linux-kernel - Re: [PATCH v18 009/121] KVM: TDX: Add placeholders for TDX VM/vcpu structure

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Date: Thu, 1 Feb 2024 17:39:30 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: isaku.yamahata@...el.com, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
 erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
 Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
 chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com
Subject: Re: [PATCH v18 009/121] KVM: TDX: Add placeholders for TDX VM/vcpu
 structure

On 1/23/2024 7:52 AM, isaku.yamahata@...el.com wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
> 
> Add placeholders TDX VM/vcpu structure that overlays with VMX VM/vcpu
> structures.  Initialize VM structure size and vcpu size/align so that x86
> KVM common code knows those size irrespective of VMX or TDX.  Those
> structures will be populated as guest creation logic develops.
> 
> Add helper functions to check if the VM is guest TD and add conversion
> functions between KVM VM/VCPU and TDX VM/VCPU.
> 
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> 
> ---
> v14 -> v15:
> - use KVM_X86_TDX_VM
> ---
>   arch/x86/kvm/vmx/main.c | 18 +++++++++++++--
>   arch/x86/kvm/vmx/tdx.c  |  1 +
>   arch/x86/kvm/vmx/tdx.h  | 50 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 67 insertions(+), 2 deletions(-)
>   create mode 100644 arch/x86/kvm/vmx/tdx.h
> 
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index 1e1feaacac59..f6b66f18c070 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -5,6 +5,7 @@
>   #include "vmx.h"
>   #include "nested.h"
>   #include "pmu.h"
> +#include "tdx.h"
>   
>   static bool enable_tdx __ro_after_init;
>   module_param_named(tdx, enable_tdx, bool, 0444);
> @@ -216,6 +217,21 @@ static int __init vt_init(void)
>   	 */
>   	hv_init_evmcs();
>   
> +	/*
> +	 * kvm_x86_ops is updated with vt_x86_ops.  vt_x86_ops.vm_size must
> +	 * be set before kvm_x86_vendor_init().
> +	 */
> +	vcpu_size = sizeof(struct vcpu_vmx);
> +	vcpu_align = __alignof__(struct vcpu_vmx);
> +	if (enable_tdx) {

until now, 'enable_tdx' is totally decided by module_param, which might 
change from Y to N if tdx fails enabling. In this case, the below should 
not be updated.

> +		vt_x86_ops.vm_size = max_t(unsigned int, vt_x86_ops.vm_size,
> +					   sizeof(struct kvm_tdx));
> +		vcpu_size = max_t(unsigned int, vcpu_size,
> +				  sizeof(struct vcpu_tdx));
> +		vcpu_align = max_t(unsigned int, vcpu_align,
> +				   __alignof__(struct vcpu_tdx));
> +	}
> +
>   	r = vmx_init();
>   	if (r)
>   		goto err_vmx_init;
> @@ -228,8 +244,6 @@ static int __init vt_init(void)
>   	 * Common KVM initialization _must_ come last, after this, /dev/kvm is
>   	 * exposed to userspace!
>   	 */
> -	vcpu_size = sizeof(struct vcpu_vmx);
> -	vcpu_align = __alignof__(struct vcpu_vmx);
>   	r = kvm_init(vcpu_size, vcpu_align, THIS_MODULE);
>   	if (r)
>   		goto err_kvm_init;
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 8a378fb6f1d4..1c9884164566 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -6,6 +6,7 @@
>   #include "capabilities.h"
>   #include "x86_ops.h"
>   #include "x86.h"
> +#include "tdx.h"
>   
>   #undef pr_fmt
>   #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> diff --git a/arch/x86/kvm/vmx/tdx.h b/arch/x86/kvm/vmx/tdx.h
> new file mode 100644
> index 000000000000..473013265bd8
> --- /dev/null
> +++ b/arch/x86/kvm/vmx/tdx.h
> @@ -0,0 +1,50 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __KVM_X86_TDX_H
> +#define __KVM_X86_TDX_H
> +
> +#ifdef CONFIG_INTEL_TDX_HOST
> +struct kvm_tdx {
> +	struct kvm kvm;
> +	/* TDX specific members follow. */
> +};
> +
> +struct vcpu_tdx {
> +	struct kvm_vcpu	vcpu;
> +	/* TDX specific members follow. */
> +};
> +
> +static inline bool is_td(struct kvm *kvm)
> +{
> +	return kvm->arch.vm_type == KVM_X86_TDX_VM;
> +}
> +
> +static inline bool is_td_vcpu(struct kvm_vcpu *vcpu)
> +{
> +	return is_td(vcpu->kvm);
> +}
> +
> +static inline struct kvm_tdx *to_kvm_tdx(struct kvm *kvm)
> +{
> +	return container_of(kvm, struct kvm_tdx, kvm);
> +}
> +
> +static inline struct vcpu_tdx *to_tdx(struct kvm_vcpu *vcpu)
> +{
> +	return container_of(vcpu, struct vcpu_tdx, vcpu);
> +}
> +#else
> +struct kvm_tdx {
> +	struct kvm kvm;
> +};
> +
> +struct vcpu_tdx {
> +	struct kvm_vcpu	vcpu;
> +};
> +
> +static inline bool is_td(struct kvm *kvm) { return false; }
> +static inline bool is_td_vcpu(struct kvm_vcpu *vcpu) { return false; }
> +static inline struct kvm_tdx *to_kvm_tdx(struct kvm *kvm) { return NULL; }
> +static inline struct vcpu_tdx *to_tdx(struct kvm_vcpu *vcpu) { return NULL; }
> +#endif /* CONFIG_INTEL_TDX_HOST */
> +
> +#endif /* __KVM_X86_TDX_H */