linux-kernel - Re: [PATCH 2/6] KVM: x86: selftests: Define AMD PMU CPUID leaves

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <gsntjzg09tgm.fsf@coltonlewis-kvm.c.googlers.com>
Date: Wed, 28 Aug 2024 22:24:25 +0000
From: Colton Lewis <coltonlewis@...gle.com>
To: Mingwei Zhang <mizhang@...gle.com>
Cc: kvm@...r.kernel.org, ljr.kernel@...il.com, jmattson@...gle.com, 
	aaronlewis@...gle.com, seanjc@...gle.com, pbonzini@...hat.com, 
	shuah@...nel.org, linux-kselftest@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] KVM: x86: selftests: Define AMD PMU CPUID leaves

Hi Mingwei, thanks for reviewing!

Mingwei Zhang <mizhang@...gle.com> writes:

> On Tue, Aug 13, 2024, Colton Lewis wrote:
>> This defined the CPUID calls to determine what extensions and
>> properties are available. AMD reference manual names listed below.

>> * PerfCtrExtCore (six core counters instead of four)
>> * PerfCtrExtNB (four counters for northbridge events)
>> * PerfCtrExtL2I (four counters for L2 cache events)
>> * PerfMonV2 (support for registers to control multiple
>>    counters with a single register write)
>> * LbrAndPmcFreeze (support for freezing last branch recorded stack on
>>    performance counter overflow)
>> * NumPerfCtrCore (number of core counters)
>> * NumPerfCtrNB (number of northbridge counters)

>> Signed-off-by: Colton Lewis <coltonlewis@...gle.com>
>> ---
>>   tools/testing/selftests/kvm/include/x86_64/processor.h | 7 +++++++
>>   1 file changed, 7 insertions(+)

>> diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h  
>> b/tools/testing/selftests/kvm/include/x86_64/processor.h
>> index a0c1440017bb..9d87b5f8974f 100644
>> --- a/tools/testing/selftests/kvm/include/x86_64/processor.h
>> +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
>> @@ -183,6 +183,9 @@ struct kvm_x86_cpu_feature {
>>   #define	X86_FEATURE_GBPAGES		KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 26)
>>   #define	X86_FEATURE_RDTSCP		KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 27)
>>   #define	X86_FEATURE_LM			KVM_X86_CPU_FEATURE(0x80000001, 0, EDX, 29)
>> +#define	X86_FEATURE_PERF_CTR_EXT_CORE	KVM_X86_CPU_FEATURE(0x80000001,  
>> 0, ECX, 23)
>> +#define	X86_FEATURE_PERF_CTR_EXT_NB	KVM_X86_CPU_FEATURE(0x80000001, 0,  
>> ECX, 24)
>> +#define	X86_FEATURE_PERF_CTR_EXT_L2I	KVM_X86_CPU_FEATURE(0x80000001, 0,  
>> ECX, 28)

> You won't be testing Northbridge counters and L2I counters, so these two
> could be optional to the patch.

That's correct. Since it was a small thing to include I thought it best
to include and save someone in the future from digging through the
reference manual again.

When you say "optional" is that an endorsement of deleting?

>>   #define	X86_FEATURE_INVTSC		KVM_X86_CPU_FEATURE(0x80000007, 0, EDX, 8)
>>   #define	X86_FEATURE_RDPRU		KVM_X86_CPU_FEATURE(0x80000008, 0, EBX, 4)
>>   #define	X86_FEATURE_AMD_IBPB		KVM_X86_CPU_FEATURE(0x80000008, 0, EBX,  
>> 12)
>> @@ -195,6 +198,8 @@ struct kvm_x86_cpu_feature {
>>   #define	X86_FEATURE_VGIF		KVM_X86_CPU_FEATURE(0x8000000A, 0, EDX, 16)
>>   #define X86_FEATURE_SEV			KVM_X86_CPU_FEATURE(0x8000001F, 0, EAX, 1)
>>   #define X86_FEATURE_SEV_ES		KVM_X86_CPU_FEATURE(0x8000001F, 0, EAX, 3)
>> +#define	X86_FEATURE_PERF_MON_V2		KVM_X86_CPU_FEATURE(0x80000022, 0,  
>> EAX, 0)

> Let's use X86_FEATURE_PERFMON_V2 instead.

Done

>> +#define	X86_FEATURE_PERF_LBR_PMC_FREEZE	KVM_X86_CPU_FEATURE(0x80000022,  
>> 0, EAX, 2)

> You don't use this feature, do you? If not, this can be optional for the
> patch.

Correct again, included for the same reasoning above.


>>   /*
>>    * KVM defined paravirt features.
>> @@ -281,6 +286,8 @@ struct kvm_x86_cpu_property {
>>   #define X86_PROPERTY_GUEST_MAX_PHY_ADDR		 
>> KVM_X86_CPU_PROPERTY(0x80000008, 0, EAX, 16, 23)
>>   #define X86_PROPERTY_SEV_C_BIT			KVM_X86_CPU_PROPERTY(0x8000001F, 0,  
>> EBX, 0, 5)
>>   #define X86_PROPERTY_PHYS_ADDR_REDUCTION	 
>> KVM_X86_CPU_PROPERTY(0x8000001F, 0, EBX, 6, 11)
>> +#define X86_PROPERTY_NUM_PERF_CTR_CORE		 
>> KVM_X86_CPU_PROPERTY(0x80000022, 0, EBX, 0, 3)
>> +#define X86_PROPERTY_NUM_PERF_CTR_NB		KVM_X86_CPU_PROPERTY(0x80000022,  
>> 0, EBX, 10, 15)


> ditto.
>>   #define X86_PROPERTY_MAX_CENTAUR_LEAF		KVM_X86_CPU_PROPERTY(0xC0000000,  
>> 0, EAX, 0, 31)

>> --
>> 2.46.0.76.ge559c4bf1a-goog