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xen/PMU: PMU emulation code
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Add PMU emulation code that runs when we are processing a PMU interrupt.
This code will allow us not to trap to hypervisor on each MSR/LVTPC access
(of which there may be quite a few in the handler).

Signed-off-by: Boris Ostrovsky <[email protected]>
Reviewed-by: David Vrabel <[email protected]>
Signed-off-by: David Vrabel <[email protected]>
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Boris Ostrovsky authored and David Vrabel committed Aug 20, 2015
1 parent 6b08cd6 commit bf6dfb1
Showing 1 changed file with 185 additions and 29 deletions.
214 changes: 185 additions & 29 deletions arch/x86/xen/pmu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13,11 +13,20 @@
/* x86_pmu.handle_irq definition */
#include "../kernel/cpu/perf_event.h"

#define XENPMU_IRQ_PROCESSING 1
struct xenpmu {
/* Shared page between hypervisor and domain */
struct xen_pmu_data *xenpmu_data;

/* Shared page between hypervisor and domain */
static DEFINE_PER_CPU(struct xen_pmu_data *, xenpmu_shared);
#define get_xenpmu_data() per_cpu(xenpmu_shared, smp_processor_id())
uint8_t flags;
};
static DEFINE_PER_CPU(struct xenpmu, xenpmu_shared);
#define get_xenpmu_data() (this_cpu_ptr(&xenpmu_shared)->xenpmu_data)
#define get_xenpmu_flags() (this_cpu_ptr(&xenpmu_shared)->flags)

/* Macro for computing address of a PMU MSR bank */
#define field_offset(ctxt, field) ((void *)((uintptr_t)ctxt + \
(uintptr_t)ctxt->field))

/* AMD PMU */
#define F15H_NUM_COUNTERS 6
Expand Down Expand Up @@ -169,19 +178,124 @@ static int is_intel_pmu_msr(u32 msr_index, int *type, int *index)
}
}

bool pmu_msr_read(unsigned int msr, uint64_t *val, int *err)
static bool xen_intel_pmu_emulate(unsigned int msr, u64 *val, int type,
int index, bool is_read)
{
uint64_t *reg = NULL;
struct xen_pmu_intel_ctxt *ctxt;
uint64_t *fix_counters;
struct xen_pmu_cntr_pair *arch_cntr_pair;
struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
uint8_t xenpmu_flags = get_xenpmu_flags();


if (!xenpmu_data || !(xenpmu_flags & XENPMU_IRQ_PROCESSING))
return false;

ctxt = &xenpmu_data->pmu.c.intel;

switch (msr) {
case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
reg = &ctxt->global_ovf_ctrl;
break;
case MSR_CORE_PERF_GLOBAL_STATUS:
reg = &ctxt->global_status;
break;
case MSR_CORE_PERF_GLOBAL_CTRL:
reg = &ctxt->global_ctrl;
break;
case MSR_CORE_PERF_FIXED_CTR_CTRL:
reg = &ctxt->fixed_ctrl;
break;
default:
switch (type) {
case MSR_TYPE_COUNTER:
fix_counters = field_offset(ctxt, fixed_counters);
reg = &fix_counters[index];
break;
case MSR_TYPE_ARCH_COUNTER:
arch_cntr_pair = field_offset(ctxt, arch_counters);
reg = &arch_cntr_pair[index].counter;
break;
case MSR_TYPE_ARCH_CTRL:
arch_cntr_pair = field_offset(ctxt, arch_counters);
reg = &arch_cntr_pair[index].control;
break;
default:
return false;
}
}

if (reg) {
if (is_read)
*val = *reg;
else {
*reg = *val;

if (msr == MSR_CORE_PERF_GLOBAL_OVF_CTRL)
ctxt->global_status &= (~(*val));
}
return true;
}

