kvm: selftests: create a GDT and TSS

The GDT and the TSS base were left to zero, and this has interesting effects
when the TSS descriptor is later read to set up a VMCS's TR_BASE.  Basically
it worked by chance, and this patch fixes it by setting up all the protected
mode data structures properly.

Because the GDT and TSS addresses are virtual, the page tables now always
exist at the time of vcpu setup.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 70 insertions, 41 deletions

diff --git a/tools/testing/selftests/kvm/lib/x86.c b/tools/testing/selftests/kvm/lib/x86.c
index 2f17675f4275..024e95f1b470 100644
--- a/tools/testing/selftests/kvm/lib/x86.c
+++ b/tools/testing/selftests/kvm/lib/x86.c
@@ -239,25 +239,6 @@ void virt_pgd_alloc(struct kvm_vm *vm, uint32_t pgd_memslot)
 		vm_paddr_t paddr = vm_phy_page_alloc(vm,
 			KVM_GUEST_PAGE_TABLE_MIN_PADDR, pgd_memslot);
 		vm->pgd = paddr;
-
-		/* Set pointer to pgd tables in all the VCPUs that
-		 * have already been created.  Future VCPUs will have
-		 * the value set as each one is created.
-		 */
-		for (struct vcpu *vcpu = vm->vcpu_head; vcpu;
-			vcpu = vcpu->next) {
-			struct kvm_sregs sregs;
-
-			/* Obtain the current system register settings */
-			vcpu_sregs_get(vm, vcpu->id, &sregs);
-
-			/* Set and store the pointer to the start of the
-			 * pgd tables.
-			 */
-			sregs.cr3 = vm->pgd;
-			vcpu_sregs_set(vm, vcpu->id, &sregs);
-		}
-
 		vm->pgd_created = true;
 	}
 }
@@ -460,9 +441,32 @@ static void kvm_seg_set_unusable(struct kvm_segment *segp)
 	segp->unusable = true;
 }
 
+static void kvm_seg_fill_gdt_64bit(struct kvm_vm *vm, struct kvm_segment *segp)
+{
+	void *gdt = addr_gva2hva(vm, vm->gdt);
+	struct desc64 *desc = gdt + (segp->selector >> 3) * 8;
+
+	desc->limit0 = segp->limit & 0xFFFF;
+	desc->base0 = segp->base & 0xFFFF;
+	desc->base1 = segp->base >> 16;
+	desc->s = segp->s;
+	desc->type = segp->type;
+	desc->dpl = segp->dpl;
+	desc->p = segp->present;
+	desc->limit1 = segp->limit >> 16;
+	desc->l = segp->l;
+	desc->db = segp->db;
+	desc->g = segp->g;
+	desc->base2 = segp->base >> 24;
+	if (!segp->s)
+		desc->base3 = segp->base >> 32;
+}
+
+
 /* Set Long Mode Flat Kernel Code Segment
  *
  * Input Args:
+ *   vm - VM whose GDT is being filled, or NULL to only write segp
  *   selector - selector value
  *
  * Output Args:
@@ -473,7 +477,7 @@ static void kvm_seg_set_unusable(struct kvm_segment *segp)
  * Sets up the KVM segment pointed to by segp, to be a code segment
  * with the selector value given by selector.
  */
-static void kvm_seg_set_kernel_code_64bit(uint16_t selector,
+static void kvm_seg_set_kernel_code_64bit(struct kvm_vm *vm, uint16_t selector,
 	struct kvm_segment *segp)
 {
 	memset(segp, 0, sizeof(*segp));
@@ -486,11 +490,14 @@ static void kvm_seg_set_kernel_code_64bit(uint16_t selector,
 	segp->g = true;
 	segp->l = true;
 	segp->present = 1;
+	if (vm)
+		kvm_seg_fill_gdt_64bit(vm, segp);
 }
 
 /* Set Long Mode Flat Kernel Data Segment
  *
  * Input Args:
+ *   vm - VM whose GDT is being filled, or NULL to only write segp
  *   selector - selector value
  *
  * Output Args:
@@ -501,7 +508,7 @@ static void kvm_seg_set_kernel_code_64bit(uint16_t selector,
  * Sets up the KVM segment pointed to by segp, to be a data segment
  * with the selector value given by selector.
  */
-static void kvm_seg_set_kernel_data_64bit(uint16_t selector,
+static void kvm_seg_set_kernel_data_64bit(struct kvm_vm *vm, uint16_t selector,
 	struct kvm_segment *segp)
 {
 	memset(segp, 0, sizeof(*segp));
@@ -513,6 +520,8 @@ static void kvm_seg_set_kernel_data_64bit(uint16_t selector,
 					  */
 	segp->g = true;
 	segp->present = true;
+	if (vm)
+		kvm_seg_fill_gdt_64bit(vm, segp);
 }
 
