Re: [PATCH v6 2/4] KVM: stats: Add fd-based API to read binary stats data

[Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>]

On 5/24/21 8:18 AM, Jing Zhang wrote:
> Provides a file descriptor per VM to read VM stats info/data.
> Provides a file descriptor per vCPU to read vCPU stats info/data.
>
> Reviewed-by: David Matlack<dmatlack@xxxxxxxxxx>
> Reviewed-by: Ricardo Koller<ricarkol@xxxxxxxxxx>
> Signed-off-by: Jing Zhang<jingzhangos@xxxxxxxxxx>
> ---
>   arch/arm64/kvm/guest.c    |  26 ++++++
>   arch/mips/kvm/mips.c      |  52 ++++++++++++
>   arch/powerpc/kvm/book3s.c |  52 ++++++++++++
>   arch/powerpc/kvm/booke.c  |  45 +++++++++++
>   arch/s390/kvm/kvm-s390.c  | 117 +++++++++++++++++++++++++++
>   arch/x86/kvm/x86.c        |  53 ++++++++++++
>   include/linux/kvm_host.h  | 132 ++++++++++++++++++++++++++++++
>   include/uapi/linux/kvm.h  |  50 ++++++++++++
>   virt/kvm/kvm_main.c       | 165 ++++++++++++++++++++++++++++++++++++++
>   9 files changed, 692 insertions(+)
>
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 0e41331b0911..1cc1d83630ac 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -28,6 +28,32 @@
>   
>   #include "trace.h"
>   
> +struct _kvm_stats_desc kvm_vm_stats_desc[] = DEFINE_VM_STATS_DESC();
> +
> +struct _kvm_stats_header kvm_vm_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vm_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vm_stats_desc),
> +};
> +
> +struct _kvm_stats_desc kvm_vcpu_stats_desc[] = DEFINE_VCPU_STATS_DESC(
> +	STATS_DESC_COUNTER("hvc_exit_stat"),
> +	STATS_DESC_COUNTER("wfe_exit_stat"),
> +	STATS_DESC_COUNTER("wfi_exit_stat"),
> +	STATS_DESC_COUNTER("mmio_exit_user"),
> +	STATS_DESC_COUNTER("mmio_exit_kernel"),
> +	STATS_DESC_COUNTER("exits"));
> +
> +struct _kvm_stats_header kvm_vcpu_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vcpu_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vcpu_stats_desc),
> +};
> +
>   struct kvm_stats_debugfs_item debugfs_entries[] = {
>   	VCPU_STAT_COM("halt_successful_poll", halt_successful_poll),
>   	VCPU_STAT_COM("halt_attempted_poll", halt_attempted_poll), diff --git a/arch/mips/kvm/mips.c 
> b/arch/mips/kvm/mips.c index f4fc60c05e9c..f17a65743ccd 100644 --- 
> a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -38,6 +38,58 @@ 
> #define VECTORSPACING 0x100 /* for EI/VI mode */ #endif +struct 
> _kvm_stats_desc kvm_vm_stats_desc[] = DEFINE_VM_STATS_DESC(); + 
> +struct _kvm_stats_header kvm_vm_stats_header = { + .name_size = 
> KVM_STATS_NAME_LEN, + .count = ARRAY_SIZE(kvm_vm_stats_desc), + 
> .desc_offset = sizeof(struct kvm_stats_header), + .data_offset = 
> sizeof(struct kvm_stats_header) + + sizeof(kvm_vm_stats_desc), +}; + 
> +struct _kvm_stats_desc kvm_vcpu_stats_desc[] = 
> DEFINE_VCPU_STATS_DESC( + STATS_DESC_COUNTER("wait_exits"),
> +	STATS_DESC_COUNTER("cache_exits"),
> +	STATS_DESC_COUNTER("signal_exits"),
> +	STATS_DESC_COUNTER("int_exits"),
> +	STATS_DESC_COUNTER("cop_unusable_exits"),
