Implement emulation of 16/32 bit task switch in emulator.c
Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_emulate.h | 5 +
arch/x86/kvm/emulate.c | 563 ++++++++++++++++++++++++++++++++++++
2 files changed, 568 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index f901467..bd46929 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -11,6 +11,8 @@
#ifndef _ASM_X86_KVM_X86_EMULATE_H
#define _ASM_X86_KVM_X86_EMULATE_H
+#include <asm/desc_defs.h>
+
struct x86_emulate_ctxt;
/*
@@ -210,5 +212,8 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops);
int x86_emulate_insn(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops);
+int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 tss_selector, int reason);
#endif /* _ASM_X86_KVM_X86_EMULATE_H */
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index d696cbd..db4776c 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -33,6 +33,7 @@
#include <asm/kvm_emulate.h>
#include "x86.h"
+#include "tss.h"
/*
* Opcode effective-address decode tables.
@@ -1221,6 +1222,198 @@ done:
return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
}
+static u32 desc_limit_scaled(struct desc_struct *desc)
+{
+ u32 limit = get_desc_limit(desc);
+
+ return desc->g ? (limit << 12) | 0xfff : limit;
+}
+
+static void get_descriptor_table_ptr(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 selector, struct desc_ptr *dt)
+{
+ if (selector & 1 << 2) {
+ struct desc_struct desc;
+ memset (dt, 0, sizeof *dt);
+ if (!ops->get_cached_descriptor(&desc, VCPU_SREG_LDTR, ctxt->vcpu))
+ return;
+
+ dt->size = desc_limit_scaled(&desc); /* what if limit > 65535? */
+ dt->address = get_desc_base(&desc);
+ } else
+ ops->get_gdt(dt, ctxt->vcpu);
+}
+
+/* allowed just for 8 bytes segments */
+static int read_segment_descriptor(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 selector, struct desc_struct *desc)
+{
+ struct desc_ptr dt;
+ u16 index = selector >> 3;
+ int ret;
+ u32 err;
+ ulong addr;
+
+ get_descriptor_table_ptr(ctxt, ops, selector, &dt);
+
+ if (dt.size < index * 8 + 7) {
+ kvm_inject_gp(ctxt->vcpu, selector & 0xfffc);
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+ addr = dt.address + index * 8;
+ ret = ops->read_std(addr, desc, sizeof *desc, ctxt->vcpu, &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT)
+ kvm_inject_page_fault(ctxt->vcpu, addr, err);
+
+ return ret;
+}
+
+/* allowed just for 8 bytes segments */
+static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 selector, struct desc_struct *desc)
+{
+ struct desc_ptr dt;
+ u16 index = selector >> 3;
+ u32 err;
+ ulong addr;
+ int ret;
+
+ get_descriptor_table_ptr(ctxt, ops, selector, &dt);
+
+ if (dt.size < index * 8 + 7) {
+ kvm_inject_gp(ctxt->vcpu, selector & 0xfffc);
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+
+ addr = dt.address + index * 8;
+ ret = ops->write_std(addr, desc, sizeof *desc, ctxt->vcpu, &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT)
+ kvm_inject_page_fault(ctxt->vcpu, addr, err);
+
+ return ret;
+}
+
+static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 selector, int seg)
+{
+ struct desc_struct seg_desc;
+ u8 dpl, rpl, cpl;
+ unsigned err_vec = GP_VECTOR;
+ u32 err_code = 0;
+ bool null_selector = !(selector & ~0x3); /* 0000-0003 are null */
+ int ret;
+
+ memset(&seg_desc, 0, sizeof seg_desc);
+
+ if ((seg <= VCPU_SREG_GS && ctxt->mode == X86EMUL_MODE_VM86)
+ || ctxt->mode == X86EMUL_MODE_REAL) {
+ /* set real mode segment descriptor */
+ set_desc_base(&seg_desc, selector << 4);
