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Subject: Re: [PATCH v3 3/4] KVM: VMX: Emulate MSR_IA32_ARCH_CAPABILITIES
To:     KarimAllah Ahmed <karahmed@amazon.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        KarimAllah Ahmed <karahmed@amazon.de>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org,
        Asit Mallick <asit.k.mallick@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@intel.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andi Kleen <ak@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Dan Williams <dan.j.williams@intel.com>,
        Jun Nakajima <jun.nakajima@intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        David Woodhouse <dwmw@amazon.co.uk>
References: <1517271028-15916-1-git-send-email-karahmed@amazon.de>
 <1517271028-15916-4-git-send-email-karahmed@amazon.de>
 <20180130002218.GA112596@otc-nc-03>
 <87b28856-c477-283f-695c-daed42b31287@amazon.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <2aaedc76-b407-15f9-7712-535e08153a26@redhat.com>
Date:   Tue, 30 Jan 2018 18:21:47 -0500
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On 29/01/2018 19:25, KarimAllah Ahmed wrote:
>>> +    case MSR_IA32_ARCH_CAPABILITIES:
>>> +        if (!msr_info->host_initiated)
>>> +            return 1;
>>> +        vmx->arch_capabilities = data;
>>> +        break;
>>
>> arch capabilities is read only. You don't need the set_msr handling
>> for this.
> 
> This is only for host driven writes. This would allow QEMU/whatever to
> override the default value (i.e. the value from the hardware).

Agreed.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>