> +	STATS_DESC_COUNTER("tlbmod_exits"),
> +	STATS_DESC_COUNTER("tlbmiss_ld_exits"),
> +	STATS_DESC_COUNTER("tlbmiss_st_exits"),
> +	STATS_DESC_COUNTER("addrerr_st_exits"),
> +	STATS_DESC_COUNTER("addrerr_ld_exits"),
> +	STATS_DESC_COUNTER("syscall_exits"),
> +	STATS_DESC_COUNTER("resvd_inst_exits"),
> +	STATS_DESC_COUNTER("break_inst_exits"),
> +	STATS_DESC_COUNTER("trap_inst_exits"),
> +	STATS_DESC_COUNTER("msa_fpe_exits"),
> +	STATS_DESC_COUNTER("fpe_exits"),
> +	STATS_DESC_COUNTER("msa_disabled_exits"),
> +	STATS_DESC_COUNTER("flush_dcache_exits"),
> +#ifdef CONFIG_KVM_MIPS_VZ
> +	STATS_DESC_COUNTER("vz_gpsi_exits"),
> +	STATS_DESC_COUNTER("vz_gsfc_exits"),
> +	STATS_DESC_COUNTER("vz_hc_exits"),
> +	STATS_DESC_COUNTER("vz_grr_exits"),
> +	STATS_DESC_COUNTER("vz_gva_exits"),
> +	STATS_DESC_COUNTER("vz_ghfc_exits"),
> +	STATS_DESC_COUNTER("vz_gpa_exits"),
> +	STATS_DESC_COUNTER("vz_resvd_exits"),
> +#ifdef CONFIG_CPU_LOONGSON64
> +	STATS_DESC_COUNTER("vz_cpucfg_exits"),
> +#endif
> +#endif
> +	);
> +
> +struct _kvm_stats_header kvm_vcpu_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vcpu_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vcpu_stats_desc),
> +};
> +
>   struct kvm_stats_debugfs_item debugfs_entries[] = {
>   	VCPU_STAT("wait", wait_exits),
>   	VCPU_STAT("cache", cache_exits),
> diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
> index bd3a10e1fdaf..5e8ee0d39ef9 100644
> --- a/arch/powerpc/kvm/book3s.c
> +++ b/arch/powerpc/kvm/book3s.c
> @@ -38,6 +38,58 @@
>   
>   /* #define EXIT_DEBUG */
>   
> +struct _kvm_stats_desc kvm_vm_stats_desc[] = DEFINE_VM_STATS_DESC(
> +	STATS_DESC_ICOUNTER("num_2M_pages"),
> +	STATS_DESC_ICOUNTER("num_1G_pages"));
> +
> +struct _kvm_stats_header kvm_vm_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vm_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vm_stats_desc),
> +};
> +
> +struct _kvm_stats_desc kvm_vcpu_stats_desc[] = DEFINE_VCPU_STATS_DESC(
> +	STATS_DESC_COUNTER("sum_exits"),
> +	STATS_DESC_COUNTER("mmio_exits"),
> +	STATS_DESC_COUNTER("signal_exits"),
> +	STATS_DESC_COUNTER("light_exits"),
> +	STATS_DESC_COUNTER("itlb_real_miss_exits"),
> +	STATS_DESC_COUNTER("itlb_virt_miss_exits"),
> +	STATS_DESC_COUNTER("dtlb_real_miss_exits"),
> +	STATS_DESC_COUNTER("dtlb_virt_miss_exits"),
> +	STATS_DESC_COUNTER("syscall_exits"),
> +	STATS_DESC_COUNTER("isi_exits"),
> +	STATS_DESC_COUNTER("dsi_exits"),
> +	STATS_DESC_COUNTER("emulated_inst_exits"),
> +	STATS_DESC_COUNTER("dec_exits"),
> +	STATS_DESC_COUNTER("ext_intr_exits"),
> +	STATS_DESC_TIME_NSEC("halt_wait_ns"),
> +	STATS_DESC_COUNTER("halt_successful_wait"),
> +	STATS_DESC_COUNTER("dbell_exits"),
> +	STATS_DESC_COUNTER("gdbell_exits"),
> +	STATS_DESC_COUNTER("ld"),
> +	STATS_DESC_COUNTER("st"),
> +	STATS_DESC_COUNTER("pf_storage"),
> +	STATS_DESC_COUNTER("pf_instruc"),
> +	STATS_DESC_COUNTER("sp_storage"),
> +	STATS_DESC_COUNTER("sp_instruc"),
> +	STATS_DESC_COUNTER("queue_intr"),
> +	STATS_DESC_COUNTER("ld_slow"),
