linux-kernel - Re: [PATCH v12 12/23] KVM: selftests: Add helper to initialize TDX VM

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Message-ID: <6902844729ad2_21ab5210055@iweiny-mobl.notmuch>
Date: Wed, 29 Oct 2025 16:16:55 -0500
From: Ira Weiny <ira.weiny@...el.com>
To: Sagi Shahar <sagis@...gle.com>, <linux-kselftest@...r.kernel.org>, "Paolo
 Bonzini" <pbonzini@...hat.com>, Shuah Khan <shuah@...nel.org>, "Sean
 Christopherson" <seanjc@...gle.com>, Ackerley Tng <ackerleytng@...gle.com>,
	Ryan Afranji <afranji@...gle.com>, Andrew Jones <ajones@...tanamicro.com>,
	Isaku Yamahata <isaku.yamahata@...el.com>, Erdem Aktas
	<erdemaktas@...gle.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, "Roger
 Wang" <runanwang@...gle.com>, Binbin Wu <binbin.wu@...ux.intel.com>, "Oliver
 Upton" <oliver.upton@...ux.dev>, "Pratik R. Sampat"
	<pratikrajesh.sampat@....com>, Reinette Chatre <reinette.chatre@...el.com>,
	Ira Weiny <ira.weiny@...el.com>, Chao Gao <chao.gao@...el.com>, Chenyi Qiang
	<chenyi.qiang@...el.com>
CC: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
Subject: Re: [PATCH v12 12/23] KVM: selftests: Add helper to initialize TDX VM

Sagi Shahar wrote:

[snip]

> diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> index dafdc7e46abe..a2509959c7ce 100644
> --- a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> @@ -11,6 +11,60 @@ static inline bool is_tdx_vm(struct kvm_vm *vm)
>  	return vm->type == KVM_X86_TDX_VM;
>  }
>  
> +/*
> + * TDX ioctls
> + */
> +
> +#define __vm_tdx_vm_ioctl(vm, cmd, metadata, arg)			\

NIT: Why not call 'metadata' -> 'flags'?

> +({									\
> +	int r;								\
> +									\
> +	union {								\
> +		struct kvm_tdx_cmd c;					\
> +		unsigned long raw;					\
> +	} tdx_cmd = { .c = {						\
> +		.id = (cmd),						\
> +		.flags = (uint32_t)(metadata),				\
> +		.data = (uint64_t)(arg),				\
> +	} };								\
> +									\
> +	r = __vm_ioctl(vm, KVM_MEMORY_ENCRYPT_OP, &tdx_cmd.raw);	\
> +	r ?: tdx_cmd.c.hw_error;					\
> +})

I see this is a common pattern for kvm selftests but I'm struggling to
figure out why this is a macro and not a function call?

> +
> +#define vm_tdx_vm_ioctl(vm, cmd, flags, arg)				\
> +({									\
> +	int ret = __vm_tdx_vm_ioctl(vm, cmd, flags, arg);		\
> +									\
> +	__TEST_ASSERT_VM_VCPU_IOCTL(!ret, #cmd,	ret, vm);		\
> +})
> +
> +#define __vm_tdx_vcpu_ioctl(vcpu, cmd, metadata, arg)			\

NIT: Why not just call 'metadata', 'flags'?

> +({									\
> +	int r;								\
> +									\
> +	union {								\
> +		struct kvm_tdx_cmd c;					\
> +		unsigned long raw;					\
> +	} tdx_cmd = { .c = {						\
> +		.id = (cmd),						\
> +		.flags = (uint32_t)(metadata),				\
> +		.data = (uint64_t)(arg),				\
> +	} };								\
> +									\
> +	r = __vcpu_ioctl(vcpu, KVM_MEMORY_ENCRYPT_OP, &tdx_cmd.raw);	\
> +	r ?: tdx_cmd.c.hw_error;					\
> +})
> +

[snip]

> +
> +static struct kvm_tdx_capabilities *tdx_read_capabilities(struct kvm_vm *vm)
> +{
> +	struct kvm_tdx_capabilities *tdx_cap = NULL;
> +	int nr_cpuid_configs = 4;
> +	int rc = -1;
> +	int i;
> +
> +	do {
> +		nr_cpuid_configs *= 2;
> +
> +		tdx_cap = realloc(tdx_cap, sizeof(*tdx_cap) +
> +					   sizeof(tdx_cap->cpuid) +
> +					   (sizeof(struct kvm_cpuid_entry2) * nr_cpuid_configs));
> +		TEST_ASSERT(tdx_cap,
> +			    "Could not allocate memory for tdx capability nr_cpuid_configs %d\n",
> +			    nr_cpuid_configs);
> +
> +		tdx_cap->cpuid.nent = nr_cpuid_configs;
> +		rc = __vm_tdx_vm_ioctl(vm, KVM_TDX_CAPABILITIES, 0, tdx_cap);

Why not use vm_tdx_vm_ioctl()?

Generally though it is good.

Reviewed-by: Ira Weiny <ira.weiny@...el.com>

[snip]