1 files changed, 409 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 63afca1c295..32d910044f8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -18,6 +18,7 @@
 #include "irq.h"
 #include "mmu.h"
 #include "i8254.h"
+#include "tss.h"
 
 #include <linux/clocksource.h>
 #include <linux/kvm.h>
@@ -3077,6 +3078,414 @@ static void set_segment(struct kvm_vcpu *vcpu,
 	kvm_x86_ops->set_segment(vcpu, var, seg);
 }
 
+static void seg_desct_to_kvm_desct(struct desc_struct *seg_desc, u16 selector,
+				   struct kvm_segment *kvm_desct)
+{
+	kvm_desct->base = seg_desc->base0;
+	kvm_desct->base |= seg_desc->base1 << 16;
+	kvm_desct->base |= seg_desc->base2 << 24;
+	kvm_desct->limit = seg_desc->limit0;
+	kvm_desct->limit |= seg_desc->limit << 16;
+	kvm_desct->selector = selector;
+	kvm_desct->type = seg_desc->type;
+	kvm_desct->present = seg_desc->p;
+	kvm_desct->dpl = seg_desc->dpl;
+	kvm_desct->db = seg_desc->d;
+	kvm_desct->s = seg_desc->s;
+	kvm_desct->l = seg_desc->l;
+	kvm_desct->g = seg_desc->g;
+	kvm_desct->avl = seg_desc->avl;
+	if (!selector)
+		kvm_desct->unusable = 1;
+	else
+		kvm_desct->unusable = 0;
+	kvm_desct->padding = 0;
+}
+
+static void get_segment_descritptor_dtable(struct kvm_vcpu *vcpu,
+					   u16 selector,
+					   struct descriptor_table *dtable)
+{
+	if (selector & 1 << 2) {
+		struct kvm_segment kvm_seg;
+
+		get_segment(vcpu, &kvm_seg, VCPU_SREG_LDTR);
+
+		if (kvm_seg.unusable)
+			dtable->limit = 0;
+		else
+			dtable->limit = kvm_seg.limit;
+		dtable->base = kvm_seg.base;
+	}
+	else
+		kvm_x86_ops->get_gdt(vcpu, dtable);
+}
+
+/* allowed just for 8 bytes segments */
+static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
+					 struct desc_struct *seg_desc)
+{
+	struct descriptor_table dtable;
+	u16 index = selector >> 3;
+
+	get_segment_descritptor_dtable(vcpu, selector, &dtable);
+
+	if (dtable.limit < index * 8 + 7) {
+		kvm_queue_exception_e(vcpu, GP_VECTOR, selector & 0xfffc);
+		return 1;
+	}
+	return kvm_read_guest(vcpu->kvm, dtable.base + index * 8, seg_desc, 8);
+}
+
+/* allowed just for 8 bytes segments */
+static int save_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
+					 struct desc_struct *seg_desc)
+{
+	struct descriptor_table dtable;
+	u16 index = selector >> 3;
+
+	get_segment_descritptor_dtable(vcpu, selector, &dtable);
+
+	if (dtable.limit < index * 8 + 7)
+		return 1;
+	return kvm_write_guest(vcpu->kvm, dtable.base + index * 8, seg_desc, 8);
+}
+
+static u32 get_tss_base_addr(struct kvm_vcpu *vcpu,
+			     struct desc_struct *seg_desc)
+{
+	u32 base_addr;
+
+	base_addr = seg_desc->base0;
+	base_addr |= (seg_desc->base1 << 16);
+	base_addr |= (seg_desc->base2 << 24);
+
+	return base_addr;
+}
+
+static int load_tss_segment32(struct kvm_vcpu *vcpu,
+			      struct desc_struct *seg_desc,
+			      struct tss_segment_32 *tss)
+{
+	u32 base_addr;
+
+	base_addr = get_tss_base_addr(vcpu, seg_desc);
+
+	return kvm_read_guest(vcpu->kvm, base_addr, tss,
+			      sizeof(struct tss_segment_32));
+}
+
