Currently kvm_get_inst() returns KVM_INVALID_INST in the event of a
fault reading the guest instruction. This has the rather arbitrary magic
value 0xdeadbeef. This API isn't very robust, and in fact 0xdeadbeef is
a valid MIPS64 instruction encoding, namely "ld t1,-16657(s5)".
Therefore change the kvm_get_inst() API to return 0 or -EFAULT, and to
return the instruction via a u32 *out argument. We can then drop the
KVM_INVALID_INST definition entirely.
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
---
arch/mips/include/asm/kvm_host.h | 3 +-
arch/mips/kvm/emulate.c | 90 ++++++++++++++++-----------------
arch/mips/kvm/mips.c | 7 ++-
arch/mips/kvm/mmu.c | 9 +--
4 files changed, 56 insertions(+), 53 deletions(-)
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 3c39ccd8856e..b0936a4d931a 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -104,7 +104,6 @@
#define KVM_GUEST_KSEG23ADDR(a) (KVM_GUEST_CPHYSADDR(a) | KVM_GUEST_KSEG23)
#define KVM_INVALID_PAGE 0xdeadbeef
-#define KVM_INVALID_INST 0xdeadbeef
#define KVM_INVALID_ADDR 0xdeadbeef
/*
@@ -637,7 +636,7 @@ void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr,
bool user);
/* Emulation */
-u32 kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu);
+int kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu, u32 *out);
enum emulation_result update_pc(struct kvm_vcpu *vcpu, u32 cause);
/**
diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
index 67ea39973b96..b906fc0589f3 100644
--- a/arch/mips/kvm/emulate.c
+++ b/arch/mips/kvm/emulate.c
@@ -38,23 +38,25 @@
* Compute the return address and do emulate branch simulation, if required.
* This function should be called only in branch delay slot active.
*/
-unsigned long kvm_compute_return_epc(struct kvm_vcpu *vcpu,
- unsigned long instpc)
+static int kvm_compute_return_epc(struct kvm_vcpu *vcpu, unsigned long instpc,
+ unsigned long *out)
{
unsigned int dspcontrol;
union mips_instruction insn;
struct kvm_vcpu_arch *arch = &vcpu->arch;
long epc = instpc;
- long nextpc = KVM_INVALID_INST;
+ long nextpc;
+ int err;
- if (epc & 3)
- goto unaligned;
+ if (epc & 3) {
+ kvm_err("%s: unaligned epc\n", __func__);
+ return -EINVAL;
+ }
/* Read the instruction */
- insn.word = kvm_get_inst((u32 *) epc, vcpu);
-
- if (insn.word == KVM_INVALID_INST)
- return KVM_INVALID_INST;
+ err = kvm_get_inst((u32 *)epc, vcpu, &insn.word);
+ if (err)
+ return err;
switch (insn.i_format.opcode) {
/* jr and jalr are in r_format format. */
@@ -66,6 +68,8 @@ unsigned long kvm_compute_return_epc(struct kvm_vcpu *vcpu,
case jr_op:
nextpc = arch->gprs[insn.r_format.rs];
break;
+ default:
+ return -EINVAL;
}
break;
@@ -114,8 +118,11 @@ unsigned long kvm_compute_return_epc(struct kvm_vcpu *vcpu,
nextpc = epc;
break;
case bposge32_op:
- if (!cpu_has_dsp)
- goto sigill;
+ if (!cpu_has_dsp) {
+ kvm_err("%s: DSP branch but not DSP ASE\n",
+ __func__);
+ return -EINVAL;
+ }
dspcontrol = rddsp(0x01);
@@ -125,6 +132,8 @@ unsigned long kvm_compute_return_epc(struct kvm_vcpu *vcpu,
epc += 8;
nextpc = epc;
break;
+ default:
+ return -EINVAL;
}
break;
@@ -189,7 +198,7 @@ unsigned long kvm_compute_return_epc(struct kvm_vcpu *vcpu,
/* And now the FPA/cp1 branch instructions. */
case cop1_op:
kvm_err("%s: unsupported cop1_op\n", __func__);
- break;
+ return -EINVAL;
#ifdef CONFIG_CPU_MIPSR6
/* R6 added the following compact branches with forbidden slots */
@@ -198,19 +207,19 @@ unsigned long kvm_compute_return_epc(struct kvm_vcpu *vcpu,
/* only rt == 0 isn't compact branch */
if (insn.i_format.rt != 0)
goto compact_branch;
- break;
+ return -EINVAL;
case pop10_op:
case pop30_op:
/* only rs == rt == 0 is reserved, rest are compact branches */
if (insn.i_format.rs != 0 || insn.i_format.rt != 0)
goto compact_branch;
- break;
+ return -EINVAL;
case pop66_op:
case pop76_op:
/* only rs == 0 isn't compact branch */
if (insn.i_format.rs != 0)
