From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 04/12] KVM: x86: Validate guest writes to MSR_IA32_APICBASE
Date: Thu, 16 Jan 2014 15:07:15 +0100
Message-ID: <52D7E793.5080005@redhat.com>
References: <cover.1388857646.git.jan.kiszka@web.de> <158b5c8094a923e76ba3aff41052408efa8429df.1388857646.git.jan.kiszka@web.de>
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Cc: Gleb Natapov <gleb@kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	kvm <kvm@vger.kernel.org>
To: Jan Kiszka <jan.kiszka@web.de>
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Il 04/01/2014 18:47, Jan Kiszka ha scritto:
> +	u64 old_state = vcpu->arch.apic_base &
> +		(MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE);
> +	u64 new_state = msr_info->data &
> +		(MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE);
> +	u64 reserved_bits = ((~0ULL) << boot_cpu_data.x86_phys_bits) | 0x2ff |
> +		(guest_cpuid_has_x2apic(vcpu) ? 0 : X2APIC_ENABLE);
> +

Should this use the guest CPUID instead?

> +	if (!msr_info->host_initiated &&

Is this check on host_initiated just for backwards compatibility, or is
there another case that I am missing?

Paolo