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>

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index df53ba2..6c4f491 100644 (file)
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -135,7 +135,7 @@ struct x86_emulate_ops {
        unsigned long (*get_cached_segment_base)(int seg, struct kvm_vcpu *vcpu);
        void (*get_gdt)(struct desc_ptr *dt, struct kvm_vcpu *vcpu);
        ulong (*get_cr)(int cr, struct kvm_vcpu *vcpu);
-       void (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
+       int (*set_cr)(int cr, ulong val, struct kvm_vcpu *vcpu);
        int (*cpl)(struct kvm_vcpu *vcpu);
        void (*set_rflags)(struct kvm_vcpu *vcpu, unsigned long rflags);
        int (*get_dr)(int dr, unsigned long *dest, struct kvm_vcpu *vcpu);

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f56ec48..061f7d3 100644 (file)
--- 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 9a469df..64c6e7a 100644 (file)
--- 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)