+ set_desc_limit(&seg_desc, 0xffff);
+ seg_desc.type = 3;
+ seg_desc.p = 1;
+ seg_desc.s = 1;
+ goto load;
+ }
+
+ /* NULL selector is not valid for TR, CS and SS */
+ if ((seg == VCPU_SREG_CS || seg == VCPU_SREG_SS || seg == VCPU_SREG_TR)
+ && null_selector)
+ goto exception;
+
+ /* TR should be in GDT only */
+ if (seg == VCPU_SREG_TR && (selector & (1 << 2)))
+ goto exception;
+
+ if (null_selector) /* for NULL selector skip all following checks */
+ goto load;
+
+ ret = read_segment_descriptor(ctxt, ops, selector, &seg_desc);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+
+ err_code = selector & 0xfffc;
+ err_vec = GP_VECTOR;
+
+ /* can't load system descriptor into segment selecor */
+ if (seg <= VCPU_SREG_GS && !seg_desc.s)
+ goto exception;
+
+ if (!seg_desc.p) {
+ err_vec = (seg == VCPU_SREG_SS) ? SS_VECTOR : NP_VECTOR;
+ goto exception;
+ }
+
+ rpl = selector & 3;
+ dpl = seg_desc.dpl;
+ cpl = ops->cpl(ctxt->vcpu);
+
+ switch (seg) {
+ case VCPU_SREG_SS:
+ /*
+ * segment is not a writable data segment or segment
+ * selector's RPL != CPL or segment selector's RPL != CPL
+ */
+ if (rpl != cpl || (seg_desc.type & 0xa) != 0x2 || dpl != cpl)
+ goto exception;
+ break;
+ case VCPU_SREG_CS:
+ if (!(seg_desc.type & 8))
+ goto exception;
+
+ if (seg_desc.type & 4) {
+ /* conforming */
+ if (dpl > cpl)
+ goto exception;
+ } else {
+ /* nonconforming */
+ if (rpl > cpl || dpl != cpl)
+ goto exception;
+ }
+ /* CS(RPL) <- CPL */
+ selector = (selector & 0xfffc) | cpl;
+ break;
+ case VCPU_SREG_TR:
+ if (seg_desc.s || (seg_desc.type != 1 && seg_desc.type != 9))
+ goto exception;
+ break;
+ case VCPU_SREG_LDTR:
+ if (seg_desc.s || seg_desc.type != 2)
+ goto exception;
+ break;
+ default: /* DS, ES, FS, or GS */
+ /*
+ * segment is not a data or readable code segment or
+ * ((segment is a data or nonconforming code segment)
+ * and (both RPL and CPL > DPL))
+ */
+ if ((seg_desc.type & 0xa) == 0x8 ||
+ (((seg_desc.type & 0xc) != 0xc) &&
+ (rpl > dpl && cpl > dpl)))
+ goto exception;
+ break;
+ }
+
+ if (seg_desc.s) {
+ /* mark segment as accessed */
+ seg_desc.type |= 1;
+ ret = write_segment_descriptor(ctxt, ops, selector, &seg_desc);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ }
+load:
+ ops->set_segment_selector(selector, seg, ctxt->vcpu);
+ ops->set_cached_descriptor(&seg_desc, seg, ctxt->vcpu);
+ return X86EMUL_CONTINUE;
+exception:
+ kvm_queue_exception_e(ctxt->vcpu, err_vec, err_code);
+ return X86EMUL_PROPAGATE_FAULT;
+}
+
static inline void emulate_push(struct x86_emulate_ctxt *ctxt)
{
struct decode_cache *c = &ctxt->decode;
@@ -1812,6 +2005,376 @@ static bool emulator_io_permited(struct x86_emulate_ctxt *ctxt,
return true;
}
+static u32 get_cached_descriptor_base(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ int seg)
+{
+ struct desc_struct desc;
+ if (ops->get_cached_descriptor(&desc, seg, ctxt->vcpu))
+ return get_desc_base(&desc);
+ else
+ return ~0;
+}
+
+static void save_state_to_tss16(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ struct tss_segment_16 *tss)
+{
+ struct decode_cache *c = &ctxt->decode;
+
+ tss->ip = c->eip;
+ tss->flag = ctxt->eflags;
+ tss->ax = c->regs[VCPU_REGS_RAX];
+ tss->cx = c->regs[VCPU_REGS_RCX];
+ tss->dx = c->regs[VCPU_REGS_RDX];
+ tss->bx = c->regs[VCPU_REGS_RBX];
+ tss->sp = c->regs[VCPU_REGS_RSP];
+ tss->bp = c->regs[VCPU_REGS_RBP];
+ tss->si = c->regs[VCPU_REGS_RSI];
+ tss->di = c->regs[VCPU_REGS_RDI];
+
+ tss->es = ops->get_segment_selector(VCPU_SREG_ES, ctxt->vcpu);
