Re: [PATCH v13 016/113] KVM: TDX: x86: Add ioctl to get TDX systemwide parameters

[Isaku Yamahata]

On Sat, Mar 25, 2023 at 10:43:06AM +0200,
Zhi Wang <zhi.wang.linux@xxxxxxxxx> wrote:

> On Sun, 12 Mar 2023 10:55:40 -0700
> isaku.yamahata@xxxxxxxxx wrote:
> 
> Does this have to be a new generic ioctl with a dedicated new x86_ops? SNP
> does not use it at all and all the system-scoped ioctl of SNP going through
> the CCP driver. So getting system-scope information of TDX/SNP will end up
> differently.
> 
> Any thought, Sean? Moving getting SNP system-wide information to
> KVM dev ioctl seems not ideal and TDX does not have a dedicated driver like
> CCP. Maybe make this ioctl TDX-specific? KVM_TDX_DEV_OP?

We only need global parameters of the TDX module, and we don't interact with TDX
module at this point.  One alternative is to export those parameters via sysfs.
Also the existence of the sysfs node indicates that the TDX module is
loaded(initialized?) or not in addition to boot log.  Thus we can drop system
scope one.
What do you think?

Regarding to other TDX KVM specific ioctls (KVM_TDX_INIT_VM, KVM_TDX_INIT_VCPU,
KVM_TDX_INIT_MEM_REGION, and KVM_TDX_FINALIZE_VM), they are specific to KVM.  So
I don't think it can be split out to independent driver.

