KVM: x86 emulator: introduce struct x86_exception to communicate faults

Introduce a structure that can contain an exception to be passed back
to main kvm code.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

3 files changed, 38 insertions, 12 deletions

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index b48c133c95ab..b7c11270ae8f 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -15,6 +15,12 @@
 
 struct x86_emulate_ctxt;
 
+struct x86_exception {
+        u8 vector;
+        bool error_code_valid;
+        u16 error_code;
+};
+
 /*
  * x86_emulate_ops:
  *
@@ -229,9 +235,8 @@ struct x86_emulate_ctxt {
 
         bool perm_ok; /* do not check permissions if true */
 
-        int exception; /* exception that happens during emulation or -1 */
-        u32 error_code; /* error code for exception */
-        bool error_code_valid;
+        bool have_exception;
+        struct x86_exception exception;
 
         /* decode cache */
         struct decode_cache decode;
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index bdbbb1839e89..18596e6649aa 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -469,9 +469,9 @@ static ulong linear(struct x86_emulate_ctxt *ctxt,
 static void emulate_exception(struct x86_emulate_ctxt *ctxt, int vec,
                                       u32 error, bool valid)
 {
-        ctxt->exception = vec;
-        ctxt->error_code = error;
-        ctxt->error_code_valid = valid;
+        ctxt->exception.vector = vec;
+        ctxt->exception.error_code = error;
+        ctxt->exception.error_code_valid = valid;
 }
 
 static void emulate_gp(struct x86_emulate_ctxt *ctxt, int err)
@@ -3015,23 +3015,27 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 
         if (ctxt->mode == X86EMUL_MODE_PROT64 && (c->d & No64)) {
                 emulate_ud(ctxt);
+                rc = X86EMUL_PROPAGATE_FAULT;
                 goto done;
         }
 
         /* LOCK prefix is allowed only with some instructions */
         if (c->lock_prefix && (!(c->d & Lock) || c->dst.type != OP_MEM)) {
                 emulate_ud(ctxt);
+                rc = X86EMUL_PROPAGATE_FAULT;
                 goto done;
         }
 
         if ((c->d & SrcMask) == SrcMemFAddr && c->src.type != OP_MEM) {
                 emulate_ud(ctxt);
+                rc = X86EMUL_PROPAGATE_FAULT;
                 goto done;
         }
 
         /* Privileged instruction can be executed only in CPL=0 */
         if ((c->d & Priv) && ops->cpl(ctxt->vcpu)) {
                 emulate_gp(ctxt, 0);
+                rc = X86EMUL_PROPAGATE_FAULT;
                 goto done;
         }
 
@@ -3210,6 +3214,7 @@ special_insn:
         case 0x8c:  /* mov r/m, sreg */
                 if (c->modrm_reg > VCPU_SREG_GS) {
                         emulate_ud(ctxt);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
                 c->dst.val = ops->get_segment_selector(c->modrm_reg, ctxt->vcpu);
@@ -3225,6 +3230,7 @@ special_insn:
                 if (c->modrm_reg == VCPU_SREG_CS ||
                     c->modrm_reg > VCPU_SREG_GS) {
                         emulate_ud(ctxt);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
 
@@ -3357,6 +3363,7 @@ special_insn:
                 c->dst.bytes = min(c->dst.bytes, 4u);
                 if (!emulator_io_permited(ctxt, ops, c->src.val, c->dst.bytes)) {
                         emulate_gp(ctxt, 0);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
                 if (!pio_in_emulated(ctxt, ops, c->dst.bytes, c->src.val,
@@ -3371,6 +3378,7 @@ special_insn:
                 if (!emulator_io_permited(ctxt, ops, c->dst.val,
                                           c->src.bytes)) {
                         emulate_gp(ctxt, 0);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
                 ops->pio_out_emulated(c->src.bytes, c->dst.val,
@@ -3396,6 +3404,7 @@ special_insn:
         case 0xfa: /* cli */
                 if (emulator_bad_iopl(ctxt, ops)) {
                         emulate_gp(ctxt, 0);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 } else
                         ctxt->eflags &= ~X86_EFLAGS_IF;
@@ -3403,6 +3412,7 @@ special_insn:
         case 0xfb: /* sti */
                 if (emulator_bad_iopl(ctxt, ops)) {
                         emulate_gp(ctxt, 0);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 } else {
                         ctxt->interruptibility = KVM_X86_SHADOW_INT_STI;
@@ -3475,6 +3485,8 @@ writeback:
         ctxt->eip = c->eip;
 