+ tss->cs = ops->get_segment_selector(VCPU_SREG_CS, ctxt->vcpu);
+ tss->ss = ops->get_segment_selector(VCPU_SREG_SS, ctxt->vcpu);
+ tss->ds = ops->get_segment_selector(VCPU_SREG_DS, ctxt->vcpu);
+ tss->ldt = ops->get_segment_selector(VCPU_SREG_LDTR, ctxt->vcpu);
+}
+
+static int load_state_from_tss16(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ struct tss_segment_16 *tss)
+{
+ struct decode_cache *c = &ctxt->decode;
+ int ret;
+
+ c->eip = tss->ip;
+ ctxt->eflags = tss->flag | 2;
+ c->regs[VCPU_REGS_RAX] = tss->ax;
+ c->regs[VCPU_REGS_RCX] = tss->cx;
+ c->regs[VCPU_REGS_RDX] = tss->dx;
+ c->regs[VCPU_REGS_RBX] = tss->bx;
+ c->regs[VCPU_REGS_RSP] = tss->sp;
+ c->regs[VCPU_REGS_RBP] = tss->bp;
+ c->regs[VCPU_REGS_RSI] = tss->si;
+ c->regs[VCPU_REGS_RDI] = tss->di;
+
+ /*
+ * SDM says that segment selectors are loaded before segment
+ * descriptors
+ */
+ ops->set_segment_selector(tss->ldt, VCPU_SREG_LDTR, ctxt->vcpu);
+ ops->set_segment_selector(tss->es, VCPU_SREG_ES, ctxt->vcpu);
+ ops->set_segment_selector(tss->cs, VCPU_SREG_CS, ctxt->vcpu);
+ ops->set_segment_selector(tss->ss, VCPU_SREG_SS, ctxt->vcpu);
+ ops->set_segment_selector(tss->ds, VCPU_SREG_DS, ctxt->vcpu);
+
+ /*
+ * Now load segment descriptors. If fault happenes at this stage
+ * it is handled in a context of new task
+ */
+ ret = load_segment_descriptor(ctxt, ops, tss->ldt, VCPU_SREG_LDTR);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->es, VCPU_SREG_ES);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->cs, VCPU_SREG_CS);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->ss, VCPU_SREG_SS);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->ds, VCPU_SREG_DS);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+
+ return X86EMUL_CONTINUE;
+}
+
+static int task_switch_16(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 tss_selector, u16 old_tss_sel,
+ ulong old_tss_base, struct desc_struct *new_desc)
+{
+ struct tss_segment_16 tss_seg;
+ int ret;
+ u32 err, new_tss_base = get_desc_base(new_desc);
+
+ ret = ops->read_std(old_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+ &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ /* FIXME: need to provide precise fault address */
+ kvm_inject_page_fault(ctxt->vcpu, old_tss_base, err);
+ return ret;
+ }
+
+ save_state_to_tss16(ctxt, ops, &tss_seg);
+
+ ret = ops->write_std(old_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+ &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ /* FIXME: need to provide precise fault address */
+ kvm_inject_page_fault(ctxt->vcpu, old_tss_base, err);
+ return ret;
+ }
+
+ ret = ops->read_std(new_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+ &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ /* FIXME: need to provide precise fault address */
+ kvm_inject_page_fault(ctxt->vcpu, new_tss_base, err);
+ return ret;
+ }
+
+ if (old_tss_sel != 0xffff) {
+ tss_seg.prev_task_link = old_tss_sel;
+
+ ret = ops->write_std(new_tss_base,
+ &tss_seg.prev_task_link,
+ sizeof tss_seg.prev_task_link,
+ ctxt->vcpu, &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ /* FIXME: need to provide precise fault address */
+ kvm_inject_page_fault(ctxt->vcpu, new_tss_base, err);
+ return ret;
+ }
+ }
+
+ return load_state_from_tss16(ctxt, ops, &tss_seg);
+}
+
+static void save_state_to_tss32(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ struct tss_segment_32 *tss)
+{
+ struct decode_cache *c = &ctxt->decode;
+
+ tss->cr3 = ops->get_cr(3, ctxt->vcpu);
+ tss->eip = c->eip;
+ tss->eflags = ctxt->eflags;
