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KVM: x86 emulator: make set_cr() callback return error if it fails
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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>
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Gleb Natapov authored and Avi Kivity committed Aug 1, 2010
1 parent 79168fd commit 0f12244
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Showing 3 changed files with 84 additions and 76 deletions.
2 changes: 1 addition & 1 deletion arch/x86/include/asm/kvm_emulate.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down
10 changes: 8 additions & 2 deletions arch/x86/kvm/emulate.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -3135,7 +3138,10 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
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 */
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148 changes: 75 additions & 73 deletions arch/x86/kvm/x86.c
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Original file line number Diff line number Diff line change
Expand Up @@ -414,57 +414,49 @@ static bool pdptrs_changed(struct kvm_vcpu *vcpu)
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);

Expand All @@ -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
Expand All @@ -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);

Expand Down Expand Up @@ -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)
Expand Down

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