return false;
}

static bool xen_amd_pmu_emulate(unsigned int msr, u64 *val, bool is_read)
{
uint64_t *reg = NULL;
int i, off = 0;
struct xen_pmu_amd_ctxt *ctxt;
uint64_t *counter_regs, *ctrl_regs;
struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
uint8_t xenpmu_flags = get_xenpmu_flags();

if (!xenpmu_data || !(xenpmu_flags & XENPMU_IRQ_PROCESSING))
return false;

if (k7_counters_mirrored &&
((msr >= MSR_K7_EVNTSEL0) && (msr <= MSR_K7_PERFCTR3)))
msr = get_fam15h_addr(msr);

ctxt = &xenpmu_data->pmu.c.amd;
for (i = 0; i < amd_num_counters; i++) {
if (msr == amd_ctrls_base + off) {
ctrl_regs = field_offset(ctxt, ctrls);
reg = &ctrl_regs[i];
break;
} else if (msr == amd_counters_base + off) {
counter_regs = field_offset(ctxt, counters);
reg = &counter_regs[i];
break;
}
off += amd_msr_step;
}

if (reg) {
if (is_read)
*val = *reg;
else
*reg = *val;

return true;
}
return false;
}

bool pmu_msr_read(unsigned int msr, uint64_t *val, int *err)
{
if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
if (is_amd_pmu_msr(msr)) {
*val = native_read_msr_safe(msr, err);
if (!xen_amd_pmu_emulate(msr, val, 1))
*val = native_read_msr_safe(msr, err);
return true;
}
} else {
int type, index;

if (is_intel_pmu_msr(msr, &type, &index)) {
*val = native_read_msr_safe(msr, err);
if (!xen_intel_pmu_emulate(msr, val, type, index, 1))
*val = native_read_msr_safe(msr, err);
return true;
}
}
Expand All @@ -191,16 +305,20 @@ bool pmu_msr_read(unsigned int msr, uint64_t *val, int *err)

bool pmu_msr_write(unsigned int msr, uint32_t low, uint32_t high, int *err)
{
uint64_t val = ((uint64_t)high << 32) | low;

if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
if (is_amd_pmu_msr(msr)) {
*err = native_write_msr_safe(msr, low, high);
if (!xen_amd_pmu_emulate(msr, &val, 0))
*err = native_write_msr_safe(msr, low, high);
return true;
}
} else {
int type, index;

if (is_intel_pmu_msr(msr, &type, &index)) {
*err = native_write_msr_safe(msr, low, high);
if (!xen_intel_pmu_emulate(msr, &val, type, index, 0))
*err = native_write_msr_safe(msr, low, high);
return true;
}
}
Expand All @@ -210,24 +328,52 @@ bool pmu_msr_write(unsigned int msr, uint32_t low, uint32_t high, int *err)

static unsigned long long xen_amd_read_pmc(int counter)
{
uint32_t msr;
int err;
struct xen_pmu_amd_ctxt *ctxt;
uint64_t *counter_regs;
struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
uint8_t xenpmu_flags = get_xenpmu_flags();

if (!xenpmu_data || !(xenpmu_flags & XENPMU_IRQ_PROCESSING)) {
uint32_t msr;
int err;

msr = amd_counters_base + (counter * amd_msr_step);
return native_read_msr_safe(msr, &err);
msr = amd_counters_base + (counter * amd_msr_step);
return native_read_msr_safe(msr, &err);
}

ctxt = &xenpmu_data->pmu.c.amd;
counter_regs = field_offset(ctxt, counters);
return counter_regs[counter];
}

static unsigned long long xen_intel_read_pmc(int counter)
{
int err;
uint32_t msr;
struct xen_pmu_intel_ctxt *ctxt;
uint64_t *fixed_counters;
struct xen_pmu_cntr_pair *arch_cntr_pair;
struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
uint8_t xenpmu_flags = get_xenpmu_flags();

