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KVM: x86: Add return value to kvm_cpuid().
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Return false in kvm_cpuid() when it fails to find the cpuid
entry. Also, this routine(and its caller) is optimized with
a new argument - check_limit, so that the check_cpuid_limit()
fall back can be avoided.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Yu Zhang authored and Paolo Bonzini committed Aug 24, 2017
1 parent 3db1348 commit e911eb3
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Showing 7 changed files with 34 additions and 21 deletions.
4 changes: 2 additions & 2 deletions arch/x86/include/asm/kvm_emulate.h
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Original file line number Diff line number Diff line change
Expand Up @@ -219,8 +219,8 @@ struct x86_emulate_ops {
struct x86_instruction_info *info,
enum x86_intercept_stage stage);

void (*get_cpuid)(struct x86_emulate_ctxt *ctxt,
u32 *eax, u32 *ebx, u32 *ecx, u32 *edx);
bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt, u32 *eax, u32 *ebx,
u32 *ecx, u32 *edx, bool check_limit);
void (*set_nmi_mask)(struct x86_emulate_ctxt *ctxt, bool masked);

unsigned (*get_hflags)(struct x86_emulate_ctxt *ctxt);
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17 changes: 13 additions & 4 deletions arch/x86/kvm/cpuid.c
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Expand Up @@ -853,24 +853,33 @@ static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
}

void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
u32 *ecx, u32 *edx, bool check_limit)
{
u32 function = *eax, index = *ecx;
struct kvm_cpuid_entry2 *best;
bool entry_found = true;

best = kvm_find_cpuid_entry(vcpu, function, index);

if (!best)
if (!best) {
entry_found = false;
if (!check_limit)
goto out;

best = check_cpuid_limit(vcpu, function, index);
}

out:
if (best) {
*eax = best->eax;
*ebx = best->ebx;
*ecx = best->ecx;
*edx = best->edx;
} else
*eax = *ebx = *ecx = *edx = 0;
trace_kvm_cpuid(function, *eax, *ebx, *ecx, *edx);
trace_kvm_cpuid(function, *eax, *ebx, *ecx, *edx, entry_found);
return entry_found;
}
EXPORT_SYMBOL_GPL(kvm_cpuid);

Expand All @@ -883,7 +892,7 @@ int kvm_emulate_cpuid(struct kvm_vcpu *vcpu)

eax = kvm_register_read(vcpu, VCPU_REGS_RAX);
ecx = kvm_register_read(vcpu, VCPU_REGS_RCX);
kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx);
kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx, true);
kvm_register_write(vcpu, VCPU_REGS_RAX, eax);
kvm_register_write(vcpu, VCPU_REGS_RBX, ebx);
kvm_register_write(vcpu, VCPU_REGS_RCX, ecx);
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3 changes: 2 additions & 1 deletion arch/x86/kvm/cpuid.h
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Expand Up @@ -21,7 +21,8 @@ int kvm_vcpu_ioctl_set_cpuid2(struct kvm_vcpu *vcpu,
int kvm_vcpu_ioctl_get_cpuid2(struct kvm_vcpu *vcpu,
struct kvm_cpuid2 *cpuid,
struct kvm_cpuid_entry2 __user *entries);
void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx);
bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
u32 *ecx, u32 *edx, bool check_limit);

int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu);

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12 changes: 6 additions & 6 deletions arch/x86/kvm/emulate.c
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Expand Up @@ -2333,7 +2333,7 @@ static int emulator_has_longmode(struct x86_emulate_ctxt *ctxt)

eax = 0x80000001;
ecx = 0;
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);
return edx & bit(X86_FEATURE_LM);
}