Thanks,

> > From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> > 
> > Implement a system-scoped ioctl to get system-wide parameters for TDX.
> > 
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> > ---
> >  arch/x86/include/asm/kvm-x86-ops.h    |  1 +
> >  arch/x86/include/asm/kvm_host.h       |  1 +
> >  arch/x86/include/uapi/asm/kvm.h       | 48 +++++++++++++++++++++++++
> >  arch/x86/kvm/vmx/main.c               |  2 ++
> >  arch/x86/kvm/vmx/tdx.c                | 51 +++++++++++++++++++++++++++
> >  arch/x86/kvm/vmx/x86_ops.h            |  2 ++
> >  arch/x86/kvm/x86.c                    |  6 ++++
> >  tools/arch/x86/include/uapi/asm/kvm.h | 48 +++++++++++++++++++++++++
> >  8 files changed, 159 insertions(+)
> > 
> > diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
> > index eac4b65d1b01..b46dcac078b2 100644
> > --- a/arch/x86/include/asm/kvm-x86-ops.h
> > +++ b/arch/x86/include/asm/kvm-x86-ops.h
> > @@ -117,6 +117,7 @@ KVM_X86_OP(enter_smm)
> >  KVM_X86_OP(leave_smm)
> >  KVM_X86_OP(enable_smi_window)
> >  #endif
> > +KVM_X86_OP_OPTIONAL(dev_mem_enc_ioctl)
> >  KVM_X86_OP_OPTIONAL(mem_enc_ioctl)
> >  KVM_X86_OP_OPTIONAL(mem_enc_register_region)
> >  KVM_X86_OP_OPTIONAL(mem_enc_unregister_region)
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 00c25f6ab871..49e3ca89aced 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -1719,6 +1719,7 @@ struct kvm_x86_ops {
> >  	void (*enable_smi_window)(struct kvm_vcpu *vcpu);
> >  #endif
> >  
> > +	int (*dev_mem_enc_ioctl)(void __user *argp);
> >  	int (*mem_enc_ioctl)(struct kvm *kvm, void __user *argp);
> >  	int (*mem_enc_register_region)(struct kvm *kvm, struct kvm_enc_region *argp);
> >  	int (*mem_enc_unregister_region)(struct kvm *kvm, struct kvm_enc_region *argp);
> > diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> > index 6afbfbb32d56..af4c5bd0af1c 100644
> > --- a/arch/x86/include/uapi/asm/kvm.h
> > +++ b/arch/x86/include/uapi/asm/kvm.h
> > @@ -562,4 +562,52 @@ struct kvm_pmu_event_filter {
> >  #define KVM_X86_DEFAULT_VM	0
> >  #define KVM_X86_PROTECTED_VM	1
> >  
> > +/* Trust Domain eXtension sub-ioctl() commands. */
> > +enum kvm_tdx_cmd_id {
> > +	KVM_TDX_CAPABILITIES = 0,
> > +
> > +	KVM_TDX_CMD_NR_MAX,
> > +};
> > +
> > +struct kvm_tdx_cmd {
> > +	/* enum kvm_tdx_cmd_id */
> > +	__u32 id;
> > +	/* flags for sub-commend. If sub-command doesn't use this, set zero. */
> > +	__u32 flags;
> > +	/*
> > +	 * data for each sub-command. An immediate or a pointer to the actual
> > +	 * data in process virtual address.  If sub-command doesn't use it,
> > +	 * set zero.
> > +	 */
> > +	__u64 data;
> > +	/*
> > +	 * Auxiliary error code.  The sub-command may return TDX SEAMCALL
> > +	 * status code in addition to -Exxx.
> > +	 * Defined for consistency with struct kvm_sev_cmd.
> > +	 */
> > +	__u64 error;
> > +	/* Reserved: Defined for consistency with struct kvm_sev_cmd. */
> > +	__u64 unused;
> > +};
> > +
> > +struct kvm_tdx_cpuid_config {
> > +	__u32 leaf;
> > +	__u32 sub_leaf;
> > +	__u32 eax;
> > +	__u32 ebx;
> > +	__u32 ecx;
> > +	__u32 edx;
> > +};
> > +
> > +struct kvm_tdx_capabilities {
> > +	__u64 attrs_fixed0;
> > +	__u64 attrs_fixed1;
> > +	__u64 xfam_fixed0;
> > +	__u64 xfam_fixed1;
> > +
> > +	__u32 nr_cpuid_configs;
> > +	__u32 padding;
> > +	struct kvm_tdx_cpuid_config cpuid_configs[0];
> > +};
> > +
> >  #endif /* _ASM_X86_KVM_H */
> > diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> > index c8548004802a..6a5d0c7a2950 100644
> > --- a/arch/x86/kvm/vmx/main.c
> > +++ b/arch/x86/kvm/vmx/main.c
> > @@ -201,6 +201,8 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
> >  	.complete_emulated_msr = kvm_complete_insn_gp,
> >  
> >  	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
> > +
> > +	.dev_mem_enc_ioctl = tdx_dev_ioctl,
> >  };
> >  
> >  struct kvm_x86_init_ops vt_init_ops __initdata = {
> > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> > index e9b7aa5654e9..b59d3081d061 100644
> > --- a/arch/x86/kvm/vmx/tdx.c
> > +++ b/arch/x86/kvm/vmx/tdx.c
> > @@ -21,6 +21,57 @@ int tdx_hardware_enable(void)
> >  	return tdx_cpu_enable();
> >  }
> >  
> > +int tdx_dev_ioctl(void __user *argp)
> > +{
> > +	struct kvm_tdx_capabilities __user *user_caps;
> > +	const struct tdsysinfo_struct *tdsysinfo;
> > +	struct kvm_tdx_capabilities caps;
> > +	struct kvm_tdx_cmd cmd;
> > +
> > +	BUILD_BUG_ON(sizeof(struct kvm_tdx_cpuid_config) !=
