Re: [PATCH v3 5/9] KVM: x86: MMU: Integrate LAM bits when build guest CR3

From: Yuan Yao <yuan.yao@linux.intel.com>
To: Robert Hoo <robert.hu@linux.intel.com>
Cc: pbonzini@redhat.com, seanjc@google.com,
	kirill.shutemov@linux.intel.com, kvm@vger.kernel.org,
	Jingqi Liu <jingqi.liu@intel.com>
Subject: Re: [PATCH v3 5/9] KVM: x86: MMU: Integrate LAM bits when build guest CR3
Date: Mon, 19 Dec 2022 14:53:47 +0800	[thread overview]
Message-ID: <20221219065347.oojvunwaszvqxhu5@yy-desk-7060> (raw)
In-Reply-To: <20221209044557.1496580-6-robert.hu@linux.intel.com>

On Fri, Dec 09, 2022 at 12:45:53PM +0800, Robert Hoo wrote:
> When calc the new CR3 value, take LAM bits in.
>
> Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
> Reviewed-by: Jingqi Liu <jingqi.liu@intel.com>
> ---
>  arch/x86/kvm/mmu.h     | 5 +++++
>  arch/x86/kvm/vmx/vmx.c | 3 ++-
>  2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 6bdaacb6faa0..866f2b7cb509 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -142,6 +142,11 @@ static inline unsigned long kvm_get_active_pcid(struct kvm_vcpu *vcpu)
>  	return kvm_get_pcid(vcpu, kvm_read_cr3(vcpu));
>  }
>
> +static inline u64 kvm_get_active_lam(struct kvm_vcpu *vcpu)
> +{

Unlike the PCIDs, LAM bits in CR3 are  not sharing with other features,
(e.g. PCID vs non-PCIN on bit 0:11) so not check CR4[28] here should
be fine, otherwise follows kvm_get_pcid() looks better.

> +	return kvm_read_cr3(vcpu) & (X86_CR3_LAM_U48 | X86_CR3_LAM_U57);
> +}
> +
>  static inline void kvm_mmu_load_pgd(struct kvm_vcpu *vcpu)
>  {
>  	u64 root_hpa = vcpu->arch.mmu->root.hpa;
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index cfa06c7c062e..9985dbb63e7b 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -3261,7 +3261,8 @@ static void vmx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
>  			update_guest_cr3 = false;
>  		vmx_ept_load_pdptrs(vcpu);
>  	} else {
> -		guest_cr3 = root_hpa | kvm_get_active_pcid(vcpu);
> +		guest_cr3 = root_hpa | kvm_get_active_pcid(vcpu) |
> +			    kvm_get_active_lam(vcpu);
>  	}
>
>  	if (update_guest_cr3)
> --
> 2.31.1
>