Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:
> On Fri, May 29, 2020 at 03:04:06PM +0200, Vitaly Kuznetsov wrote:
>> More tests may want to check if the CPU is Intel or AMD in
>> guest code, separate cpu_has_svm() and put it as static
>> inline to svm_util.h.
>>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>> ---
>> tools/testing/selftests/kvm/include/x86_64/svm_util.h | 10 ++++++++++
>> tools/testing/selftests/kvm/x86_64/state_test.c | 9 +--------
>> 2 files changed, 11 insertions(+), 8 deletions(-)
>>
>> diff --git a/tools/testing/selftests/kvm/include/x86_64/svm_util.h b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
>> index cd037917fece..b1057773206a 100644
>> --- a/tools/testing/selftests/kvm/include/x86_64/svm_util.h
>> +++ b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
>> @@ -35,4 +35,14 @@ void generic_svm_setup(struct svm_test_data *svm, void *guest_rip, void *guest_r
>> void run_guest(struct vmcb *vmcb, uint64_t vmcb_gpa);
>> void nested_svm_check_supported(void);
>>
>> +static inline bool cpu_has_svm(void)
>> +{
>> + u32 eax = 0x80000001, ecx;
>> +
>> + asm volatile("cpuid" :
>> + "=a" (eax), "=c" (ecx) : "0" (eax) : "ebx", "edx");
>
> u32 eax, ecx;
>
> asm("cpuid" : "=a" (eax), "=c" (ecx) : "a" (0x80000001) : "ebx", "edx");
>
> The volatile shouldn't be needed, e.g. no one should be using this purely
> for its seralization properties, and I don't see any reason to put the leaf
> number into a variable.
>
> Alternatively, adding a proper cpuid framework to processor.h would likely
> be useful in the long run.
>
All true, even better would be to find a way to include the definition
of native_cpuid*() from arch/x86/include/asm/processor.h but I didn't
explore these options yet, was trying to address the immediate issue
with Paolo's SVM series. It can probably be done when there is a second
user of cpuid in tests which needs to check something different from SVM
bit.
--
Vitaly