> +	STATS_DESC_COUNTER("st_slow"),
> +	STATS_DESC_COUNTER("pthru_all"),
> +	STATS_DESC_COUNTER("pthru_host"),
> +	STATS_DESC_COUNTER("pthru_bad_aff"));
> +
> +struct _kvm_stats_header kvm_vcpu_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vcpu_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vcpu_stats_desc),
> +};
> +
>   struct kvm_stats_debugfs_item debugfs_entries[] = {
>   	VCPU_STAT("exits", sum_exits),
>   	VCPU_STAT("mmio", mmio_exits),
> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
> index 07fdd7a1254a..86d221e9193e 100644
> --- a/arch/powerpc/kvm/booke.c
> +++ b/arch/powerpc/kvm/booke.c
> @@ -36,6 +36,51 @@
>   
>   unsigned long kvmppc_booke_handlers;
>   
> +struct _kvm_stats_desc kvm_vm_stats_desc[] = DEFINE_VM_STATS_DESC(
> +	STATS_DESC_ICOUNTER("num_2M_pages"),
> +	STATS_DESC_ICOUNTER("num_1G_pages"));
> +
> +struct _kvm_stats_header kvm_vm_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vm_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vm_stats_desc),
> +};
> +
> +struct _kvm_stats_desc kvm_vcpu_stats_desc[] = DEFINE_VCPU_STATS_DESC(
> +	STATS_DESC_COUNTER("sum_exits"),
> +	STATS_DESC_COUNTER("mmio_exits"),
> +	STATS_DESC_COUNTER("signal_exits"),
> +	STATS_DESC_COUNTER("light_exits"),
> +	STATS_DESC_COUNTER("itlb_real_miss_exits"),
> +	STATS_DESC_COUNTER("itlb_virt_miss_exits"),
> +	STATS_DESC_COUNTER("dtlb_real_miss_exits"),
> +	STATS_DESC_COUNTER("dtlb_virt_miss_exits"),
> +	STATS_DESC_COUNTER("syscall_exits"),
> +	STATS_DESC_COUNTER("isi_exits"),
> +	STATS_DESC_COUNTER("dsi_exits"),
> +	STATS_DESC_COUNTER("emulated_inst_exits"),
> +	STATS_DESC_COUNTER("dec_exits"),
> +	STATS_DESC_COUNTER("ext_intr_exits"),
> +	STATS_DESC_TIME_NSEC("halt_wait_ns"),
> +	STATS_DESC_COUNTER("halt_successful_wait"),
> +	STATS_DESC_COUNTER("dbell_exits"),
> +	STATS_DESC_COUNTER("gdbell_exits"),
> +	STATS_DESC_COUNTER("ld"),
> +	STATS_DESC_COUNTER("st"),
> +	STATS_DESC_COUNTER("pthru_all"),
> +	STATS_DESC_COUNTER("pthru_host"),
> +	STATS_DESC_COUNTER("pthru_bad_aff"));
> +
> +struct _kvm_stats_header kvm_vcpu_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vcpu_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vcpu_stats_desc),
> +};
> +
>   struct kvm_stats_debugfs_item debugfs_entries[] = {
>   	VCPU_STAT("mmio", mmio_exits),
>   	VCPU_STAT("sig", signal_exits),
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index d6bf3372bb10..003feee79fce 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -58,6 +58,123 @@
>   #define VCPU_IRQS_MAX_BUF (sizeof(struct kvm_s390_irq) * \
>   			   (KVM_MAX_VCPUS + LOCAL_IRQS))
>   
> +struct _kvm_stats_desc kvm_vm_stats_desc[] = DEFINE_VM_STATS_DESC(
> +	STATS_DESC_COUNTER("inject_io"),
> +	STATS_DESC_COUNTER("inject_float_mchk"),
> +	STATS_DESC_COUNTER("inject_pfault_done"),
> +	STATS_DESC_COUNTER("inject_service_signal"),
> +	STATS_DESC_COUNTER("inject_virtio"));
> +
> +struct _kvm_stats_header kvm_vm_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vm_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vm_stats_desc),