> > +		     sizeof(struct tdx_cpuid_config));
> > +
> > +	if (copy_from_user(&cmd, argp, sizeof(cmd)))
> > +		return -EFAULT;
> > +	if (cmd.flags || cmd.error || cmd.unused)
> > +		return -EINVAL;
> > +	/*
> > +	 * Currently only KVM_TDX_CAPABILITIES is defined for system-scoped
> > +	 * mem_enc_ioctl().
> > +	 */
> > +	if (cmd.id != KVM_TDX_CAPABILITIES)
> > +		return -EINVAL;
> > +
> > +	tdsysinfo = tdx_get_sysinfo();
> > +	if (!tdsysinfo)
> > +		return -ENOTSUPP;
> > +
> > +	user_caps = (void __user *)cmd.data;
> > +	if (copy_from_user(&caps, user_caps, sizeof(caps)))
> > +		return -EFAULT;
> > +
> > +	if (caps.nr_cpuid_configs < tdsysinfo->num_cpuid_config)
> > +		return -E2BIG;
> > +
> > +	caps = (struct kvm_tdx_capabilities) {
> > +		.attrs_fixed0 = tdsysinfo->attributes_fixed0,
> > +		.attrs_fixed1 = tdsysinfo->attributes_fixed1,
> > +		.xfam_fixed0 = tdsysinfo->xfam_fixed0,
> > +		.xfam_fixed1 = tdsysinfo->xfam_fixed1,
> > +		.nr_cpuid_configs = tdsysinfo->num_cpuid_config,
> > +		.padding = 0,
> > +	};
> > +
> > +	if (copy_to_user(user_caps, &caps, sizeof(caps)))
> > +		return -EFAULT;
> > +	if (copy_to_user(user_caps->cpuid_configs, &tdsysinfo->cpuid_configs,
> > +			 tdsysinfo->num_cpuid_config *
> > +			 sizeof(struct tdx_cpuid_config)))
> > +		return -EFAULT;
> > +
> > +	return 0;
> > +}
> > +
> >  static int __init tdx_module_setup(void)
> >  {
> >  	const struct tdsysinfo_struct *tdsysinfo;
> > diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> > index b2c74c1b5bbd..78c5537e23a1 100644
> > --- a/arch/x86/kvm/vmx/x86_ops.h
> > +++ b/arch/x86/kvm/vmx/x86_ops.h
> > @@ -141,10 +141,12 @@ void vmx_setup_mce(struct kvm_vcpu *vcpu);
> >  int __init tdx_hardware_setup(struct kvm_x86_ops *x86_ops);
> >  int tdx_hardware_enable(void);
> >  bool tdx_is_vm_type_supported(unsigned long type);
> > +int tdx_dev_ioctl(void __user *argp);
> >  #else
> >  static inline int tdx_hardware_setup(struct kvm_x86_ops *x86_ops) { return -ENOSYS; }
> >  static inline int tdx_hardware_enable(void) { return -EOPNOTSUPP; }
> >  static inline bool tdx_is_vm_type_supported(unsigned long type) { return false; }
> > +static inline int tdx_dev_ioctl(void __user *argp) { return -EOPNOTSUPP; };
> >  #endif
> >  
> >  #endif /* __KVM_X86_VMX_X86_OPS_H */
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 27ab684f8374..a3dc32e33aca 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -4718,6 +4718,12 @@ long kvm_arch_dev_ioctl(struct file *filp,
> >  		r = kvm_x86_dev_has_attr(&attr);
> >  		break;
> >  	}
> > +	case KVM_MEMORY_ENCRYPT_OP:
> > +		r = -EINVAL;
> > +		if (!kvm_x86_ops.dev_mem_enc_ioctl)
> > +			goto out;
> > +		r = static_call(kvm_x86_dev_mem_enc_ioctl)(argp);
> > +		break;
> >  	default:
> >  		r = -EINVAL;
> >  		break;
> > diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
> > index 6afbfbb32d56..af4c5bd0af1c 100644
> > --- a/tools/arch/x86/include/uapi/asm/kvm.h
> > +++ b/tools/arch/x86/include/uapi/asm/kvm.h
> > @@ -562,4 +562,52 @@ struct kvm_pmu_event_filter {
> >  #define KVM_X86_DEFAULT_VM	0
> >  #define KVM_X86_PROTECTED_VM	1
> >  
> > +/* Trust Domain eXtension sub-ioctl() commands. */
> > +enum kvm_tdx_cmd_id {
> > +	KVM_TDX_CAPABILITIES = 0,
> > +
> > +	KVM_TDX_CMD_NR_MAX,
> > +};
> > +
> > +struct kvm_tdx_cmd {
> > +	/* enum kvm_tdx_cmd_id */
> > +	__u32 id;
> > +	/* flags for sub-commend. If sub-command doesn't use this, set zero. */
> > +	__u32 flags;
> > +	/*
> > +	 * data for each sub-command. An immediate or a pointer to the actual
> > +	 * data in process virtual address.  If sub-command doesn't use it,
> > +	 * set zero.
> > +	 */
> > +	__u64 data;
> > +	/*
> > +	 * Auxiliary error code.  The sub-command may return TDX SEAMCALL
> > +	 * status code in addition to -Exxx.
> > +	 * Defined for consistency with struct kvm_sev_cmd.
> > +	 */
> > +	__u64 error;
> > +	/* Reserved: Defined for consistency with struct kvm_sev_cmd. */
> > +	__u64 unused;
> > +};
> > +
> > +struct kvm_tdx_cpuid_config {
> > +	__u32 leaf;
> > +	__u32 sub_leaf;
> > +	__u32 eax;
> > +	__u32 ebx;
> > +	__u32 ecx;
> > +	__u32 edx;
> > +};
> > +
> > +struct kvm_tdx_capabilities {
> > +	__u64 attrs_fixed0;
> > +	__u64 attrs_fixed1;
> > +	__u64 xfam_fixed0;
> > +	__u64 xfam_fixed1;
> > +
> > +	__u32 nr_cpuid_configs;
> > +	__u32 padding;
> > +	struct kvm_tdx_cpuid_config cpuid_configs[0];
> > +};
> > +
> >  #endif /* _ASM_X86_KVM_H */
> 

-- 
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>