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KVM: x86: Add code to track call origin for msr assignment
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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>
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Will Auld authored and Marcelo Tosatti committed Nov 30, 2012
1 parent 5419369 commit 8fe8ab4
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Showing 5 changed files with 56 additions and 21 deletions.
12 changes: 9 additions & 3 deletions arch/x86/include/asm/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand All @@ -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);
Expand Down Expand Up @@ -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;

Expand All @@ -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);
Expand Down
14 changes: 10 additions & 4 deletions arch/x86/kvm/svm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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 {
Expand Down
18 changes: 12 additions & 6 deletions arch/x86/kvm/vmx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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:
Expand All @@ -2254,15 +2256,15 @@ 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) {
vmcs_write64(GUEST_IA32_PAT, 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)
Expand All @@ -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;
Expand Down Expand Up @@ -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;
Expand Down
31 changes: 24 additions & 7 deletions arch/x86/kvm/x86.c
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Original file line number Diff line number Diff line change
Expand Up @@ -890,17 +890,22 @@ 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);
}

/*
* Adapt set_msr() to msr_io()'s calling convention
*/
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
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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:
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -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;
Expand Down
2 changes: 1 addition & 1 deletion arch/x86/kvm/x86.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down

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