linux-kernel - Re: [PATCH v8 050/103] KVM: TDX: Add load_mmu

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Date:   Fri, 2 Sep 2022 15:27:14 +0800
From:   Yuan Yao <yuan.yao@...ux.intel.com>
To:     isaku.yamahata@...el.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
        erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>
Subject: Re: [PATCH v8 050/103] KVM: TDX: Add load_mmu_pgd method for TDX

On Sun, Aug 07, 2022 at 03:01:35PM -0700, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
>
> For virtual IO, the guest TD shares guest pages with VMM without
> encryption.  Shared EPT is used to map guest pages in unprotected way.
>
> Add the VMCS field encoding for the shared EPTP, which will be used by
> TDX to have separate EPT walks for private GPAs (existing EPTP) versus
> shared GPAs (new shared EPTP).
>
> Set shared EPT pointer value for the TDX guest to initialize TDX MMU.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>

Reviewed-by: Yuan Yao <yuan.yao@...el.com>

> ---
>  arch/x86/include/asm/vmx.h |  1 +
>  arch/x86/kvm/vmx/main.c    | 11 ++++++++++-
>  arch/x86/kvm/vmx/tdx.c     |  5 +++++
>  arch/x86/kvm/vmx/x86_ops.h |  4 ++++
>  4 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index f0f8eecf55ac..e169ace97e83 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -234,6 +234,7 @@ enum vmcs_field {
>  	TSC_MULTIPLIER_HIGH             = 0x00002033,
>  	TERTIARY_VM_EXEC_CONTROL	= 0x00002034,
>  	TERTIARY_VM_EXEC_CONTROL_HIGH	= 0x00002035,
> +	SHARED_EPT_POINTER		= 0x0000203C,
>  	PID_POINTER_TABLE		= 0x00002042,
>  	PID_POINTER_TABLE_HIGH		= 0x00002043,
>  	GUEST_PHYSICAL_ADDRESS          = 0x00002400,
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index 9f4c3a0bcc12..252b7298b230 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -110,6 +110,15 @@ static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>  	return vmx_vcpu_reset(vcpu, init_event);
>  }
>
> +static void vt_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
> +			int pgd_level)
> +{
> +	if (is_td_vcpu(vcpu))
> +		return tdx_load_mmu_pgd(vcpu, root_hpa, pgd_level);
> +
> +	vmx_load_mmu_pgd(vcpu, root_hpa, pgd_level);
> +}
> +
>  static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
>  {
>  	if (!is_td(kvm))
> @@ -228,7 +237,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
>  	.write_tsc_offset = vmx_write_tsc_offset,
>  	.write_tsc_multiplier = vmx_write_tsc_multiplier,
>
> -	.load_mmu_pgd = vmx_load_mmu_pgd,
> +	.load_mmu_pgd = vt_load_mmu_pgd,
>
>  	.check_intercept = vmx_check_intercept,
>  	.handle_exit_irqoff = vmx_handle_exit_irqoff,
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 36d2127cb7b7..7a631ae78e59 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -518,6 +518,11 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>  	vcpu->kvm->vm_bugged = true;
>  }
>
> +void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int pgd_level)
> +{
> +	td_vmcs_write64(to_tdx(vcpu), SHARED_EPT_POINTER, root_hpa & PAGE_MASK);
> +}
> +
>  int tdx_dev_ioctl(void __user *argp)
>  {
>  	struct kvm_tdx_capabilities __user *user_caps;
> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index 62f1d1cdd44b..185481ee5f2f 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -145,6 +145,8 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event);
>
>  int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
>  int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
> +
> +void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level);
>  #else
>  static inline int tdx_hardware_setup(struct kvm_x86_ops *x86_ops) { return 0; }
>  static inline bool tdx_is_vm_type_supported(unsigned long type) { return false; }
> @@ -162,6 +164,8 @@ static inline void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) {}
>
>  static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
>  static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }
> +
> +static inline void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level) {}
>  #endif
>
>  #endif /* __KVM_X86_VMX_X86_OPS_H */
> --
> 2.25.1
>