linux-kernel - Re: [PATCH v5 09/26] KVM: VMX: nVMX: Support TSC scaling and PERF_GLOBAL

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: <87zgg0smqr.fsf@redhat.com>
Date:   Fri, 19 Aug 2022 09:42:20 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Anirudh Rayabharam <anrayabh@...ux.microsoft.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Michael Kelley <mikelley@...rosoft.com>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 09/26] KVM: VMX: nVMX: Support TSC scaling and
 PERF_GLOBAL_CTRL with enlightened VMCS

Sean Christopherson <seanjc@...gle.com> writes:

> On Tue, Aug 02, 2022, Vitaly Kuznetsov wrote:
>> diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
>> index f886a8ff0342..4b809c79ae63 100644
>> --- a/arch/x86/kvm/vmx/evmcs.h
>> +++ b/arch/x86/kvm/vmx/evmcs.h
>> @@ -37,16 +37,9 @@ DECLARE_STATIC_KEY_FALSE(enable_evmcs);
>>   *	EPTP_LIST_ADDRESS               = 0x00002024,
>>   *	VMREAD_BITMAP                   = 0x00002026,
>>   *	VMWRITE_BITMAP                  = 0x00002028,
>> - *
>> - *	TSC_MULTIPLIER                  = 0x00002032,
>>   *	PLE_GAP                         = 0x00004020,
>>   *	PLE_WINDOW                      = 0x00004022,
>>   *	VMX_PREEMPTION_TIMER_VALUE      = 0x0000482E,
>> - *      GUEST_IA32_PERF_GLOBAL_CTRL     = 0x00002808,
>> - *      HOST_IA32_PERF_GLOBAL_CTRL      = 0x00002c04,
>> - *
>> - * Currently unsupported in KVM:
>> - *	GUEST_IA32_RTIT_CTL		= 0x00002814,
>
> Almost forgot: is deleting this chunk of the comment intentional?
>

Intentional or not (I forgot :-), GUEST_IA32_RTIT_CTL is supported/used
by KVM since

commit f99e3daf94ff35dd4a878d32ff66e1fd35223ad6
Author: Chao Peng <chao.p.peng@...ux.intel.com>
Date:   Wed Oct 24 16:05:10 2018 +0800

    KVM: x86: Add Intel PT virtualization work mode

...
 
commit bf8c55d8dc094c85a3f98cd302a4dddb720dd63f
Author: Chao Peng <chao.p.peng@...ux.intel.com>
Date:   Wed Oct 24 16:05:14 2018 +0800

    KVM: x86: Implement Intel PT MSRs read/write emulation

but there's no corresponding field in eVMCS. It would probably be better
to remove "Currently unsupported in KVM:" line leaving

"GUEST_IA32_RTIT_CTL             = 0x00002814" 

in place. 

-- 
Vitaly