if (counter & (1<<INTEL_PMC_TYPE_SHIFT))
msr = MSR_CORE_PERF_FIXED_CTR0 + (counter & 0xffff);
else
msr = MSR_IA32_PERFCTR0 + counter;
if (!xenpmu_data || !(xenpmu_flags & XENPMU_IRQ_PROCESSING)) {
uint32_t msr;
int err;

return native_read_msr_safe(msr, &err);
if (counter & (1 << INTEL_PMC_TYPE_SHIFT))
msr = MSR_CORE_PERF_FIXED_CTR0 + (counter & 0xffff);
else
msr = MSR_IA32_PERFCTR0 + counter;

return native_read_msr_safe(msr, &err);
}

ctxt = &xenpmu_data->pmu.c.intel;
if (counter & (1 << INTEL_PMC_TYPE_SHIFT)) {
fixed_counters = field_offset(ctxt, fixed_counters);
return fixed_counters[counter & 0xffff];
}

arch_cntr_pair = field_offset(ctxt, arch_counters);
return arch_cntr_pair[counter].counter;
}

unsigned long long xen_read_pmc(int counter)
Expand All @@ -249,6 +395,10 @@ int pmu_apic_update(uint32_t val)
}

xenpmu_data->pmu.l.lapic_lvtpc = val;

if (get_xenpmu_flags() & XENPMU_IRQ_PROCESSING)
return 0;

ret = HYPERVISOR_xenpmu_op(XENPMU_lvtpc_set, NULL);

return ret;
Expand Down Expand Up @@ -329,29 +479,34 @@ irqreturn_t xen_pmu_irq_handler(int irq, void *dev_id)
int err, ret = IRQ_NONE;
struct pt_regs regs;
const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();
uint8_t xenpmu_flags = get_xenpmu_flags();

if (!xenpmu_data) {
pr_warn_once("%s: pmudata not initialized\n", __func__);
return ret;
}

err = HYPERVISOR_xenpmu_op(XENPMU_flush, NULL);
if (err) {
pr_warn_once("%s: failed hypercall, err: %d\n", __func__, err);
return ret;
}

this_cpu_ptr(&xenpmu_shared)->flags =
xenpmu_flags | XENPMU_IRQ_PROCESSING;
xen_convert_regs(&xenpmu_data->pmu.r.regs, &regs,
xenpmu_data->pmu.pmu_flags);
if (x86_pmu.handle_irq(&regs))
ret = IRQ_HANDLED;

/* Write out cached context to HW */
err = HYPERVISOR_xenpmu_op(XENPMU_flush, NULL);
this_cpu_ptr(&xenpmu_shared)->flags = xenpmu_flags;
if (err) {
pr_warn_once("%s: failed hypercall, err: %d\n", __func__, err);
return IRQ_NONE;
}

return ret;
}

bool is_xen_pmu(int cpu)
{
return (per_cpu(xenpmu_shared, cpu) != NULL);
return (get_xenpmu_data() != NULL);
}

void xen_pmu_init(int cpu)
Expand Down Expand Up @@ -381,7 +536,8 @@ void xen_pmu_init(int cpu)
if (err)
goto fail;

per_cpu(xenpmu_shared, cpu) = xenpmu_data;
per_cpu(xenpmu_shared, cpu).xenpmu_data = xenpmu_data;
per_cpu(xenpmu_shared, cpu).flags = 0;

if (cpu == 0) {
perf_register_guest_info_callbacks(&xen_guest_cbs);
Expand Down Expand Up @@ -409,6 +565,6 @@ void xen_pmu_finish(int cpu)

(void)HYPERVISOR_xenpmu_op(XENPMU_finish, &xp);

free_pages((unsigned long)per_cpu(xenpmu_shared, cpu), 0);
per_cpu(xenpmu_shared, cpu) = NULL;
free_pages((unsigned long)per_cpu(xenpmu_shared, cpu).xenpmu_data, 0);
per_cpu(xenpmu_shared, cpu).xenpmu_data = NULL;
}

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