+static int save_tss_segment32(struct kvm_vcpu *vcpu,
+			      struct desc_struct *seg_desc,
+			      struct tss_segment_32 *tss)
+{
+	u32 base_addr;
+
+	base_addr = get_tss_base_addr(vcpu, seg_desc);
+
+	return kvm_write_guest(vcpu->kvm, base_addr, tss,
+			       sizeof(struct tss_segment_32));
+}
+
+static int load_tss_segment16(struct kvm_vcpu *vcpu,
+			      struct desc_struct *seg_desc,
+			      struct tss_segment_16 *tss)
+{
+	u32 base_addr;
+
+	base_addr = get_tss_base_addr(vcpu, seg_desc);
+
+	return kvm_read_guest(vcpu->kvm, base_addr, tss,
+			      sizeof(struct tss_segment_16));
+}
+
+static int save_tss_segment16(struct kvm_vcpu *vcpu,
+			      struct desc_struct *seg_desc,
+			      struct tss_segment_16 *tss)
+{
+	u32 base_addr;
+
+	base_addr = get_tss_base_addr(vcpu, seg_desc);
+
+	return kvm_write_guest(vcpu->kvm, base_addr, tss,
+			       sizeof(struct tss_segment_16));
+}
+
+static u16 get_segment_selector(struct kvm_vcpu *vcpu, int seg)
+{
+	struct kvm_segment kvm_seg;
+
+	get_segment(vcpu, &kvm_seg, seg);
+	return kvm_seg.selector;
+}
+
+static int load_segment_descriptor_to_kvm_desct(struct kvm_vcpu *vcpu,
+						u16 selector,
+						struct kvm_segment *kvm_seg)
+{
+	struct desc_struct seg_desc;
+
+	if (load_guest_segment_descriptor(vcpu, selector, &seg_desc))
+		return 1;
+	seg_desct_to_kvm_desct(&seg_desc, selector, kvm_seg);
+	return 0;
+}
+
+static int load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
+				   int type_bits, int seg)
+{
+	struct kvm_segment kvm_seg;
+
+	if (load_segment_descriptor_to_kvm_desct(vcpu, selector, &kvm_seg))
+		return 1;
+	kvm_seg.type |= type_bits;
+
+	if (seg != VCPU_SREG_SS && seg != VCPU_SREG_CS &&
+	    seg != VCPU_SREG_LDTR)
+		if (!kvm_seg.s)
+			kvm_seg.unusable = 1;
+
+	set_segment(vcpu, &kvm_seg, seg);
+	return 0;
+}
+
+static void save_state_to_tss32(struct kvm_vcpu *vcpu,
+				struct tss_segment_32 *tss)
+{
+	tss->cr3 = vcpu->arch.cr3;
+	tss->eip = vcpu->arch.rip;
+	tss->eflags = kvm_x86_ops->get_rflags(vcpu);
+	tss->eax = vcpu->arch.regs[VCPU_REGS_RAX];
+	tss->ecx = vcpu->arch.regs[VCPU_REGS_RCX];
+	tss->edx = vcpu->arch.regs[VCPU_REGS_RDX];
+	tss->ebx = vcpu->arch.regs[VCPU_REGS_RBX];
+	tss->esp = vcpu->arch.regs[VCPU_REGS_RSP];
+	tss->ebp = vcpu->arch.regs[VCPU_REGS_RBP];
+	tss->esi = vcpu->arch.regs[VCPU_REGS_RSI];
+	tss->edi = vcpu->arch.regs[VCPU_REGS_RDI];
+
+	tss->es = get_segment_selector(vcpu, VCPU_SREG_ES);
+	tss->cs = get_segment_selector(vcpu, VCPU_SREG_CS);
+	tss->ss = get_segment_selector(vcpu, VCPU_SREG_SS);
+	tss->ds = get_segment_selector(vcpu, VCPU_SREG_DS);
+	tss->fs = get_segment_selector(vcpu, VCPU_SREG_FS);
+	tss->gs = get_segment_selector(vcpu, VCPU_SREG_GS);
+	tss->ldt_selector = get_segment_selector(vcpu, VCPU_SREG_LDTR);
+	tss->prev_task_link = get_segment_selector(vcpu, VCPU_SREG_TR);
+}
+
+static int load_state_from_tss32(struct kvm_vcpu *vcpu,
+				  struct tss_segment_32 *tss)
+{
+	kvm_set_cr3(vcpu, tss->cr3);
+
+	vcpu->arch.rip = tss->eip;
