Re: [PATCH v10 10/21] KVM: selftests: Set up TDX boot parameters region

On Mon, Sep 8, 2025 at 3:07 AM Binbin Wu binbin.wu@linux.intel.com wrote:

On 9/4/2025 2:54 PM, Sagi Shahar wrote: [...]

...

+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 */
  

I don't get it. Could you elaborate it a bit?

I'm not entirely sure where this code came from but it looks like this is unnecessary, at least for now. Dropping this in the next version.

...

• 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");
  

+}

[...]