KVM: x86 emulator: make set_cr() callback return error if it fails

Make set_cr() callback return error if it fails instead of injecting #GP
behind emulator's back.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

2 files changed, 83 insertions, 75 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f56ec486393e..061f7d37c9f7 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2272,7 +2272,10 @@ static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt,
         struct decode_cache *c = &ctxt->decode;
         int ret;
 
-        ops->set_cr(3, tss->cr3, ctxt->vcpu);
+        if (ops->set_cr(3, tss->cr3, ctxt->vcpu)) {
+                kvm_inject_gp(ctxt->vcpu, 0);
+                return X86EMUL_PROPAGATE_FAULT;
+        }
         c->eip = tss->eip;
         ctxt->eflags = tss->eflags | 2;
         c->regs[VCPU_REGS_RAX] = tss->eax;
@@ -3135,7 +3138,10 @@ twobyte_insn:
                 c->dst.type = OP_NONE;  /* no writeback */
                 break;
         case 0x22: /* mov reg, cr */
-                ops->set_cr(c->modrm_reg, c->modrm_val, ctxt->vcpu);
+                if (ops->set_cr(c->modrm_reg, c->modrm_val, ctxt->vcpu)) {
+                        kvm_inject_gp(ctxt->vcpu, 0);
+                        goto done;
+                }
                 c->dst.type = OP_NONE;
                 break;
         case 0x23: /* mov from reg to dr */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9a469df6011c..64c6e7a31411 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -414,57 +414,49 @@ out:
         return changed;
 }
 
-void kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
+static int __kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 {
         cr0 |= X86_CR0_ET;
 
 #ifdef CONFIG_X86_64
-        if (cr0 & 0xffffffff00000000UL) {
-                kvm_inject_gp(vcpu, 0);
-                return;
-        }
+        if (cr0 & 0xffffffff00000000UL)
+                return 1;
 #endif
 
         cr0 &= ~CR0_RESERVED_BITS;
 
-        if ((cr0 & X86_CR0_NW) && !(cr0 & X86_CR0_CD)) {
-                kvm_inject_gp(vcpu, 0);
-                return;
-        }
+        if ((cr0 & X86_CR0_NW) && !(cr0 & X86_CR0_CD))
+                return 1;
 
-        if ((cr0 & X86_CR0_PG) && !(cr0 & X86_CR0_PE)) {
-                kvm_inject_gp(vcpu, 0);
-                return;
-        }
+        if ((cr0 & X86_CR0_PG) && !(cr0 & X86_CR0_PE))
+                return 1;
 
         if (!is_paging(vcpu) && (cr0 & X86_CR0_PG)) {
 #ifdef CONFIG_X86_64
                 if ((vcpu->arch.efer & EFER_LME)) {
                         int cs_db, cs_l;
 
-                        if (!is_pae(vcpu)) {
-                                kvm_inject_gp(vcpu, 0);
-                                return;
-                        }
+                        if (!is_pae(vcpu))
+                                return 1;
                         kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
-                        if (cs_l) {
-                                kvm_inject_gp(vcpu, 0);
-                                return;
-
-                        }
+                        if (cs_l)
+                                return 1;
                 } else
 #endif
-                if (is_pae(vcpu) && !load_pdptrs(vcpu, vcpu->arch.cr3)) {
-                        kvm_inject_gp(vcpu, 0);
-                        return;
-                }
-
+                if (is_pae(vcpu) && !load_pdptrs(vcpu, vcpu->arch.cr3))
+                        return 1;
         }
 
         kvm_x86_ops->set_cr0(vcpu, cr0);
 
         kvm_mmu_reset_context(vcpu);
-        return;
+        return 0;
+}
+
+void kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
+{
+        if (__kvm_set_cr0(vcpu, cr0))
+                kvm_inject_gp(vcpu, 0);
 }
 EXPORT_SYMBOL_GPL(kvm_set_cr0);
 
@@ -474,61 +466,56 @@ void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw)
 }
 EXPORT_SYMBOL_GPL(kvm_lmsw);
 
-void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
+int __kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 {
         unsigned long old_cr4 = kvm_read_cr4(vcpu);
         unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE;
 
-        if (cr4 & CR4_RESERVED_BITS) {
-                kvm_inject_gp(vcpu, 0);
-                return;
-        }
+        if (cr4 & CR4_RESERVED_BITS)
+                return 1;
 
         if (is_long_mode(vcpu)) {
-                if (!(cr4 & X86_CR4_PAE)) {
-                        kvm_inject_gp(vcpu, 0);
-                        return;
-                }
+                if (!(cr4 & X86_CR4_PAE))
+                        return 1;
         } else if (is_paging(vcpu) && (cr4 & X86_CR4_PAE)
                    && ((cr4 ^ old_cr4) & pdptr_bits)
-                   && !load_pdptrs(vcpu, vcpu->arch.cr3)) {
-                kvm_inject_gp(vcpu, 0);
-                return;
-        }
+                   && !load_pdptrs(vcpu, vcpu->arch.cr3))
+                return 1;
+
+        if (cr4 & X86_CR4_VMXE)
+                return 1;
 