> +};
> +
> +struct _kvm_stats_desc kvm_vcpu_stats_desc[] = DEFINE_VCPU_STATS_DESC(
> +	STATS_DESC_COUNTER("exit_userspace"),
> +	STATS_DESC_COUNTER("exit_null"),
> +	STATS_DESC_COUNTER("exit_external_request"),
> +	STATS_DESC_COUNTER("exit_io_request"),
> +	STATS_DESC_COUNTER("exit_external_interrupt"),
> +	STATS_DESC_COUNTER("exit_stop_request"),
> +	STATS_DESC_COUNTER("exit_validity"),
> +	STATS_DESC_COUNTER("exit_instruction"),
> +	STATS_DESC_COUNTER("exit_pei"),
> +	STATS_DESC_COUNTER("halt_no_poll_steal"),
> +	STATS_DESC_COUNTER("instruction_lctl"),
> +	STATS_DESC_COUNTER("instruction_lctlg"),
> +	STATS_DESC_COUNTER("instruction_stctl"),
> +	STATS_DESC_COUNTER("instruction_stctg"),
> +	STATS_DESC_COUNTER("exit_program_interruption"),
> +	STATS_DESC_COUNTER("exit_instr_and_program"),
> +	STATS_DESC_COUNTER("exit_operation_exception"),
> +	STATS_DESC_COUNTER("deliver_ckc"),
> +	STATS_DESC_COUNTER("deliver_cputm"),
> +	STATS_DESC_COUNTER("deliver_external_call"),
> +	STATS_DESC_COUNTER("deliver_emergency_signal"),
> +	STATS_DESC_COUNTER("deliver_service_signal"),
> +	STATS_DESC_COUNTER("deliver_virtio"),
> +	STATS_DESC_COUNTER("deliver_stop_signal"),
> +	STATS_DESC_COUNTER("deliver_prefix_signal"),
> +	STATS_DESC_COUNTER("deliver_restart_signal"),
> +	STATS_DESC_COUNTER("deliver_program"),
> +	STATS_DESC_COUNTER("deliver_io"),
> +	STATS_DESC_COUNTER("deliver_machine_check"),
> +	STATS_DESC_COUNTER("exit_wait_state"),
> +	STATS_DESC_COUNTER("inject_ckc"),
> +	STATS_DESC_COUNTER("inject_cputm"),
> +	STATS_DESC_COUNTER("inject_external_call"),
> +	STATS_DESC_COUNTER("inject_emergency_signal"),
> +	STATS_DESC_COUNTER("inject_mchk"),
> +	STATS_DESC_COUNTER("inject_pfault_init"),
> +	STATS_DESC_COUNTER("inject_program"),
> +	STATS_DESC_COUNTER("inject_restart"),
> +	STATS_DESC_COUNTER("inject_set_prefix"),
> +	STATS_DESC_COUNTER("inject_stop_signal"),
> +	STATS_DESC_COUNTER("instruction_epsw"),
> +	STATS_DESC_COUNTER("instruction_gs"),
> +	STATS_DESC_COUNTER("instruction_io_other"),
> +	STATS_DESC_COUNTER("instruction_lpsw"),
> +	STATS_DESC_COUNTER("instruction_lpswe"),
> +	STATS_DESC_COUNTER("instruction_pfmf"),
> +	STATS_DESC_COUNTER("instruction_ptff"),
> +	STATS_DESC_COUNTER("instruction_sck"),
> +	STATS_DESC_COUNTER("instruction_sckpf"),
> +	STATS_DESC_COUNTER("instruction_stidp"),
> +	STATS_DESC_COUNTER("instruction_spx"),
> +	STATS_DESC_COUNTER("instruction_stpx"),
> +	STATS_DESC_COUNTER("instruction_stap"),
> +	STATS_DESC_COUNTER("instruction_iske"),
> +	STATS_DESC_COUNTER("instruction_ri"),
> +	STATS_DESC_COUNTER("instruction_rrbe"),
> +	STATS_DESC_COUNTER("instruction_sske"),
> +	STATS_DESC_COUNTER("instruction_ipte_interlock"),
> +	STATS_DESC_COUNTER("instruction_stsi"),
> +	STATS_DESC_COUNTER("instruction_stfl"),
> +	STATS_DESC_COUNTER("instruction_tb"),
> +	STATS_DESC_COUNTER("instruction_tpi"),
> +	STATS_DESC_COUNTER("instruction_tprot"),
> +	STATS_DESC_COUNTER("instruction_tsch"),
