linux-kernel - Re: [RFC PATCH v5 043/104] KVM: TDX: Add load_mmu

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Message-ID: <d02d9e4c-ebcc-ba6b-f788-7952e437ed69@redhat.com>
Date:   Tue, 5 Apr 2022 16:51:29 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...il.com, Jim Mattson <jmattson@...gle.com>,
        erdemaktas@...gle.com, Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [RFC PATCH v5 043/104] KVM: TDX: Add load_mmu_pgd method for TDX

On 3/4/22 20:48, 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>
> ---
>   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 88d9b8cc7dde..a2402d1bde04 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -221,6 +221,7 @@ enum vmcs_field {
>   	ENCLS_EXITING_BITMAP_HIGH	= 0x0000202F,
>   	TSC_MULTIPLIER                  = 0x00002032,
>   	TSC_MULTIPLIER_HIGH             = 0x00002033,
> +	SHARED_EPT_POINTER		= 0x0000203C,
>   	GUEST_PHYSICAL_ADDRESS          = 0x00002400,
>   	GUEST_PHYSICAL_ADDRESS_HIGH     = 0x00002401,
>   	VMCS_LINK_POINTER               = 0x00002800,
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index b242a9dc9e29..6969e3557bd4 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -89,6 +89,15 @@ 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_op(struct kvm *kvm, void __user *argp)
>   {
>   	if (!is_td(kvm))
> @@ -205,7 +214,7 @@ 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 c3434b33c452..51098e10b6a0 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -496,6 +496,11 @@ 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);
> +}
> +
>   static int tdx_capabilities(struct kvm *kvm, struct kvm_tdx_cmd *cmd)
>   {
>   	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 81f246493ec7..ad9b1c883761 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -143,6 +143,8 @@ 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 void tdx_pre_kvm_init(
>   	unsigned int *vcpu_size, unsigned int *vcpu_align, unsigned int *vm_size) {}
> @@ -160,6 +162,8 @@ 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 */

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