-        if (cr4 & X86_CR4_VMXE) {
-                kvm_inject_gp(vcpu, 0);
-                return;
-        }
         kvm_x86_ops->set_cr4(vcpu, cr4);
         vcpu->arch.cr4 = cr4;
         kvm_mmu_reset_context(vcpu);
+
+        return 0;
+}
+
+void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
+{
+        if (__kvm_set_cr4(vcpu, cr4))
+                kvm_inject_gp(vcpu, 0);
 }
 EXPORT_SYMBOL_GPL(kvm_set_cr4);
 
-void kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
+static int __kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
 {
         if (cr3 == vcpu->arch.cr3 && !pdptrs_changed(vcpu)) {
                 kvm_mmu_sync_roots(vcpu);
                 kvm_mmu_flush_tlb(vcpu);
-                return;
+                return 0;
         }
 
         if (is_long_mode(vcpu)) {
-                if (cr3 & CR3_L_MODE_RESERVED_BITS) {
-                        kvm_inject_gp(vcpu, 0);
-                        return;
-                }
+                if (cr3 & CR3_L_MODE_RESERVED_BITS)
+                        return 1;
         } else {
                 if (is_pae(vcpu)) {
-                        if (cr3 & CR3_PAE_RESERVED_BITS) {
-                                kvm_inject_gp(vcpu, 0);
-                                return;
-                        }
-                        if (is_paging(vcpu) && !load_pdptrs(vcpu, cr3)) {
-                                kvm_inject_gp(vcpu, 0);
-                                return;
-                        }
+                        if (cr3 & CR3_PAE_RESERVED_BITS)
+                                return 1;
+                        if (is_paging(vcpu) && !load_pdptrs(vcpu, cr3))
+                                return 1;
                 }
                 /*
                  * We don't check reserved bits in nonpae mode, because
@@ -546,24 +533,34 @@ void kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
          * to debug) behavior on the guest side.
          */
         if (unlikely(!gfn_to_memslot(vcpu->kvm, cr3 >> PAGE_SHIFT)))
+                return 1;
+        vcpu->arch.cr3 = cr3;
+        vcpu->arch.mmu.new_cr3(vcpu);
+        return 0;
+}
+
+void kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
+{
+        if (__kvm_set_cr3(vcpu, cr3))
                 kvm_inject_gp(vcpu, 0);
-        else {
-                vcpu->arch.cr3 = cr3;
-                vcpu->arch.mmu.new_cr3(vcpu);
-        }
 }
 EXPORT_SYMBOL_GPL(kvm_set_cr3);
 
-void kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)
+int __kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)
 {
-        if (cr8 & CR8_RESERVED_BITS) {
-                kvm_inject_gp(vcpu, 0);
-                return;
-        }
+        if (cr8 & CR8_RESERVED_BITS)
+                return 1;
         if (irqchip_in_kernel(vcpu->kvm))
                 kvm_lapic_set_tpr(vcpu, cr8);
         else
                 vcpu->arch.cr8 = cr8;
+        return 0;
+}
+
+void kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8)
+{
+        if (__kvm_set_cr8(vcpu, cr8))
+                kvm_inject_gp(vcpu, 0);
 }
 EXPORT_SYMBOL_GPL(kvm_set_cr8);
 
@@ -3681,27 +3678,32 @@ static unsigned long emulator_get_cr(int cr, struct kvm_vcpu *vcpu)
         return value;
 }
 
-static void emulator_set_cr(int cr, unsigned long val, struct kvm_vcpu *vcpu)
+static int emulator_set_cr(int cr, unsigned long val, struct kvm_vcpu *vcpu)
 {
+        int res = 0;
+
         switch (cr) {
         case 0:
-                kvm_set_cr0(vcpu, mk_cr_64(kvm_read_cr0(vcpu), val));
+                res = __kvm_set_cr0(vcpu, mk_cr_64(kvm_read_cr0(vcpu), val));
                 break;
         case 2:
                 vcpu->arch.cr2 = val;
                 break;
         case 3:
-                kvm_set_cr3(vcpu, val);
+                res = __kvm_set_cr3(vcpu, val);
                 break;
         case 4:
-                kvm_set_cr4(vcpu, mk_cr_64(kvm_read_cr4(vcpu), val));
+                res = __kvm_set_cr4(vcpu, mk_cr_64(kvm_read_cr4(vcpu), val));
                 break;
         case 8:
-                kvm_set_cr8(vcpu, val & 0xfUL);
+                res = __kvm_set_cr8(vcpu, val & 0xfUL);
                 break;
         default:
                 vcpu_printf(vcpu, "%s: unexpected cr %u\n", __func__, cr);
+                res = -1;
         }
+
+        return res;
 }
 
 static int emulator_get_cpl(struct kvm_vcpu *vcpu)