linux_kernel/arch/x86/xen/pmu.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/types.h>
#include <linux/interrupt.h>

#include <asm/xen/hypercall.h>
#include <xen/xen.h>
#include <xen/page.h>
#include <xen/interface/xen.h>
#include <xen/interface/vcpu.h>
#include <xen/interface/xenpmu.h>

#include "xen-ops.h"
#include "pmu.h"

/* x86_pmu.handle_irq definition */
#include "../events/perf_event.h"

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

	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
#define F10H_NUM_COUNTERS   4

static __read_mostly uint32_t amd_counters_base;
static __read_mostly uint32_t amd_ctrls_base;
static __read_mostly int amd_msr_step;
static __read_mostly int k7_counters_mirrored;
static __read_mostly int amd_num_counters;

/* Intel PMU */
#define MSR_TYPE_COUNTER            0
#define MSR_TYPE_CTRL               1
#define MSR_TYPE_GLOBAL             2
#define MSR_TYPE_ARCH_COUNTER       3
#define MSR_TYPE_ARCH_CTRL          4

/* Number of general pmu registers (CPUID.EAX[0xa].EAX[8..15]) */
#define PMU_GENERAL_NR_SHIFT        8
#define PMU_GENERAL_NR_BITS         8
#define PMU_GENERAL_NR_MASK         (((1 << PMU_GENERAL_NR_BITS) - 1) \
				     << PMU_GENERAL_NR_SHIFT)

/* Number of fixed pmu registers (CPUID.EDX[0xa].EDX[0..4]) */
#define PMU_FIXED_NR_SHIFT          0
#define PMU_FIXED_NR_BITS           5
#define PMU_FIXED_NR_MASK           (((1 << PMU_FIXED_NR_BITS) - 1) \
				     << PMU_FIXED_NR_SHIFT)

/* Alias registers (0x4c1) for full-width writes to PMCs */
#define MSR_PMC_ALIAS_MASK          (~(MSR_IA32_PERFCTR0 ^ MSR_IA32_PMC0))

#define INTEL_PMC_TYPE_SHIFT        30

static __read_mostly int intel_num_arch_counters, intel_num_fixed_counters;


static void xen_pmu_arch_init(void)
{
	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {

		switch (boot_cpu_data.x86) {
		case 0x15:
			amd_num_counters = F15H_NUM_COUNTERS;
			amd_counters_base = MSR_F15H_PERF_CTR;
			amd_ctrls_base = MSR_F15H_PERF_CTL;
			amd_msr_step = 2;
			k7_counters_mirrored = 1;
			break;
		case 0x10:
		case 0x12:
		case 0x14:
		case 0x16:
		default:
			amd_num_counters = F10H_NUM_COUNTERS;
			amd_counters_base = MSR_K7_PERFCTR0;
			amd_ctrls_base = MSR_K7_EVNTSEL0;
			amd_msr_step = 1;
			k7_counters_mirrored = 0;
			break;
		}
	} else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
		amd_num_counters = F10H_NUM_COUNTERS;
		amd_counters_base = MSR_K7_PERFCTR0;
		amd_ctrls_base = MSR_K7_EVNTSEL0;
		amd_msr_step = 1;
		k7_counters_mirrored = 0;
	} else {
		uint32_t eax, ebx, ecx, edx;

		cpuid(0xa, &eax, &ebx, &ecx, &edx);

		intel_num_arch_counters = (eax & PMU_GENERAL_NR_MASK) >>
			PMU_GENERAL_NR_SHIFT;
		intel_num_fixed_counters = (edx & PMU_FIXED_NR_MASK) >>
			PMU_FIXED_NR_SHIFT;
	}
}

static inline uint32_t get_fam15h_addr(u32 addr)
{
	switch (addr) {
	case MSR_K7_PERFCTR0:
	case MSR_K7_PERFCTR1:
	case MSR_K7_PERFCTR2:
	case MSR_K7_PERFCTR3:
		return MSR_F15H_PERF_CTR + (addr - MSR_K7_PERFCTR0);
	case MSR_K7_EVNTSEL0:
	case MSR_K7_EVNTSEL1:
	case MSR_K7_EVNTSEL2:
	case MSR_K7_EVNTSEL3:
		return MSR_F15H_PERF_CTL + (addr - MSR_K7_EVNTSEL0);
	default:
		break;
	}

	return addr;
}

static inline bool is_amd_pmu_msr(unsigned int msr)
{
	if ((msr >= MSR_F15H_PERF_CTL &&
	     msr < MSR_F15H_PERF_CTR + (amd_num_counters * 2)) ||
	    (msr >= MSR_K7_EVNTSEL0 &&
	     msr < MSR_K7_PERFCTR0 + amd_num_counters))
		return true;

	return false;
}

static int is_intel_pmu_msr(u32 msr_index, int *type, int *index)
{
	u32 msr_index_pmc;

	switch (msr_index) {
	case MSR_CORE_PERF_FIXED_CTR_CTRL:
	case MSR_IA32_DS_AREA:
	case MSR_IA32_PEBS_ENABLE:
		*type = MSR_TYPE_CTRL;
		return true;

	case MSR_CORE_PERF_GLOBAL_CTRL:
	case MSR_CORE_PERF_GLOBAL_STATUS:
	case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
		*type = MSR_TYPE_GLOBAL;
		return true;

	default:

		if ((msr_index >= MSR_CORE_PERF_FIXED_CTR0) &&
		    (msr_index < MSR_CORE_PERF_FIXED_CTR0 +
				 intel_num_fixed_counters)) {
			*index = msr_index - MSR_CORE_PERF_FIXED_CTR0;
			*type = MSR_TYPE_COUNTER;
			return true;
		}

		if ((msr_index >= MSR_P6_EVNTSEL0) &&
		    (msr_index < MSR_P6_EVNTSEL0 +  intel_num_arch_counters)) {
			*index = msr_index - MSR_P6_EVNTSEL0;
			*type = MSR_TYPE_ARCH_CTRL;
			return true;
		}

		msr_index_pmc = msr_index & MSR_PMC_ALIAS_MASK;
		if ((msr_index_pmc >= MSR_IA32_PERFCTR0) &&
		    (msr_index_pmc < MSR_IA32_PERFCTR0 +
				     intel_num_arch_counters)) {
			*type = MSR_TYPE_ARCH_COUNTER;
			*index = msr_index_pmc - MSR_IA32_PERFCTR0;
			return true;
		}
		return false;
	}
}

