Re: [PATCH v2 1/5] KVM: x86: Add return value to kvm_cpuid().
From: Yu Zhang
Date: Thu Aug 17 2017 - 08:45:52 EST
On 8/17/2017 8:29 PM, Paolo Bonzini wrote:
On 17/08/2017 21:52, Yu Zhang wrote:
diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
index ac15193..3e759cf 100644
--- a/arch/x86/kvm/cpuid.h
+++ b/arch/x86/kvm/cpuid.h
@@ -21,7 +21,14 @@ 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);
+
+enum {
+ NO_CHECK_LIMIT = 0,
+ CHECK_LIMIT = 1,
+};
emulate.c should not include cpuid.h. The argument can be simply a
bool, though.
Thanks, Paolo.
So we just use true/false in emulate.c & svm.c, is this OK?
BTW could you please
+bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
+ u32 *ecx, u32 *edx, int check_limit);
int cpuid_query_maxphyaddr(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index fb00559..46daa37 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -28,6 +28,7 @@
#include "x86.h"
#include "tss.h"
+#include "cpuid.h"
/*
* Operand types
@@ -2333,8 +2334,10 @@ static int emulator_has_longmode(struct x86_emulate_ctxt *ctxt)
eax = 0x80000001;
ecx = 0;
- ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
- return edx & bit(X86_FEATURE_LM);
+ if (ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx, NO_CHECK_LIMIT))
+ return edx & bit(X86_FEATURE_LM);
+ else
+ return 0;
}
#define GET_SMSTATE(type, smbase, offset) \
@@ -2636,7 +2639,7 @@ 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, NO_CHECK_LIMIT);
return ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx
&& ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx
&& edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx;
@@ -2656,7 +2659,7 @@ 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, NO_CHECK_LIMIT);
/*
* Intel ("GenuineIntel")
* remark: Intel CPUs only support "syscall" in 64bit
@@ -3551,7 +3554,7 @@ 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, CHECK_LIMIT);
This should be NO_CHECK_LIMIT.
Otherwise okay!
Then I guess check_fxsr() should also use NO_CHECK_LIMIT('false' for a
bool argument),
because it's also for eax=1?
And what about svm_vcpu_reset()?
I am not sure if leaf 1 is always available. And if the answer is yes, I
do not think any of these
3 places(em_movbe/check_fxsr/svm_vcpu_reset) will need to fall back to
check_cpuid_limit(),
nor do we need to check the return value of get_cpuid(). Do you agree? :-)
Yu
Paolo
if (!(ecx & FFL(MOVBE)))
return emulate_ud(ctxt);
@@ -3865,7 +3868,7 @@ 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, CHECK_LIMIT);
*reg_write(ctxt, VCPU_REGS_RAX) = eax;
*reg_write(ctxt, VCPU_REGS_RBX) = ebx;
*reg_write(ctxt, VCPU_REGS_RCX) = ecx;
@@ -3924,7 +3927,7 @@ 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, CHECK_LIMIT);
if (!(edx & FFL(FXSR)))
return emulate_ud(ctxt);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1fa9ee5..9def4a8 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1580,7 +1580,7 @@ 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, CHECK_LIMIT);
kvm_register_write(vcpu, VCPU_REGS_RDX, eax);
if (kvm_vcpu_apicv_active(vcpu) && !init_event)
diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 0a6cc67..8a202c4 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -151,8 +151,8 @@ 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 )
@@ -160,6 +160,7 @@ TRACE_EVENT(kvm_cpuid,
__field( unsigned long, rbx )
__field( unsigned long, rcx )
__field( unsigned long, rdx )
+ __field( bool, found )
),
TP_fast_assign(
@@ -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 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e40a779..ee99fc1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5213,10 +5213,10 @@ 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, int 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)