Expand Down Expand Up @@ -2636,7 +2636,7 @@ static bool vendor_intel(struct x86_emulate_ctxt *ctxt)
u32 eax, ebx, ecx, edx;

eax = ecx = 0;
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);
return ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx
&& ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx
&& edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx;
Expand All @@ -2656,7 +2656,7 @@ static bool em_syscall_is_enabled(struct x86_emulate_ctxt *ctxt)

eax = 0x00000000;
ecx = 0x00000000;
ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);
/*
* Intel ("GenuineIntel")
* remark: Intel CPUs only support "syscall" in 64bit
Expand Down Expand Up @@ -3551,7 +3551,7 @@ static int em_movbe(struct x86_emulate_ctxt *ctxt)
/*
* Check MOVBE is set in the guest-visible CPUID leaf.
*/
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);
if (!(ecx & FFL(MOVBE)))
return emulate_ud(ctxt);

Expand Down Expand Up @@ -3865,7 +3865,7 @@ static int em_cpuid(struct x86_emulate_ctxt *ctxt)

eax = reg_read(ctxt, VCPU_REGS_RAX);
ecx = reg_read(ctxt, VCPU_REGS_RCX);
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, true);
*reg_write(ctxt, VCPU_REGS_RAX) = eax;
*reg_write(ctxt, VCPU_REGS_RBX) = ebx;
*reg_write(ctxt, VCPU_REGS_RCX) = ecx;
Expand Down Expand Up @@ -3924,7 +3924,7 @@ static int check_fxsr(struct x86_emulate_ctxt *ctxt)
{
u32 eax = 1, ebx, ecx = 0, edx;

ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, false);
if (!(edx & FFL(FXSR)))
return emulate_ud(ctxt);

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2 changes: 1 addition & 1 deletion arch/x86/kvm/svm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1593,7 +1593,7 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
}
init_vmcb(svm);

kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy);
kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy, true);
kvm_register_write(vcpu, VCPU_REGS_RDX, eax);

if (kvm_vcpu_apicv_active(vcpu) && !init_event)
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11 changes: 7 additions & 4 deletions arch/x86/kvm/trace.h
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Original file line number Diff line number Diff line change
Expand Up @@ -151,15 +151,16 @@ TRACE_EVENT(kvm_fast_mmio,
*/
TRACE_EVENT(kvm_cpuid,
TP_PROTO(unsigned int function, unsigned long rax, unsigned long rbx,
unsigned long rcx, unsigned long rdx),
TP_ARGS(function, rax, rbx, rcx, rdx),
unsigned long rcx, unsigned long rdx, bool found),
TP_ARGS(function, rax, rbx, rcx, rdx, found),

TP_STRUCT__entry(
__field( unsigned int, function )
__field( unsigned long, rax )
__field( unsigned long, rbx )
__field( unsigned long, rcx )
__field( unsigned long, rdx )
__field( bool, found )
),

TP_fast_assign(
Expand All @@ -168,11 +169,13 @@ TRACE_EVENT(kvm_cpuid,
__entry->rbx = rbx;
__entry->rcx = rcx;
__entry->rdx = rdx;
__entry->found = found;
),

TP_printk("func %x rax %lx rbx %lx rcx %lx rdx %lx",
TP_printk("func %x rax %lx rbx %lx rcx %lx rdx %lx, cpuid entry %s",
__entry->function, __entry->rax,
__entry->rbx, __entry->rcx, __entry->rdx)
__entry->rbx, __entry->rcx, __entry->rdx,
__entry->found ? "found" : "not found")
);

#define AREG(x) { APIC_##x, "APIC_" #x }
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6 changes: 3 additions & 3 deletions arch/x86/kvm/x86.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5206,10 +5206,10 @@ static int emulator_intercept(struct x86_emulate_ctxt *ctxt,
return kvm_x86_ops->check_intercept(emul_to_vcpu(ctxt), info, stage);
}

static void emulator_get_cpuid(struct x86_emulate_ctxt *ctxt,
u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
static bool emulator_get_cpuid(struct x86_emulate_ctxt *ctxt,
u32 *eax, u32 *ebx, u32 *ecx, u32 *edx, bool check_limit)
{
kvm_cpuid(emul_to_vcpu(ctxt), eax, ebx, ecx, edx);
return kvm_cpuid(emul_to_vcpu(ctxt), eax, ebx, ecx, edx, check_limit);
}

static ulong emulator_read_gpr(struct x86_emulate_ctxt *ctxt, unsigned reg)
Expand Down

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