linux-kernel - Re: [PATCH 17/25] KVM: TDX: create/free TDX vcpu structure

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Message-ID: <c03df364-4cce-4c7e-b9db-191f7b10ca70@linux.intel.com>
Date: Tue, 13 Aug 2024 17:15:28 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc: seanjc@...gle.com, pbonzini@...hat.com, kvm@...r.kernel.org,
 kai.huang@...el.com, isaku.yamahata@...il.com,
 tony.lindgren@...ux.intel.com, xiaoyao.li@...el.com,
 linux-kernel@...r.kernel.org, Isaku Yamahata <isaku.yamahata@...el.com>
Subject: Re: [PATCH 17/25] KVM: TDX: create/free TDX vcpu structure




On 8/13/2024 6:48 AM, Rick Edgecombe wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
>
> Implement vcpu related stubs for TDX for create, reset and free.
>
> For now, create only the features that do not require the TDX SEAMCALL.
> The TDX specific vcpu initialization will be handled by KVM_TDX_INIT_VCPU.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
> ---
> uAPI breakout v1:
>   - Dropped unnecessary WARN_ON_ONCE() in tdx_vcpu_create().
>     WARN_ON_ONCE(vcpu->arch.cpuid_entries),
>     WARN_ON_ONCE(vcpu->arch.cpuid_nent)
>   - Use kvm_tdx instead of to_kvm_tdx() in tdx_vcpu_create() (Chao)
>
> v19:
>   - removed stale comment in tdx_vcpu_create().
>
> v18:
>   - update commit log to use create instead of allocate because the patch
>     doesn't newly allocate memory for TDX vcpu.
>
> v16:
>   - Add AMX support as the KVM upstream supports it.
> --
> 2.46.0
> ---
>   arch/x86/kvm/vmx/main.c    | 44 ++++++++++++++++++++++++++++++++++----
>   arch/x86/kvm/vmx/tdx.c     | 41 +++++++++++++++++++++++++++++++++++
>   arch/x86/kvm/vmx/x86_ops.h | 10 +++++++++
>   arch/x86/kvm/x86.c         |  2 ++
>   4 files changed, 93 insertions(+), 4 deletions(-)
>
[...]
> +
> +static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> +{
> +	if (is_td_vcpu(vcpu)) {
> +		tdx_vcpu_reset(vcpu, init_event);
> +		return;
> +	}
> +
> +	vmx_vcpu_reset(vcpu, init_event);
> +}
> +
[...]
> +
> +void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> +{
> +
> +	/* Ignore INIT silently because TDX doesn't support INIT event. */
> +	if (init_event)
> +		return;
> +
> +	/* This is stub for now. More logic will come here. */
> +}
> +
For TDX, it actually doesn't do any thing meaningful in vcpu reset.
Maybe we can drop the helper and move the comments to vt_vcpu_reset()?

>   
>   #endif /* __KVM_X86_VMX_X86_OPS_H */
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index ce2ef63f30f2..9cee326f5e7a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -488,6 +488,7 @@ int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>   	kvm_recalculate_apic_map(vcpu->kvm);
>   	return 0;
>   }
> +EXPORT_SYMBOL_GPL(kvm_set_apic_base);
>   
>   /*
>    * Handle a fault on a hardware virtualization (VMX or SVM) instruction.
> @@ -12630,6 +12631,7 @@ bool kvm_vcpu_is_reset_bsp(struct kvm_vcpu *vcpu)
>   {
>   	return vcpu->kvm->arch.bsp_vcpu_id == vcpu->vcpu_id;
>   }
> +EXPORT_SYMBOL_GPL(kvm_vcpu_is_reset_bsp);
>   
>   bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu)
>   {

kvm_set_apic_base() and kvm_vcpu_is_reset_bsp() is not used in
this patch. The symbol export should move to the next patch, which
uses them.