+ tss->eax = c->regs[VCPU_REGS_RAX];
+ tss->ecx = c->regs[VCPU_REGS_RCX];
+ tss->edx = c->regs[VCPU_REGS_RDX];
+ tss->ebx = c->regs[VCPU_REGS_RBX];
+ tss->esp = c->regs[VCPU_REGS_RSP];
+ tss->ebp = c->regs[VCPU_REGS_RBP];
+ tss->esi = c->regs[VCPU_REGS_RSI];
+ tss->edi = c->regs[VCPU_REGS_RDI];
+
+ tss->es = ops->get_segment_selector(VCPU_SREG_ES, ctxt->vcpu);
+ tss->cs = ops->get_segment_selector(VCPU_SREG_CS, ctxt->vcpu);
+ tss->ss = ops->get_segment_selector(VCPU_SREG_SS, ctxt->vcpu);
+ tss->ds = ops->get_segment_selector(VCPU_SREG_DS, ctxt->vcpu);
+ tss->fs = ops->get_segment_selector(VCPU_SREG_FS, ctxt->vcpu);
+ tss->gs = ops->get_segment_selector(VCPU_SREG_GS, ctxt->vcpu);
+ tss->ldt_selector = ops->get_segment_selector(VCPU_SREG_LDTR, ctxt->vcpu);
+}
+
+static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ struct tss_segment_32 *tss)
+{
+ struct decode_cache *c = &ctxt->decode;
+ int ret;
+
+ ops->set_cr(3, tss->cr3, ctxt->vcpu);
+ c->eip = tss->eip;
+ ctxt->eflags = tss->eflags | 2;
+ c->regs[VCPU_REGS_RAX] = tss->eax;
+ c->regs[VCPU_REGS_RCX] = tss->ecx;
+ c->regs[VCPU_REGS_RDX] = tss->edx;
+ c->regs[VCPU_REGS_RBX] = tss->ebx;
+ c->regs[VCPU_REGS_RSP] = tss->esp;
+ c->regs[VCPU_REGS_RBP] = tss->ebp;
+ c->regs[VCPU_REGS_RSI] = tss->esi;
+ c->regs[VCPU_REGS_RDI] = tss->edi;
+
+ /*
+ * SDM says that segment selectors are loaded before segment
+ * descriptors
+ */
+ ops->set_segment_selector(tss->ldt_selector, VCPU_SREG_LDTR, ctxt->vcpu);
+ ops->set_segment_selector(tss->es, VCPU_SREG_ES, ctxt->vcpu);
+ ops->set_segment_selector(tss->cs, VCPU_SREG_CS, ctxt->vcpu);
+ ops->set_segment_selector(tss->ss, VCPU_SREG_SS, ctxt->vcpu);
+ ops->set_segment_selector(tss->ds, VCPU_SREG_DS, ctxt->vcpu);
+ ops->set_segment_selector(tss->fs, VCPU_SREG_FS, ctxt->vcpu);
+ ops->set_segment_selector(tss->gs, VCPU_SREG_GS, ctxt->vcpu);
+
+ /*
+ * Now load segment descriptors. If fault happenes at this stage
+ * it is handled in a context of new task
+ */
+ ret = load_segment_descriptor(ctxt, ops, tss->ldt_selector, VCPU_SREG_LDTR);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->es, VCPU_SREG_ES);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->cs, VCPU_SREG_CS);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->ss, VCPU_SREG_SS);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->ds, VCPU_SREG_DS);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->fs, VCPU_SREG_FS);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = load_segment_descriptor(ctxt, ops, tss->gs, VCPU_SREG_GS);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+
+ return X86EMUL_CONTINUE;
+}
+
+static int task_switch_32(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 tss_selector, u16 old_tss_sel,
+ ulong old_tss_base, struct desc_struct *new_desc)
+{
+ struct tss_segment_32 tss_seg;
+ int ret;
+ u32 err, new_tss_base = get_desc_base(new_desc);
+
+ ret = ops->read_std(old_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+ &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ /* FIXME: need to provide precise fault address */
+ kvm_inject_page_fault(ctxt->vcpu, old_tss_base, err);
+ return ret;
+ }
+
+ save_state_to_tss32(ctxt, ops, &tss_seg);
+
+ ret = ops->write_std(old_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+ &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ /* FIXME: need to provide precise fault address */
+ kvm_inject_page_fault(ctxt->vcpu, old_tss_base, err);
+ return ret;
+ }
+
+ ret = ops->read_std(new_tss_base, &tss_seg, sizeof tss_seg, ctxt->vcpu,
