linux-kernel - Re: [PATCH v2 2/5] KVM: MMU: check guest CR3 reserved bits based on its physical address width.

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Date:   Thu, 17 Aug 2017 14:31:11 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Yu Zhang <yu.c.zhang@...ux.intel.com>, kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, rkrcmar@...hat.com,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        xiaoguangrong@...cent.com, joro@...tes.org
Subject: Re: [PATCH v2 2/5] KVM: MMU: check guest CR3 reserved bits based on
 its physical address width.

On 17/08/2017 21:52, Yu Zhang wrote:
> +		if (efer & EFER_LMA) {
> +			u64 maxphyaddr;
> +			u32 eax = 0x80000008;
> +
> +			if (ctxt->ops->get_cpuid(ctxt, &eax, NULL, NULL, NULL,
> +						 NO_CHECK_LIMIT)) {
> +				maxphyaddr = eax & 0xff;
> +				rsvd = rsvd_bits(maxphyaddr, 62);
> +			}

You should use 36 here if ctxt->ops->get_cpuid returns false, for
consistency with cpuid_query_maxphyaddr.

Paolo