 done:
+        if (rc == X86EMUL_PROPAGATE_FAULT)
+                ctxt->have_exception = true;
         return (rc == X86EMUL_UNHANDLEABLE) ? EMULATION_FAILED : EMULATION_OK;
 
 twobyte_insn:
@@ -3537,6 +3549,7 @@ twobyte_insn:
                         break;
                 case 5: /* not defined */
                         emulate_ud(ctxt);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 case 7: /* invlpg*/
                         emulate_invlpg(ctxt->vcpu,
@@ -3567,6 +3580,7 @@ twobyte_insn:
                 case 5 ... 7:
                 case 9 ... 15:
                         emulate_ud(ctxt);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
                 c->dst.val = ops->get_cr(c->modrm_reg, ctxt->vcpu);
@@ -3575,6 +3589,7 @@ twobyte_insn:
                 if ((ops->get_cr(4, ctxt->vcpu) & X86_CR4_DE) &&
                     (c->modrm_reg == 4 || c->modrm_reg == 5)) {
                         emulate_ud(ctxt);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
                 ops->get_dr(c->modrm_reg, &c->dst.val, ctxt->vcpu);
@@ -3582,6 +3597,7 @@ twobyte_insn:
         case 0x22: /* mov reg, cr */
                 if (ops->set_cr(c->modrm_reg, c->src.val, ctxt->vcpu)) {
                         emulate_gp(ctxt, 0);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
                 c->dst.type = OP_NONE;
@@ -3590,6 +3606,7 @@ twobyte_insn:
                 if ((ops->get_cr(4, ctxt->vcpu) & X86_CR4_DE) &&
                     (c->modrm_reg == 4 || c->modrm_reg == 5)) {
                         emulate_ud(ctxt);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
 
@@ -3598,6 +3615,7 @@ twobyte_insn:
                                  ~0ULL : ~0U), ctxt->vcpu) < 0) {
                         /* #UD condition is already handled by the code above */
                         emulate_gp(ctxt, 0);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
 
@@ -3609,6 +3627,7 @@ twobyte_insn:
                         | ((u64)c->regs[VCPU_REGS_RDX] << 32);
                 if (ops->set_msr(ctxt->vcpu, c->regs[VCPU_REGS_RCX], msr_data)) {
                         emulate_gp(ctxt, 0);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 }
                 rc = X86EMUL_CONTINUE;
@@ -3617,6 +3636,7 @@ twobyte_insn:
                 /* rdmsr */
                 if (ops->get_msr(ctxt->vcpu, c->regs[VCPU_REGS_RCX], &msr_data)) {
                         emulate_gp(ctxt, 0);
+                        rc = X86EMUL_PROPAGATE_FAULT;
                         goto done;
                 } else {
                         c->regs[VCPU_REGS_RAX] = (u32)msr_data;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 651cf9004fbe..0c908321e900 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4254,12 +4254,13 @@ static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
 static void inject_emulated_exception(struct kvm_vcpu *vcpu)
 {
         struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt;
-        if (ctxt->exception == PF_VECTOR)
+        if (ctxt->exception.vector == PF_VECTOR)
                 kvm_propagate_fault(vcpu);
-        else if (ctxt->error_code_valid)
-                kvm_queue_exception_e(vcpu, ctxt->exception, ctxt->error_code);
+        else if (ctxt->exception.error_code_valid)
+                kvm_queue_exception_e(vcpu, ctxt->exception.vector,
+                                      ctxt->exception.error_code);
         else
-                kvm_queue_exception(vcpu, ctxt->exception);
+                kvm_queue_exception(vcpu, ctxt->exception.vector);
 }
 
 static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
@@ -4371,7 +4372,7 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
         if (!(emulation_type & EMULTYPE_NO_DECODE)) {
                 init_emulate_ctxt(vcpu);
                 vcpu->arch.emulate_ctxt.interruptibility = 0;
-                vcpu->arch.emulate_ctxt.exception = -1;
+                vcpu->arch.emulate_ctxt.have_exception = false;
                 vcpu->arch.emulate_ctxt.perm_ok = false;
 
                 r = x86_decode_insn(&vcpu->arch.emulate_ctxt);
@@ -4437,7 +4438,7 @@ restart:
         }
 
 done:
-        if (vcpu->arch.emulate_ctxt.exception >= 0) {
+        if (vcpu->arch.emulate_ctxt.have_exception) {
                 inject_emulated_exception(vcpu);
                 r = EMULATE_DONE;
         } else if (vcpu->arch.pio.count) {