Re: [PATCH v19 024/130] KVM: TDX: Add placeholders for TDX VM/vcpu structure

Binbin Wu
2024-03-14T06:21:13Z

On 2/26/2024 4:25 PM, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.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@intel.com>
>
> ---
> v19:
> - correctly update ops.vm_size, vcpu_size and, vcpu_align by Xiaoyao
>
> v14 -> v15:
> - use KVM_X86_TDX_VM
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/kvm/vmx/main.c | 14 ++++++++++++
> arch/x86/kvm/vmx/tdx.c | 1 +
> arch/x86/kvm/vmx/tdx.h | 50 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 65 insertions(+)
> 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 18aef6e23aab..e11edbd19e7c 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);
> @@ -18,6 +19,9 @@ static __init int vt_hardware_setup(void)
> return ret;
>
> enable_tdx = enable_tdx && !tdx_hardware_setup(&vt_x86_ops);
> + if (enable_tdx)
> + vt_x86_ops.vm_size = max_t(unsigned int, vt_x86_ops.vm_size,
> + sizeof(struct kvm_tdx));
>
> return 0;
> }
> @@ -215,8 +219,18 @@ static int __init vt_init(void)
> * Common KVM initialization _must_ come last, after this, /dev/kvm is
> * exposed to userspace!
> */
> + /*
> + * kvm_x86_ops is updated with vt_x86_ops. vt_x86_ops.vm_size must
> + * be set before kvm_x86_vendor_init().

The comment is not right?
In this patch, vt_x86_ops.vm_size is set in  vt_hardware_setup(),
which is called in kvm_x86_vendor_init().

Since kvm_x86_ops is updated by kvm_ops_update() with the fields of
vt_x86_ops. I guess you wanted to say vt_x86_ops.vm_size must be set
before kvm_ops_update()?

> + */
> vcpu_size = sizeof(struct vcpu_vmx);
> vcpu_align = __alignof__(struct vcpu_vmx);
> + if (enable_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 = 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 43c504fb4fed..14ef0ccd8f1a 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 */