid_find_entry(cpuid, HV_CPUID_INTERFACE, 0);
>> -        if (c) {
>> -            cpu->hyperv_interface_id[0] = c->eax;
>> -            cpu->hyperv_interface_id[1] = c->ebx;
>> -            cpu->hyperv_interface_id[2] = c->ecx;
>> -            cpu->hyperv_interface_id[3] = c->edx;
>> -        }
>> -
>> -        c = cpuid_find_entry(cpuid, HV_CPUID_VERSION, 0);
>> -        if (c) {
>> -            cpu->hyperv_version_id[0] = c->eax;
>> -            cpu->hyperv_version_id[1] = c->ebx;
>> -            cpu->hyperv_version_id[2] = c->ecx;
>> -            cpu->hyperv_version_id[3] = c->edx;
>> -        }
>> -
>> -        c = cpuid_find_entry(cpuid, HV_CPUID_IMPLEMENT_LIMITS, 0);
>> -        if (c) {
>> -            cpu->hv_max_vps = c->eax;
>> -            cpu->hyperv_limits[0] = c->ebx;
>> -            cpu->hyperv_limits[1] = c->ecx;
>> -            cpu->hyperv_limits[2] = c->edx;
>> -        }
>> -
>> -        c = cpuid_find_entry(cpuid, HV_CPUID_ENLIGHTMENT_INFO, 0);
>> -        if (c) {
>> -            cpu->hyperv_spinlock_attempts = c->ebx;
>> -        }
>> +        cpu->hyperv_vendor_id[0] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_VENDOR_AND_MAX_FUNCTIONS, R_EBX);
>> +        cpu->hyperv_vendor_id[1] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_VENDOR_AND_MAX_FUNCTIONS, R_ECX);
>> +        cpu->hyperv_vendor_id[2] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_VENDOR_AND_MAX_FUNCTIONS, R_EDX);
>> +        cpu->hyperv_vendor = g_realloc(cpu->hyperv_vendor,
>> +                                       sizeof(cpu->hyperv_vendor_id) + 1);
>> +        memcpy(cpu->hyperv_vendor, cpu->hyperv_vendor_id,
>> +               sizeof(cpu->hyperv_vendor_id));
>> +        cpu->hyperv_vendor[sizeof(cpu->hyperv_vendor_id)] = 0;
>> +
>> +        cpu->hyperv_interface_id[0] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_INTERFACE, R_EAX);
>> +        cpu->hyperv_interface_id[1] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_INTERFACE, R_EBX);
>> +        cpu->hyperv_interface_id[2] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_INTERFACE, R_ECX);
>> +        cpu->hyperv_interface_id[3] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_INTERFACE, R_EDX);
>> +
>> +        cpu->hyperv_version_id[0] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_VERSION, R_EAX);
>> +        cpu->hyperv_version_id[1] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_VERSION, R_EBX);
>> +        cpu->hyperv_version_id[2] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_VERSION, R_ECX);
>> +        cpu->hyperv_version_id[3] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_VERSION, R_EDX);
>> +
>> +        cpu->hv_max_vps = hv_cpuid_get_host(cpuid, HV_CPUID_IMPLEMENT_LIMITS,
>> +                                            R_EAX);
>> +        cpu->hyperv_limits[0] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_IMPLEMENT_LIMITS, R_EBX);
>> +        cpu->hyperv_limits[1] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_IMPLEMENT_LIMITS, R_ECX);
>> +        cpu->hyperv_limits[2] =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_IMPLEMENT_LIMITS, R_EDX);
>> +
>> +        cpu->hyperv_spinlock_attempts =
>> +            hv_cpuid_get_host(cpuid, HV_CPUID_ENLIGHTMENT_INFO, R_EBX);
>>      }
>>  
>>      /* Features */
>> @@ -1348,10 +1362,8 @@ static int hyperv_handle_properties(CPUState *cs,
>>      if (cpu->hyperv_no_nonarch_cs == ON_OFF_AUTO_ON) {
>>          c->eax |= HV_NO_NONARCH_CORESHARING;
>>      } else if (cpu->hyperv_no_nonarch_cs == ON_OFF_AUTO_AUTO) {
>> -        c2 = cpuid_find_entry(cpuid, HV_CPUID_ENLIGHTMENT_INFO, 0);
>> -        if (c2) {
>> -            c->eax |= c2->eax & HV_NO_NONARCH_CORESHARING;
>> -        }
>> +        c->eax |= hv_cpuid_get_host(cpuid, HV_CPUID_ENLIGHTMENT_INFO, R_EAX) &
>> +            HV_NO_NONARCH_CORESHARING;
>>      }
>>  
>>      c = &cpuid_ent[cpuid_i++];
>> -- 
>> 2.30.2
>> 

-- 
Vitaly