KVM: selftests: Fold x86's descriptor tables helpers into vcpu_init_sregs()

Now that the per-VM, on-demand allocation logic in kvm_setup_gdt() and
vcpu_init_descriptor_tables() is gone, fold them into vcpu_init_sregs().

Note, both kvm_setup_gdt() and vcpu_init_descriptor_tables() configured the
GDT, which is why it looks like kvm_setup_gdt() disappears.

Opportunistically delete the pointless zeroing of the IDT limit (it was
being unconditionally overwritten by vcpu_init_descriptor_tables()).

Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Link: https://lore.kernel.org/r/20240314232637.2538648-15-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

tools/testing/selftests/kvm/lib/x86_64/processor.c

@@ -517,12 +517,6 @@ vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
 	return vm_untag_gpa(vm, PTE_GET_PA(*pte)) | (gva & ~HUGEPAGE_MASK(level));
 }
 
-static void kvm_setup_gdt(struct kvm_vm *vm, struct kvm_dtable *dt)
-{
-	dt->base = vm->arch.gdt;
-	dt->limit = getpagesize() - 1;
-}
-
 static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
 				int selector)
 {
@@ -538,20 +532,6 @@ static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
 	kvm_seg_fill_gdt_64bit(vm, segp);
 }
 
-static void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu)
-{
-	struct kvm_vm *vm = vcpu->vm;
-	struct kvm_sregs sregs;
-
-	vcpu_sregs_get(vcpu, &sregs);
-	sregs.idt.base = vm->arch.idt;
-	sregs.idt.limit = NUM_INTERRUPTS * sizeof(struct idt_entry) - 1;
-	sregs.gdt.base = vm->arch.gdt;
-	sregs.gdt.limit = getpagesize() - 1;
-	kvm_seg_set_kernel_data_64bit(NULL, DEFAULT_DATA_SELECTOR, &sregs.gs);
-	vcpu_sregs_set(vcpu, &sregs);
-}
-
 static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
 {
 	struct kvm_sregs sregs;
@@ -561,9 +541,10 @@ static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
 	/* Set mode specific system register values. */
 	vcpu_sregs_get(vcpu, &sregs);
 
-	sregs.idt.limit = 0;
-
-	kvm_setup_gdt(vm, &sregs.gdt);
+	sregs.idt.base = vm->arch.idt;
+	sregs.idt.limit = NUM_INTERRUPTS * sizeof(struct idt_entry) - 1;
+	sregs.gdt.base = vm->arch.gdt;
+	sregs.gdt.limit = getpagesize() - 1;
 
 	sregs.cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG;
 	sregs.cr4 |= X86_CR4_PAE | X86_CR4_OSFXSR;
@@ -573,12 +554,11 @@ static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
 	kvm_seg_set_kernel_code_64bit(vm, DEFAULT_CODE_SELECTOR, &sregs.cs);
 	kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs.ds);
 	kvm_seg_set_kernel_data_64bit(vm, DEFAULT_DATA_SELECTOR, &sregs.es);
+	kvm_seg_set_kernel_data_64bit(NULL, DEFAULT_DATA_SELECTOR, &sregs.gs);
 	kvm_setup_tss_64bit(vm, &sregs.tr, 0x18);
 
 	sregs.cr3 = vm->pgd;
 	vcpu_sregs_set(vcpu, &sregs);
-
-	vcpu_init_descriptor_tables(vcpu);
 }
 
 static void set_idt_entry(struct kvm_vm *vm, int vector, unsigned long addr,