KVM: x86: Add code to track call origin for msr assignment

In order to track who initiated the call (host or guest) to modify an msr
value I have changed function call parameters along the call path. The
specific change is to add a struct pointer parameter that points to (index,
data, caller) information rather than having this information passed as
individual parameters.

The initial use for this capability is for updating the IA32_TSC_ADJUST msr
while setting the tsc value. It is anticipated that this capability is
useful for other tasks.

Signed-off-by: Will Auld <will.auld@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

5 files changed, 56 insertions, 21 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9fb6d8da7a43..56c5dca9d78d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -620,6 +620,12 @@ struct kvm_vcpu_stat {
 
 struct x86_instruction_info;
 
+struct msr_data {
+        bool host_initiated;
+        u32 index;
+        u64 data;
+};
+
 struct kvm_x86_ops {
         int (*cpu_has_kvm_support)(void);          /* __init */
         int (*disabled_by_bios)(void);             /* __init */
@@ -642,7 +648,7 @@ struct kvm_x86_ops {
 
         void (*update_db_bp_intercept)(struct kvm_vcpu *vcpu);
         int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
-        int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
+        int (*set_msr)(struct kvm_vcpu *vcpu, struct msr_data *msr);
         u64 (*get_segment_base)(struct kvm_vcpu *vcpu, int seg);
         void (*get_segment)(struct kvm_vcpu *vcpu,
                             struct kvm_segment *var, int seg);
@@ -793,7 +799,7 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
 
 void kvm_enable_efer_bits(u64);
 int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
-int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
+int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
 
 struct x86_emulate_ctxt;
 
@@ -820,7 +826,7 @@ void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l);
 int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr);
 
 int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
-int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data);
+int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr);
 
 unsigned long kvm_get_rflags(struct kvm_vcpu *vcpu);
 void kvm_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 161a5fa66d82..fc22e58d23b7 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3127,13 +3127,15 @@ static int svm_set_vm_cr(struct kvm_vcpu *vcpu, u64 data)
         return 0;
 }
 
-static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data)
+static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
 
+        u32 ecx = msr->index;
+        u64 data = msr->data;
         switch (ecx) {
         case MSR_IA32_TSC:
-                kvm_write_tsc(vcpu, data);
+                kvm_write_tsc(vcpu, msr);
                 break;
         case MSR_STAR:
                 svm->vmcb->save.star = data;
@@ -3188,20 +3190,24 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, unsigned ecx, u64 data)
                 vcpu_unimpl(vcpu, "unimplemented wrmsr: 0x%x data 0x%llx\n", ecx, data);
                 break;
         default:
-                return kvm_set_msr_common(vcpu, ecx, data);
+                return kvm_set_msr_common(vcpu, msr);
         }
         return 0;
 }
 
 static int wrmsr_interception(struct vcpu_svm *svm)
 {
+        struct msr_data msr;
         u32 ecx = svm->vcpu.arch.regs[VCPU_REGS_RCX];
         u64 data = (svm->vcpu.arch.regs[VCPU_REGS_RAX] & -1u)
                 | ((u64)(svm->vcpu.arch.regs[VCPU_REGS_RDX] & -1u) << 32);
 
+        msr.data = data;
+        msr.index = ecx;
+        msr.host_initiated = false;
 
         svm->next_rip = kvm_rip_read(&svm->vcpu) + 2;
-        if (svm_set_msr(&svm->vcpu, ecx, data)) {
+        if (svm_set_msr(&svm->vcpu, &msr)) {
                 trace_kvm_msr_write_ex(ecx, data);
                 kvm_inject_gp(&svm->vcpu, 0);
         } else {
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 3606154bbc8b..45ffa32352f1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2220,15 +2220,17 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
  */
-static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
+static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 {
         struct vcpu_vmx *vmx = to_vmx(vcpu);
         struct shared_msr_entry *msr;
         int ret = 0;
+        u32 msr_index = msr_info->index;
+        u64 data = msr_info->data;
 
         switch (msr_index) {
         case MSR_EFER:
-                ret = kvm_set_msr_common(vcpu, msr_index, data);
+                ret = kvm_set_msr_common(vcpu, msr_info);
                 break;
 #ifdef CONFIG_X86_64
         case MSR_FS_BASE:
@@ -2254,7 +2256,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
                 vmcs_writel(GUEST_SYSENTER_ESP, data);
                 break;
         case MSR_IA32_TSC:
-                kvm_write_tsc(vcpu, data);
+                kvm_write_tsc(vcpu, msr_info);
                 break;
         case MSR_IA32_CR_PAT:
                 if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
@@ -2262,7 +2264,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
                         vcpu->arch.pat = data;
                         break;
                 }
-                ret = kvm_set_msr_common(vcpu, msr_index, data);
+                ret = kvm_set_msr_common(vcpu, msr_info);
                 break;
         case MSR_TSC_AUX:
                 if (!vmx->rdtscp_enabled)
@@ -2285,7 +2287,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
                         }
                         break;
                 }
-                ret = kvm_set_msr_common(vcpu, msr_index, data);
+                ret = kvm_set_msr_common(vcpu, msr_info);
         }
 
