Re: [PATCH v9 11/19] KVM: selftests: Set up TDX boot parameters region

[Binbin Wu <binbin.wu@linux.intel.com>]

On 8/21/2025 12:29 PM, Sagi Shahar wrote:
> Allocate memory for TDX boot parameters and define the utility functions
> necessary to fill this memory with the boot parameters.
>
> Co-developed-by: Ackerley Tng <ackerleytng@google.com>
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>
> Signed-off-by: Sagi Shahar <sagis@google.com>
> ---
>   .../selftests/kvm/include/x86/tdx/tdx_util.h  |  4 +
>   .../selftests/kvm/lib/x86/tdx/tdx_util.c      | 73 +++++++++++++++++++
>   2 files changed, 77 insertions(+)
>
> 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 ec05bcd59145..dafdc7e46abe 100644
> --- a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> @@ -12,5 +12,9 @@ static inline bool is_tdx_vm(struct kvm_vm *vm)
>   }
>   
>   void vm_tdx_setup_boot_code_region(struct kvm_vm *vm);
> +void vm_tdx_setup_boot_parameters_region(struct kvm_vm *vm, uint32_t nr_runnable_vcpus);
> +void vm_tdx_load_common_boot_parameters(struct kvm_vm *vm);
> +void vm_tdx_load_vcpu_boot_parameters(struct kvm_vm *vm, struct kvm_vcpu *vcpu);
> +void vm_tdx_set_vcpu_entry_point(struct kvm_vcpu *vcpu, void *guest_code);
>   
>   #endif // SELFTESTS_TDX_TDX_UTIL_H
> 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 15833b9eb5d5..52dc25e0cce4 100644
> --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> @@ -5,10 +5,12 @@
>   #include "kvm_util.h"
>   #include "processor.h"
>   #include "tdx/td_boot.h"
> +#include "tdx/td_boot_asm.h"
>   #include "tdx/tdx_util.h"
>   
>   /* Arbitrarily selected to avoid overlaps with anything else */
>   #define TD_BOOT_CODE_SLOT	20
> +#define TD_BOOT_PARAMETERS_SLOT	21
>   
>   #define X86_RESET_VECTOR	0xfffffff0ul
>   #define X86_RESET_VECTOR_SIZE	16
> @@ -52,3 +54,74 @@ void vm_tdx_setup_boot_code_region(struct kvm_vm *vm)
>   	hva[1] = 256 - 2 - TD_BOOT_CODE_SIZE;
>   	hva[2] = 0xcc;
>   }
> +
> +void vm_tdx_setup_boot_parameters_region(struct kvm_vm *vm, uint32_t nr_runnable_vcpus)
> +{
> +	size_t boot_params_size =
> +		sizeof(struct td_boot_parameters) +
> +		nr_runnable_vcpus * sizeof(struct td_per_vcpu_parameters);
> +	int npages = DIV_ROUND_UP(boot_params_size, PAGE_SIZE);
> +	vm_paddr_t gpa;
> +
> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
> +				    TD_BOOT_PARAMETERS_GPA,
> +				    TD_BOOT_PARAMETERS_SLOT, npages,
> +				    KVM_MEM_GUEST_MEMFD);
> +	gpa = vm_phy_pages_alloc(vm, npages, TD_BOOT_PARAMETERS_GPA, TD_BOOT_PARAMETERS_SLOT);
> +	TEST_ASSERT(gpa == TD_BOOT_PARAMETERS_GPA, "Failed vm_phy_pages_alloc\n");
> +
> +	virt_map(vm, TD_BOOT_PARAMETERS_GPA, TD_BOOT_PARAMETERS_GPA, npages);
> +}
> +
> +void vm_tdx_load_common_boot_parameters(struct kvm_vm *vm)
> +{
> +	struct td_boot_parameters *params =
> +		addr_gpa2hva(vm, TD_BOOT_PARAMETERS_GPA);
> +	uint32_t cr4;
> +
> +	TEST_ASSERT_EQ(vm->mode, VM_MODE_PXXV48_4K);
> +
> +	cr4 = kvm_get_default_cr4();
> +
> +	/* TDX spec 11.6.2: CR4 bit MCE is fixed to 1 */
> +	cr4 |= X86_CR4_MCE;
> +
> +	/* Set this because UEFI also sets this up, to handle XMM exceptions */
> +	cr4 |= X86_CR4_OSXMMEXCPT;
> +
> +	/* TDX spec 11.6.2: CR4 bit VMXE and SMXE are fixed to 0 */
> +	cr4 &= ~(X86_CR4_VMXE | X86_CR4_SMXE);
> +
> +	/* Set parameters! */
> +	params->cr0 = kvm_get_default_cr0();
> +	params->cr3 = vm->pgd;
> +	params->cr4 = cr4;
> +	params->idtr.base = vm->arch.idt;
> +	params->idtr.limit = kvm_get_default_idt_limit();
> +	params->gdtr.base = vm->arch.gdt;
> +	params->gdtr.limit = kvm_get_default_gdt_limit();
> +
> +	TEST_ASSERT(params->cr0 != 0, "cr0 should not be 0");
> +	TEST_ASSERT(params->cr3 != 0, "cr3 should not be 0");
> +	TEST_ASSERT(params->cr4 != 0, "cr4 should not be 0");
> +	TEST_ASSERT(params->gdtr.base != 0, "gdt base address should not be 0");
> +	TEST_ASSERT(params->idtr.base != 0, "idt base address should not be 0");
> +}
> +
> +void vm_tdx_load_vcpu_boot_parameters(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
> +{
> +	struct td_boot_parameters *params =
> +		addr_gpa2hva(vm, TD_BOOT_PARAMETERS_GPA);
> +	struct td_per_vcpu_parameters *vcpu_params =
> +		&params->per_vcpu[vcpu->id];

Nit: Better to align the style on whether wrap or not due to max characters per
line

> +
> +	vcpu_params->esp_gva = kvm_allocate_vcpu_stack(vm);
> +}
> +
> +void vm_tdx_set_vcpu_entry_point(struct kvm_vcpu *vcpu, void *guest_code)
> +{
> +	struct td_boot_parameters *params = addr_gpa2hva(vcpu->vm, TD_BOOT_PARAMETERS_GPA);
> +	struct td_per_vcpu_parameters *vcpu_params = &params->per_vcpu[vcpu->id];
> +
> +	vcpu_params->guest_code = (uint64_t)guest_code;
> +}