+ &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ /* FIXME: need to provide precise fault address */
+ kvm_inject_page_fault(ctxt->vcpu, new_tss_base, err);
+ return ret;
+ }
+
+ if (old_tss_sel != 0xffff) {
+ tss_seg.prev_task_link = old_tss_sel;
+
+ ret = ops->write_std(new_tss_base,
+ &tss_seg.prev_task_link,
+ sizeof tss_seg.prev_task_link,
+ ctxt->vcpu, &err);
+ if (ret == X86EMUL_PROPAGATE_FAULT) {
+ /* FIXME: need to provide precise fault address */
+ kvm_inject_page_fault(ctxt->vcpu, new_tss_base, err);
+ return ret;
+ }
+ }
+
+ return load_state_from_tss32(ctxt, ops, &tss_seg);
+}
+
+static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 tss_selector, int reason)
+{
+ struct desc_struct curr_tss_desc, next_tss_desc;
+ int ret;
+ u16 old_tss_sel = ops->get_segment_selector(VCPU_SREG_TR, ctxt->vcpu);
+ ulong old_tss_base =
+ get_cached_descriptor_base(ctxt, ops, VCPU_SREG_TR);
+
+ /* FIXME: old_tss_base == ~0 ? */
+
+ ret = read_segment_descriptor(ctxt, ops, tss_selector, &next_tss_desc);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+ ret = read_segment_descriptor(ctxt, ops, old_tss_sel, &curr_tss_desc);
+ if (ret != X86EMUL_CONTINUE)
+ return ret;
+
+ /* FIXME: check that next_tss_desc is tss */
+
+ if (reason != TASK_SWITCH_IRET) {
+ if ((tss_selector & 3) > next_tss_desc.dpl ||
+ ops->cpl(ctxt->vcpu) > next_tss_desc.dpl) {
+ kvm_inject_gp(ctxt->vcpu, 0);
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+ }
+
+ if (!next_tss_desc.p || desc_limit_scaled(&next_tss_desc) < 0x67) {
+ kvm_queue_exception_e(ctxt->vcpu, TS_VECTOR,
+ tss_selector & 0xfffc);
+ return X86EMUL_PROPAGATE_FAULT;
+ }
+
+ if (reason == TASK_SWITCH_IRET || reason == TASK_SWITCH_JMP) {
+ curr_tss_desc.type &= ~(1 << 1); /* clear busy flag */
+ write_segment_descriptor(ctxt, ops, old_tss_sel,
+ &curr_tss_desc);
+ }
+
+ if (reason == TASK_SWITCH_IRET)
+ ctxt->eflags = ctxt->eflags & ~X86_EFLAGS_NT;
+
+ /* set back link to prev task only if NT bit is set in eflags
+ note that old_tss_sel is not used afetr this point */
+ if (reason != TASK_SWITCH_CALL && reason != TASK_SWITCH_GATE)
+ old_tss_sel = 0xffff;
+
+ if (next_tss_desc.type & 8)
+ ret = task_switch_32(ctxt, ops, tss_selector, old_tss_sel,
+ old_tss_base, &next_tss_desc);
+ else
+ ret = task_switch_16(ctxt, ops, tss_selector, old_tss_sel,
+ old_tss_base, &next_tss_desc);
+
+ if (reason == TASK_SWITCH_CALL || reason == TASK_SWITCH_GATE)
+ ctxt->eflags = ctxt->eflags | X86_EFLAGS_NT;
+
+ if (reason != TASK_SWITCH_IRET) {
+ next_tss_desc.type |= (1 << 1); /* set busy flag */
+ write_segment_descriptor(ctxt, ops, tss_selector,
+ &next_tss_desc);
+ }
+
+ ops->set_cr(0, ops->get_cr(0, ctxt->vcpu) | X86_CR0_TS, ctxt->vcpu);
+ ops->set_cached_descriptor(&next_tss_desc, VCPU_SREG_TR, ctxt->vcpu);
+ ops->set_segment_selector(tss_selector, VCPU_SREG_TR, ctxt->vcpu);
+
+ return ret;
+}
+
+int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
+ struct x86_emulate_ops *ops,
+ u16 tss_selector, int reason)
+{
+ struct decode_cache *c = &ctxt->decode;
+ int rc;
+
+ memset(c, 0, sizeof(struct decode_cache));
+ c->eip = ctxt->eip;
+ memcpy(c->regs, ctxt->vcpu->arch.regs, sizeof c->regs);
+
+ rc = emulator_do_task_switch(ctxt, ops, tss_selector, reason);
+
+ if (rc == X86EMUL_CONTINUE) {
+ memcpy(ctxt->vcpu->arch.regs, c->regs, sizeof c->regs);
+ kvm_rip_write(ctxt->vcpu, c->eip);
+ }
+
+ return rc;
+}
+
int
x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
{
--
1.6.5
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