goto compact_branch;
- break;
+ return -EINVAL;
compact_branch:
/*
* If we've hit an exception on the forbidden slot, then
@@ -221,42 +230,32 @@ unsigned long kvm_compute_return_epc(struct kvm_vcpu *vcpu,
break;
#else
compact_branch:
- /* Compact branches not supported before R6 */
- break;
+ /* Fall through - Compact branches not supported before R6 */
#endif
+ default:
+ return -EINVAL;
}
- return nextpc;
-
-unaligned:
- kvm_err("%s: unaligned epc\n", __func__);
- return nextpc;
-
-sigill:
- kvm_err("%s: DSP branch but not DSP ASE\n", __func__);
- return nextpc;
+ *out = nextpc;
+ return 0;
}
enum emulation_result update_pc(struct kvm_vcpu *vcpu, u32 cause)
{
- unsigned long branch_pc;
- enum emulation_result er = EMULATE_DONE;
+ int err;
if (cause & CAUSEF_BD) {
- branch_pc = kvm_compute_return_epc(vcpu, vcpu->arch.pc);
- if (branch_pc == KVM_INVALID_INST) {
- er = EMULATE_FAIL;
- } else {
- vcpu->arch.pc = branch_pc;
- kvm_debug("BD update_pc(): New PC: %#lx\n",
- vcpu->arch.pc);
- }
- } else
+ err = kvm_compute_return_epc(vcpu, vcpu->arch.pc,
+ &vcpu->arch.pc);
+ if (err)
+ return EMULATE_FAIL;
+ } else {
vcpu->arch.pc += 4;
+ }
kvm_debug("update_pc(): New PC: %#lx\n", vcpu->arch.pc);
- return er;
+ return EMULATE_DONE;
}
/**
@@ -1835,12 +1834,14 @@ enum emulation_result kvm_mips_emulate_inst(u32 cause, u32 *opc,
{
union mips_instruction inst;
enum emulation_result er = EMULATE_DONE;
+ int err;
/* Fetch the instruction. */
if (cause & CAUSEF_BD)
opc += 1;
-
- inst.word = kvm_get_inst(opc, vcpu);
+ err = kvm_get_inst(opc, vcpu, &inst.word);
+ if (err)
+ return EMULATE_FAIL;
switch (inst.r_format.opcode) {
case cop0_op:
@@ -2419,6 +2420,7 @@ enum emulation_result kvm_mips_handle_ri(u32 cause, u32 *opc,
enum emulation_result er = EMULATE_DONE;
unsigned long curr_pc;
union mips_instruction inst;
+ int err;
/*
* Update PC and hold onto current PC in case there is
@@ -2432,11 +2434,9 @@ enum emulation_result kvm_mips_handle_ri(u32 cause, u32 *opc,
/* Fetch the instruction. */
if (cause & CAUSEF_BD)
opc += 1;
-
- inst.word = kvm_get_inst(opc, vcpu);
-
- if (inst.word == KVM_INVALID_INST) {
- kvm_err("%s: Cannot get inst @ %p\n", __func__, opc);
+ err = kvm_get_inst(opc, vcpu, &inst.word);
+ if (err) {
+ kvm_err("%s: Cannot get inst @ %p (%d)\n", __func__, opc, err);
return EMULATE_FAIL;
}
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 001349124bad..69775fb9c408 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -1348,6 +1348,7 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
u32 __user *opc = (u32 __user *) vcpu->arch.pc;
unsigned long badvaddr = vcpu->arch.host_cp0_badvaddr;
enum emulation_result er = EMULATE_DONE;
+ u32 inst;
int ret = RESUME_GUEST;
/* re-enable HTW before enabling interrupts */
@@ -1472,8 +1473,12 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
break;
default:
+ if (cause & CAUSEF_BD)
+ opc += 1;
+ inst = 0;
+ kvm_get_inst(opc, vcpu, &inst);
kvm_err("Exception Code: %d, not yet handled, @ PC: %p, inst: 0x%08x BadVaddr: %#lx Status: %#lx\n",
- exccode, opc, kvm_get_inst(opc, vcpu), badvaddr,
+ exccode, opc, inst, badvaddr,
kvm_read_c0_guest_status(vcpu->arch.cop0));
kvm_arch_vcpu_dump_regs(vcpu);
run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index aab604e75d3b..6379ac1bc7b9 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -503,16 +503,15 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
local_irq_restore(flags);
}
-u32 kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu)
+int kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu, u32 *out)
{
- u32 inst;
int err;
- err = get_user(inst, opc);
+ err = get_user(*out, opc);
if (unlikely(err)) {
kvm_err("%s: illegal address: %p\n", __func__, opc);
- return KVM_INVALID_INST;
+ return -EFAULT;
}
- return inst;
+ return 0;
}
--
git-series 0.8.10
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