+	kvm_x86_ops->set_rflags(vcpu, tss->eflags | 2);
+
+	vcpu->arch.regs[VCPU_REGS_RAX] = tss->eax;
+	vcpu->arch.regs[VCPU_REGS_RCX] = tss->ecx;
+	vcpu->arch.regs[VCPU_REGS_RDX] = tss->edx;
+	vcpu->arch.regs[VCPU_REGS_RBX] = tss->ebx;
+	vcpu->arch.regs[VCPU_REGS_RSP] = tss->esp;
+	vcpu->arch.regs[VCPU_REGS_RBP] = tss->ebp;
+	vcpu->arch.regs[VCPU_REGS_RSI] = tss->esi;
+	vcpu->arch.regs[VCPU_REGS_RDI] = tss->edi;
+
+	if (load_segment_descriptor(vcpu, tss->ldt_selector, 0, VCPU_SREG_LDTR))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->es, 1, VCPU_SREG_ES))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->cs, 9, VCPU_SREG_CS))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->ss, 1, VCPU_SREG_SS))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->ds, 1, VCPU_SREG_DS))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->fs, 1, VCPU_SREG_FS))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->gs, 1, VCPU_SREG_GS))
+		return 1;
+	return 0;
+}
+
+static void save_state_to_tss16(struct kvm_vcpu *vcpu,
+				struct tss_segment_16 *tss)
+{
+	tss->ip = vcpu->arch.rip;
+	tss->flag = kvm_x86_ops->get_rflags(vcpu);
+	tss->ax = vcpu->arch.regs[VCPU_REGS_RAX];
+	tss->cx = vcpu->arch.regs[VCPU_REGS_RCX];
+	tss->dx = vcpu->arch.regs[VCPU_REGS_RDX];
+	tss->bx = vcpu->arch.regs[VCPU_REGS_RBX];
+	tss->sp = vcpu->arch.regs[VCPU_REGS_RSP];
+	tss->bp = vcpu->arch.regs[VCPU_REGS_RBP];
+	tss->si = vcpu->arch.regs[VCPU_REGS_RSI];
+	tss->di = vcpu->arch.regs[VCPU_REGS_RDI];
+
+	tss->es = get_segment_selector(vcpu, VCPU_SREG_ES);
+	tss->cs = get_segment_selector(vcpu, VCPU_SREG_CS);
+	tss->ss = get_segment_selector(vcpu, VCPU_SREG_SS);
+	tss->ds = get_segment_selector(vcpu, VCPU_SREG_DS);
+	tss->ldt = get_segment_selector(vcpu, VCPU_SREG_LDTR);
+	tss->prev_task_link = get_segment_selector(vcpu, VCPU_SREG_TR);
+}
+
+static int load_state_from_tss16(struct kvm_vcpu *vcpu,
+				 struct tss_segment_16 *tss)
+{
+	vcpu->arch.rip = tss->ip;
+	kvm_x86_ops->set_rflags(vcpu, tss->flag | 2);
+	vcpu->arch.regs[VCPU_REGS_RAX] = tss->ax;
+	vcpu->arch.regs[VCPU_REGS_RCX] = tss->cx;
+	vcpu->arch.regs[VCPU_REGS_RDX] = tss->dx;
+	vcpu->arch.regs[VCPU_REGS_RBX] = tss->bx;
+	vcpu->arch.regs[VCPU_REGS_RSP] = tss->sp;
+	vcpu->arch.regs[VCPU_REGS_RBP] = tss->bp;
+	vcpu->arch.regs[VCPU_REGS_RSI] = tss->si;
+	vcpu->arch.regs[VCPU_REGS_RDI] = tss->di;
+
+	if (load_segment_descriptor(vcpu, tss->ldt, 0, VCPU_SREG_LDTR))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->es, 1, VCPU_SREG_ES))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->cs, 9, VCPU_SREG_CS))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->ss, 1, VCPU_SREG_SS))
+		return 1;
+
+	if (load_segment_descriptor(vcpu, tss->ds, 1, VCPU_SREG_DS))
+		return 1;
+	return 0;
+}
+
+int kvm_task_switch_16(struct kvm_vcpu *vcpu, u16 tss_selector,
+		       struct desc_struct *cseg_desc,
+		       struct desc_struct *nseg_desc)
+{
+	struct tss_segment_16 tss_segment_16;
+	int ret = 0;
+
+	if (load_tss_segment16(vcpu, cseg_desc, &tss_segment_16))