 /* Address Guest Virtual to Guest Physical
@@ -575,13 +584,45 @@ unmapped_gva:
 		    "gva: 0x%lx", gva);
 }
 
-void vcpu_setup(struct kvm_vm *vm, int vcpuid)
+static void kvm_setup_gdt(struct kvm_vm *vm, struct kvm_dtable *dt, int gdt_memslot,
+			  int pgd_memslot)
+{
+	if (!vm->gdt)
+		vm->gdt = vm_vaddr_alloc(vm, getpagesize(),
+			KVM_UTIL_MIN_VADDR, gdt_memslot, pgd_memslot);
+
+	dt->base = vm->gdt;
+	dt->limit = getpagesize();
+}
+
+static void kvm_setup_tss_64bit(struct kvm_vm *vm, struct kvm_segment *segp,
+				int selector, int gdt_memslot,
+				int pgd_memslot)
+{
+	if (!vm->tss)
+		vm->tss = vm_vaddr_alloc(vm, getpagesize(),
+			KVM_UTIL_MIN_VADDR, gdt_memslot, pgd_memslot);
+
+	memset(segp, 0, sizeof(*segp));
+	segp->base = vm->tss;
+	segp->limit = 0x67;
+	segp->selector = selector;
+	segp->type = 0xb;
+	segp->present = 1;
+	kvm_seg_fill_gdt_64bit(vm, segp);
+}
+
+void vcpu_setup(struct kvm_vm *vm, int vcpuid, int pgd_memslot, int gdt_memslot)
 {
 	struct kvm_sregs sregs;
 
 	/* Set mode specific system register values. */
 	vcpu_sregs_get(vm, vcpuid, &sregs);
 
+	sregs.idt.limit = 0;
+
+	kvm_setup_gdt(vm, &sregs.gdt, gdt_memslot, pgd_memslot);
+
 	switch (vm->mode) {
 	case VM_MODE_FLAT48PG:
 		sregs.cr0 = X86_CR0_PE | X86_CR0_NE | X86_CR0_PG;
@@ -589,30 +630,18 @@ void vcpu_setup(struct kvm_vm *vm, int vcpuid)
 		sregs.efer |= (EFER_LME | EFER_LMA | EFER_NX);
 
 		kvm_seg_set_unusable(&sregs.ldt);
-		kvm_seg_set_kernel_code_64bit(0x8, &sregs.cs);
-		kvm_seg_set_kernel_data_64bit(0x10, &sregs.ds);
-		kvm_seg_set_kernel_data_64bit(0x10, &sregs.es);
+		kvm_seg_set_kernel_code_64bit(vm, 0x8, &sregs.cs);
+		kvm_seg_set_kernel_data_64bit(vm, 0x10, &sregs.ds);
+		kvm_seg_set_kernel_data_64bit(vm, 0x10, &sregs.es);
+		kvm_setup_tss_64bit(vm, &sregs.tr, 0x18, gdt_memslot, pgd_memslot);
 		break;
 
 	default:
 		TEST_ASSERT(false, "Unknown guest mode, mode: 0x%x", vm->mode);
 	}
-	vcpu_sregs_set(vm, vcpuid, &sregs);
-
-	/* If virtual translation table have been setup, set system register
-	 * to point to the tables.  It's okay if they haven't been setup yet,
-	 * in that the code that sets up the virtual translation tables, will
-	 * go back through any VCPUs that have already been created and set
-	 * their values.
-	 */
-	if (vm->pgd_created) {
-		struct kvm_sregs sregs;
 
-		vcpu_sregs_get(vm, vcpuid, &sregs);
-
-		sregs.cr3 = vm->pgd;
-		vcpu_sregs_set(vm, vcpuid, &sregs);
-	}
+	sregs.cr3 = vm->pgd;
+	vcpu_sregs_set(vm, vcpuid, &sregs);
 }
 /* Adds a vCPU with reasonable defaults (i.e., a stack)
  *
@@ -629,7 +658,7 @@ void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code)
 				     DEFAULT_GUEST_STACK_VADDR_MIN, 0, 0);
 
 	/* Create VCPU */
-	vm_vcpu_add(vm, vcpuid);
+	vm_vcpu_add(vm, vcpuid, 0, 0);
 
 	/* Setup guest general purpose registers */
 	vcpu_regs_get(vm, vcpuid, &regs);