Re: [PATCH v14 10/22] KVM: selftests: Set up TDX boot code region

[Peter Fang <peter.fang@intel.com>]

On Mon, Aug 24, 2026 at 01:00:34PM -0700, Sean Christopherson wrote:
> 
> Ya, looking at this with fresh eyes, AFAICT there's no reason to handcode anything,
> it's just basic arithmetic.
> 
> Side topic, this series doesn't compile for me, so the below isn't even properly
> compile-tested (I hacked in arbitrary literals to get past the undefined references).
> 
> /usr/bin/x86_64-linux-gnu-ld.bfd: tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S:26:(.text+0xf): undefined reference to `TD_BOOT_PARAMETERS_PER_VCPU'
> /usr/bin/x86_64-linux-gnu-ld.bfd: tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S:30:(.text+0x17): undefined reference to `TD_PER_VCPU_PARAMETERS_ESP_GVA'
> /usr/bin/x86_64-linux-gnu-ld.bfd: tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S:33:(.text+0x1d): undefined reference to `TD_BOOT_PARAMETERS_GDT'
> /usr/bin/x86_64-linux-gnu-ld.bfd: tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S:37:(.text+0x26): undefined reference to `TD_BOOT_PARAMETERS_IDT'
> /usr/bin/x86_64-linux-gnu-ld.bfd: tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S:44:(.text+0x2f): undefined reference to `TD_BOOT_PARAMETERS_CR4'
> /usr/bin/x86_64-linux-gnu-ld.bfd: tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S:46:(.text+0x38): undefined reference to `TD_BOOT_PARAMETERS_CR3'
> /usr/bin/x86_64-linux-gnu-ld.bfd: tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S:48:(.text+0x41): undefined reference to `TD_BOOT_PARAMETERS_CR0'
> /usr/bin/x86_64-linux-gnu-ld.bfd: tools/testing/selftests/kvm/lib/x86/tdx/td_boot.S:54:(.text+0x51): undefined reference to `TD_PER_VCPU_PARAMETERS_GUEST_CODE'
> 
> 
> diff --git a/tools/testing/selftests/kvm/include/x86/tdx/td_boot.h b/tools/testing/selftests/kvm/include/x86/tdx/td_boot.h
> index 89cf6c3485be..439d6f10489e 100644
> --- a/tools/testing/selftests/kvm/include/x86/tdx/td_boot.h
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/td_boot.h

Thanks Sean! This diff is pretty much what I had in mind. Just one
comment below...

> diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> index 831b0e5160df..170354dcdb66 100644
> --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> @@ -15,10 +15,11 @@
>  
>  void tdx_vm_setup_boot_code_region(struct kvm_vm *vm)
>  {
> -	size_t total_code_size = TD_BOOT_CODE_SIZE + X86_RESET_VECTOR_SIZE;
> -	gpa_t boot_code_gpa = X86_RESET_VECTOR - TD_BOOT_CODE_SIZE;
> +	const size_t total_size = td_boot_code_end - td_boot;
> +	const size_t boot_code_size = td_boot_reset_vector_trampoline - td_boot;
> +	const gpa_t boot_code_gpa = X86_RESET_VECTOR - boot_code_size;
>  	gpa_t alloc_gpa = round_down(boot_code_gpa, PAGE_SIZE);
> -	size_t nr_pages = DIV_ROUND_UP(total_code_size, PAGE_SIZE);
> +	size_t nr_pages = DIV_ROUND_UP(total_size, PAGE_SIZE);

td_boot_code_end and td_boot could both be non-page-aligned, so instead
this can be:

        size_t nr_pages = (SZ_4G - alloc_gpa) / PAGE_SIZE;

>  	u64 gmem_flags = 0;
>  	gpa_t gpa;
>  	u8 *hva;