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_INTEL) {
		if (is_amd_pmu_msr(msr)) {
			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)) {
			if (!xen_intel_pmu_emulate(msr, val, type, index, 1))
				*val = native_read_msr_safe(msr, err);
			return true;
		}
	}

	return false;
}

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_INTEL) {
		if (is_amd_pmu_msr(msr)) {
			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)) {
			if (!xen_intel_pmu_emulate(msr, &val, type, index, 0))
				*err = native_write_msr_safe(msr, low, high);
			return true;
		}
	}

	return false;
}

static unsigned long long xen_amd_read_pmc(int counter)
{
	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);
	}

	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)
{
	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 (!xenpmu_data || !(xenpmu_flags & XENPMU_IRQ_PROCESSING)) {
		uint32_t msr;
		int 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)
{
	if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
		return xen_amd_read_pmc(counter);
	else
		return xen_intel_read_pmc(counter);
}

int pmu_apic_update(uint32_t val)
{
	int ret;
	struct xen_pmu_data *xenpmu_data = get_xenpmu_data();

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

	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;
}

/* perf callbacks */
static int xen_is_in_guest(void)
{
	const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();

	if (!xenpmu_data) {
		pr_warn_once("%s: pmudata not initialized\n", __func__);
		return 0;
	}

	if (!xen_initial_domain() || (xenpmu_data->domain_id >= DOMID_SELF))
		return 0;

	return 1;
}

static int xen_is_user_mode(void)
{
	const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();

	if (!xenpmu_data) {
		pr_warn_once("%s: pmudata not initialized\n", __func__);
		return 0;
	}

	if (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_PV)
		return (xenpmu_data->pmu.pmu_flags & PMU_SAMPLE_USER);
	else
		return !!(xenpmu_data->pmu.r.regs.cpl & 3);
}

static unsigned long xen_get_guest_ip(void)
{
	const struct xen_pmu_data *xenpmu_data = get_xenpmu_data();

	if (!xenpmu_data) {
		pr_warn_once("%s: pmudata not initialized\n", __func__);
		return 0;
	}

	return xenpmu_data->pmu.r.regs.ip;
}

static struct perf_guest_info_callbacks xen_guest_cbs = {
	.is_in_guest            = xen_is_in_guest,
	.is_user_mode           = xen_is_user_mode,
	.get_guest_ip           = xen_get_guest_ip,
};

/* Convert registers from Xen's format to Linux' */
static void xen_convert_regs(const struct xen_pmu_regs *xen_regs,
			     struct pt_regs *regs, uint64_t pmu_flags)
{
	regs->ip = xen_regs->ip;
	regs->cs = xen_regs->cs;
	regs->sp = xen_regs->sp;

	if (pmu_flags & PMU_SAMPLE_PV) {
		if (pmu_flags & PMU_SAMPLE_USER)
			regs->cs |= 3;
		else
			regs->cs &= ~3;
	} else {
		if (xen_regs->cpl)
			regs->cs |= 3;
		else
			regs->cs &= ~3;
	}
}

irqreturn_t xen_pmu_irq_handler(int irq, void *dev_id)
{
	int err, ret = IRQ_NONE;
	struct pt_regs regs = {0};
	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;
	}

	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 (get_xenpmu_data() != NULL);
}

void xen_pmu_init(int cpu)
{
	int err;
	struct xen_pmu_params xp;
	unsigned long pfn;
	struct xen_pmu_data *xenpmu_data;

	BUILD_BUG_ON(sizeof(struct xen_pmu_data) > PAGE_SIZE);

	if (xen_hvm_domain())
		return;

	xenpmu_data = (struct xen_pmu_data *)get_zeroed_page(GFP_KERNEL);
	if (!xenpmu_data) {
		pr_err("VPMU init: No memory\n");
		return;
	}
	pfn = virt_to_pfn(xenpmu_data);

	xp.val = pfn_to_mfn(pfn);
	xp.vcpu = cpu;
	xp.version.maj = XENPMU_VER_MAJ;
	xp.version.min = XENPMU_VER_MIN;
	err = HYPERVISOR_xenpmu_op(XENPMU_init, &xp);
	if (err)
		goto fail;

	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);
		xen_pmu_arch_init();
	}

	return;

fail:
	if (err == -EOPNOTSUPP || err == -ENOSYS)
		pr_info_once("VPMU disabled by hypervisor.\n");
	else
		pr_info_once("Could not initialize VPMU for cpu %d, error %d\n",
			cpu, err);
	free_pages((unsigned long)xenpmu_data, 0);
}

void xen_pmu_finish(int cpu)
{
	struct xen_pmu_params xp;

	if (xen_hvm_domain())
		return;

	xp.vcpu = cpu;
	xp.version.maj = XENPMU_VER_MAJ;
	xp.version.min = XENPMU_VER_MIN;

	(void)HYPERVISOR_xenpmu_op(XENPMU_finish, &xp);

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