+		goto out;
+
+	save_state_to_tss16(vcpu, &tss_segment_16);
+	save_tss_segment16(vcpu, cseg_desc, &tss_segment_16);
+
+	if (load_tss_segment16(vcpu, nseg_desc, &tss_segment_16))
+		goto out;
+	if (load_state_from_tss16(vcpu, &tss_segment_16))
+		goto out;
+
+	ret = 1;
+out:
+	return ret;
+}
+
+int kvm_task_switch_32(struct kvm_vcpu *vcpu, u16 tss_selector,
+		       struct desc_struct *cseg_desc,
+		       struct desc_struct *nseg_desc)
+{
+	struct tss_segment_32 tss_segment_32;
+	int ret = 0;
+
+	if (load_tss_segment32(vcpu, cseg_desc, &tss_segment_32))
+		goto out;
+
+	save_state_to_tss32(vcpu, &tss_segment_32);
+	save_tss_segment32(vcpu, cseg_desc, &tss_segment_32);
+
+	if (load_tss_segment32(vcpu, nseg_desc, &tss_segment_32))
+		goto out;
+	if (load_state_from_tss32(vcpu, &tss_segment_32))
+		goto out;
+
+	ret = 1;
+out:
+	return ret;
+}
+
+int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason)
+{
+	struct kvm_segment tr_seg;
+	struct desc_struct cseg_desc;
+	struct desc_struct nseg_desc;
+	int ret = 0;
+
+	get_segment(vcpu, &tr_seg, VCPU_SREG_TR);
+
+	if (load_guest_segment_descriptor(vcpu, tss_selector, &nseg_desc))
+		goto out;
+
+	if (load_guest_segment_descriptor(vcpu, tr_seg.selector, &cseg_desc))
+		goto out;
+
+
+	if (reason != TASK_SWITCH_IRET) {
+		int cpl;
+
+		cpl = kvm_x86_ops->get_cpl(vcpu);
+		if ((tss_selector & 3) > nseg_desc.dpl || cpl > nseg_desc.dpl) {
+			kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
+			return 1;
+		}
+	}
+
+	if (!nseg_desc.p || (nseg_desc.limit0 | nseg_desc.limit << 16) < 0x67) {
+		kvm_queue_exception_e(vcpu, TS_VECTOR, tss_selector & 0xfffc);
+		return 1;
+	}
+
+	if (reason == TASK_SWITCH_IRET || reason == TASK_SWITCH_JMP) {
+		cseg_desc.type &= ~(1 << 8); //clear the B flag
+		save_guest_segment_descriptor(vcpu, tr_seg.selector,
+					      &cseg_desc);
+	}
+
+	if (reason == TASK_SWITCH_IRET) {
+		u32 eflags = kvm_x86_ops->get_rflags(vcpu);
+		kvm_x86_ops->set_rflags(vcpu, eflags & ~X86_EFLAGS_NT);
+	}
+
+	kvm_x86_ops->skip_emulated_instruction(vcpu);
+	kvm_x86_ops->cache_regs(vcpu);
+
+	if (nseg_desc.type & 8)
+		ret = kvm_task_switch_32(vcpu, tss_selector, &cseg_desc,
+					 &nseg_desc);
+	else
+		ret = kvm_task_switch_16(vcpu, tss_selector, &cseg_desc,
+					 &nseg_desc);
+
+	if (reason == TASK_SWITCH_CALL || reason == TASK_SWITCH_GATE) {
+		u32 eflags = kvm_x86_ops->get_rflags(vcpu);
+		kvm_x86_ops->set_rflags(vcpu, eflags | X86_EFLAGS_NT);
+	}
+
+	if (reason != TASK_SWITCH_IRET) {
+		nseg_desc.type |= (1 << 8);
+		save_guest_segment_descriptor(vcpu, tss_selector,
+					      &nseg_desc);
+	}
+
+	kvm_x86_ops->set_cr0(vcpu, vcpu->arch.cr0 | X86_CR0_TS);
+	seg_desct_to_kvm_desct(&nseg_desc, tss_selector, &tr_seg);
+	tr_seg.type = 11;
+	set_segment(vcpu, &tr_seg, VCPU_SREG_TR);
+out:
+	kvm_x86_ops->decache_regs(vcpu);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kvm_task_switch);
+
 int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
 				  struct kvm_sregs *sregs)
 {