KVM: selftests: Init IDT and exception handlers for all VMs/vCPUs on x86

Initialize the IDT and exception handlers for all non-barebones VMs and
vCPUs on x86.  Forcing tests to manually configure the IDT just to save
8KiB of memory is a terrible tradeoff, and also leads to weird tests
(multiple tests have deliberately relied on shutdown to indicate success),
and hard-to-debug failures, e.g. instead of a precise unexpected exception
failure, tests see only shutdown.

Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Link: https://lore.kernel.org/r/20240314232637.2538648-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -1134,8 +1134,6 @@ struct idt_entry {
 	uint32_t offset2; uint32_t reserved;
 };
 
-void vm_init_descriptor_tables(struct kvm_vm *vm);
-void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu);
 void vm_install_exception_handler(struct kvm_vm *vm, int vector,
 			void (*handler)(struct ex_regs *));
 

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

@@ -541,7 +541,7 @@ static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
 	kvm_seg_fill_gdt_64bit(vm, segp);
 }
 
-void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu)
+static void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu)
 {
 	struct kvm_vm *vm = vcpu->vm;
 	struct kvm_sregs sregs;
@@ -586,6 +586,8 @@ static void vcpu_init_sregs(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
 
 	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,
@@ -639,7 +641,7 @@ void route_exception(struct ex_regs *regs)
 		     regs->vector, regs->rip);
 }
 
-void vm_init_descriptor_tables(struct kvm_vm *vm)
+static void vm_init_descriptor_tables(struct kvm_vm *vm)
 {
 	extern void *idt_handlers;
 	int i;
@@ -671,6 +673,8 @@ void assert_on_unhandled_exception(struct kvm_vcpu *vcpu)
 void kvm_arch_vm_post_create(struct kvm_vm *vm)
 {
 	vm_create_irqchip(vm);
+	vm_init_descriptor_tables(vm);
+
 	sync_global_to_guest(vm, host_cpu_is_intel);
 	sync_global_to_guest(vm, host_cpu_is_amd);
 	sync_global_to_guest(vm, is_forced_emulation_enabled);

tools/testing/selftests/kvm/x86_64/amx_test.c

@@ -244,8 +244,6 @@ int main(int argc, char *argv[])
 	vcpu_regs_get(vcpu, &regs1);
 
 	/* Register #NM handler */
-	vm_init_descriptor_tables(vm);
-	vcpu_init_descriptor_tables(vcpu);
 	vm_install_exception_handler(vm, NM_VECTOR, guest_nm_handler);
 
 	/* amx cfg for guest_code */

tools/testing/selftests/kvm/x86_64/fix_hypercall_test.c

@@ -110,8 +110,6 @@ static void test_fix_hypercall(struct kvm_vcpu *vcpu, bool disable_quirk)
 {
 	struct kvm_vm *vm = vcpu->vm;
 
-	vm_init_descriptor_tables(vm);
-	vcpu_init_descriptor_tables(vcpu);
 	vm_install_exception_handler(vcpu->vm, UD_VECTOR, guest_ud_handler);
 
 	if (disable_quirk)

tools/testing/selftests/kvm/x86_64/hyperv_evmcs.c

@@ -257,8 +257,6 @@ int main(int argc, char *argv[])
 	vcpu_args_set(vcpu, 3, vmx_pages_gva, hv_pages_gva, addr_gva2gpa(vm, hcall_page));
 	vcpu_set_msr(vcpu, HV_X64_MSR_VP_INDEX, vcpu->id);
 
-	vm_init_descriptor_tables(vm);
-	vcpu_init_descriptor_tables(vcpu);
 	vm_install_exception_handler(vm, UD_VECTOR, guest_ud_handler);
 	vm_install_exception_handler(vm, NMI_VECTOR, guest_nmi_handler);
 

tools/testing/selftests/kvm/x86_64/hyperv_features.c

@@ -156,9 +156,6 @@ static void guest_test_msrs_access(void)
 			vcpu_init_cpuid(vcpu, prev_cpuid);
 		}
 
-		vm_init_descriptor_tables(vm);
-		vcpu_init_descriptor_tables(vcpu);
-
 		/* TODO: Make this entire test easier to maintain. */
 		if (stage >= 21)
 			vcpu_enable_cap(vcpu, KVM_CAP_HYPERV_SYNIC2, 0);
@@ -532,9 +529,6 @@ static void guest_test_hcalls_access(void)
 	while (true) {
 		vm = vm_create_with_one_vcpu(&vcpu, guest_hcall);
 
-		vm_init_descriptor_tables(vm);
-		vcpu_init_descriptor_tables(vcpu);
-
 		/* Hypercall input/output */
 		hcall_page = vm_vaddr_alloc_pages(vm, 2);
 		memset(addr_gva2hva(vm, hcall_page), 0x0, 2 * getpagesize());

tools/testing/selftests/kvm/x86_64/hyperv_ipi.c

@@ -254,16 +254,13 @@ int main(int argc, char *argv[])
 	hcall_page = vm_vaddr_alloc_pages(vm, 2);
 	memset(addr_gva2hva(vm, hcall_page), 0x0, 2 * getpagesize());
 
-	vm_init_descriptor_tables(vm);
 
 	vcpu[1] = vm_vcpu_add(vm, RECEIVER_VCPU_ID_1, receiver_code);
-	vcpu_init_descriptor_tables(vcpu[1]);
 	vcpu_args_set(vcpu[1], 2, hcall_page, addr_gva2gpa(vm, hcall_page));
 	vcpu_set_msr(vcpu[1], HV_X64_MSR_VP_INDEX, RECEIVER_VCPU_ID_1);
 	vcpu_set_hv_cpuid(vcpu[1]);
 
 	vcpu[2] = vm_vcpu_add(vm, RECEIVER_VCPU_ID_2, receiver_code);
-	vcpu_init_descriptor_tables(vcpu[2]);
 	vcpu_args_set(vcpu[2], 2, hcall_page, addr_gva2gpa(vm, hcall_page));
 	vcpu_set_msr(vcpu[2], HV_X64_MSR_VP_INDEX, RECEIVER_VCPU_ID_2);
 	vcpu_set_hv_cpuid(vcpu[2]);

tools/testing/selftests/kvm/x86_64/kvm_pv_test.c

@@ -183,9 +183,6 @@ int main(void)
 
 	vcpu_clear_cpuid_entry(vcpu, KVM_CPUID_FEATURES);
 
-	vm_init_descriptor_tables(vm);
-	vcpu_init_descriptor_tables(vcpu);
-
 	enter_guest(vcpu);
 	kvm_vm_free(vm);
 

tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c

@@ -80,9 +80,6 @@ int main(int argc, char *argv[])
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
 	vcpu_clear_cpuid_feature(vcpu, X86_FEATURE_MWAIT);
 
-	vm_init_descriptor_tables(vm);
-	vcpu_init_descriptor_tables(vcpu);
-
 	while (1) {
 		vcpu_run(vcpu);
 		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);

tools/testing/selftests/kvm/x86_64/platform_info_test.c

@@ -49,9 +49,6 @@ int main(int argc, char *argv[])
 
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
 
-	vm_init_descriptor_tables(vm);
-	vcpu_init_descriptor_tables(vcpu);
-
 	msr_platform_info = vcpu_get_msr(vcpu, MSR_PLATFORM_INFO);
 	vcpu_set_msr(vcpu, MSR_PLATFORM_INFO,
 		     msr_platform_info | MSR_PLATFORM_INFO_MAX_TURBO_RATIO);