         return ret;
@@ -4648,11 +4650,15 @@ static int handle_rdmsr(struct kvm_vcpu *vcpu)
 
 static int handle_wrmsr(struct kvm_vcpu *vcpu)
 {
+        struct msr_data msr;
         u32 ecx = vcpu->arch.regs[VCPU_REGS_RCX];
         u64 data = (vcpu->arch.regs[VCPU_REGS_RAX] & -1u)
                 | ((u64)(vcpu->arch.regs[VCPU_REGS_RDX] & -1u) << 32);
 
-        if (vmx_set_msr(vcpu, ecx, data) != 0) {
+        msr.data = data;
+        msr.index = ecx;
+        msr.host_initiated = false;
+        if (vmx_set_msr(vcpu, &msr) != 0) {
                 trace_kvm_msr_write_ex(ecx, data);
                 kvm_inject_gp(vcpu, 0);
                 return 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fd766214d9da..95f66136f2d5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -890,9 +890,9 @@ EXPORT_SYMBOL_GPL(kvm_enable_efer_bits);
  * Returns 0 on success, non-0 otherwise.
  * Assumes vcpu_load() was already called.
  */
-int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
+int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 {
-        return kvm_x86_ops->set_msr(vcpu, msr_index, data);
+        return kvm_x86_ops->set_msr(vcpu, msr);
 }
 
 /*
@@ -900,7 +900,12 @@ int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
  */
 static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data)
 {
-        return kvm_set_msr(vcpu, index, *data);
+        struct msr_data msr;
+
+        msr.data = *data;
+        msr.index = index;
+        msr.host_initiated = true;
+        return kvm_set_msr(vcpu, &msr);
 }
 
 #ifdef CONFIG_X86_64
@@ -1130,13 +1135,14 @@ void kvm_track_tsc_matching(struct kvm_vcpu *vcpu)
 #endif
 }
 
-void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data)
+void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr)
 {
         struct kvm *kvm = vcpu->kvm;
         u64 offset, ns, elapsed;
         unsigned long flags;
         s64 usdiff;
         bool matched;
+        u64 data = msr->data;
 
         raw_spin_lock_irqsave(&kvm->arch.tsc_write_lock, flags);
         offset = kvm_x86_ops->compute_tsc_offset(vcpu, data);
@@ -1857,9 +1863,11 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
                 &vcpu->arch.st.steal, sizeof(struct kvm_steal_time));
 }
 
-int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 {
         bool pr = false;
+        u32 msr = msr_info->index;
+        u64 data = msr_info->data;
 
         switch (msr) {
         case MSR_EFER:
@@ -4531,7 +4539,12 @@ static int emulator_get_msr(struct x86_emulate_ctxt *ctxt,
 static int emulator_set_msr(struct x86_emulate_ctxt *ctxt,
                             u32 msr_index, u64 data)
 {
-        return kvm_set_msr(emul_to_vcpu(ctxt), msr_index, data);
+        struct msr_data msr;
+
+        msr.data = data;
+        msr.index = msr_index;
+        msr.host_initiated = false;
+        return kvm_set_msr(emul_to_vcpu(ctxt), &msr);
 }
 
 static int emulator_read_pmc(struct x86_emulate_ctxt *ctxt,
@@ -6375,11 +6388,15 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 int kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
 {
         int r;
+        struct msr_data msr;
 
         r = vcpu_load(vcpu);
         if (r)
                 return r;
-        kvm_write_tsc(vcpu, 0);
+        msr.data = 0x0;
+        msr.index = MSR_IA32_TSC;
+        msr.host_initiated = true;
+        kvm_write_tsc(vcpu, &msr);
         vcpu_put(vcpu);
 
         return r;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 2b5219c12ac8..e224f7a671b6 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -112,7 +112,7 @@ void kvm_before_handle_nmi(struct kvm_vcpu *vcpu);
 void kvm_after_handle_nmi(struct kvm_vcpu *vcpu);
 int kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip);
 
-void kvm_write_tsc(struct kvm_vcpu *vcpu, u64 data);
+void kvm_write_tsc(struct kvm_vcpu *vcpu, struct msr_data *msr);
 
 int kvm_read_guest_virt(struct x86_emulate_ctxt *ctxt,
         gva_t addr, void *val, unsigned int bytes,