> +	STATS_DESC_COUNTER("instruction_sie"),
> +	STATS_DESC_COUNTER("instruction_essa"),
> +	STATS_DESC_COUNTER("instruction_sthyi"),
> +	STATS_DESC_COUNTER("instruction_sigp_sense"),
> +	STATS_DESC_COUNTER("instruction_sigp_sense_running"),
> +	STATS_DESC_COUNTER("instruction_sigp_external_call"),
> +	STATS_DESC_COUNTER("instruction_sigp_emergency"),
> +	STATS_DESC_COUNTER("instruction_sigp_cond_emergency"),
> +	STATS_DESC_COUNTER("instruction_sigp_start"),
> +	STATS_DESC_COUNTER("instruction_sigp_stop"),
> +	STATS_DESC_COUNTER("instruction_sigp_stop_store_status"),
> +	STATS_DESC_COUNTER("instruction_sigp_store_status"),
> +	STATS_DESC_COUNTER("instruction_sigp_store_adtl_status"),
> +	STATS_DESC_COUNTER("instruction_sigp_arch"),
> +	STATS_DESC_COUNTER("instruction_sigp_prefix"),
> +	STATS_DESC_COUNTER("instruction_sigp_restart"),
> +	STATS_DESC_COUNTER("instruction_sigp_init_cpu_reset"),
> +	STATS_DESC_COUNTER("instruction_sigp_cpu_reset"),
> +	STATS_DESC_COUNTER("instruction_sigp_unknown"),
> +	STATS_DESC_COUNTER("diagnose_10"),
> +	STATS_DESC_COUNTER("diagnose_44"),
> +	STATS_DESC_COUNTER("diagnose_9c"),
> +	STATS_DESC_COUNTER("diagnose_9c_ignored"),
> +	STATS_DESC_COUNTER("diagnose_258"),
> +	STATS_DESC_COUNTER("diagnose_308"),
> +	STATS_DESC_COUNTER("diagnose_500"),
> +	STATS_DESC_COUNTER("diagnose_other"),
> +	STATS_DESC_COUNTER("pfault_sync"));
> +
> +struct _kvm_stats_header kvm_vcpu_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vcpu_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vcpu_stats_desc),
> +};
> +
>   struct kvm_stats_debugfs_item debugfs_entries[] = {
>   	VCPU_STAT("userspace_handled", exit_userspace),
>   	VCPU_STAT("exit_null", exit_null),
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 9a93d80caff6..84880687c199 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -214,6 +214,59 @@ EXPORT_SYMBOL_GPL(host_xss);
>   u64 __read_mostly supported_xss;
>   EXPORT_SYMBOL_GPL(supported_xss);
>   
> +struct _kvm_stats_desc kvm_vm_stats_desc[] = DEFINE_VM_STATS_DESC(
> +	STATS_DESC_COUNTER("mmu_shadow_zapped"),
> +	STATS_DESC_COUNTER("mmu_pte_write"),
> +	STATS_DESC_COUNTER("mmu_pde_zapped"),
> +	STATS_DESC_COUNTER("mmu_flooded"),
> +	STATS_DESC_COUNTER("mmu_recycled"),
> +	STATS_DESC_COUNTER("mmu_cache_miss"),
> +	STATS_DESC_ICOUNTER("mmu_unsync"),
> +	STATS_DESC_ICOUNTER("largepages"),
> +	STATS_DESC_ICOUNTER("nx_largepages_splits"),
> +	STATS_DESC_ICOUNTER("max_mmu_page_hash_collisions"));
> +
> +struct _kvm_stats_header kvm_vm_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vm_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vm_stats_desc),
> +};
> +
> +struct _kvm_stats_desc kvm_vcpu_stats_desc[] = DEFINE_VCPU_STATS_DESC(
> +	STATS_DESC_COUNTER("pf_fixed"),
> +	STATS_DESC_COUNTER("pf_guest"),
> +	STATS_DESC_COUNTER("tlb_flush"),
> +	STATS_DESC_COUNTER("invlpg"),
> +	STATS_DESC_COUNTER("exits"),
> +	STATS_DESC_COUNTER("io_exits"),
> +	STATS_DESC_COUNTER("mmio_exits"),
> +	STATS_DESC_COUNTER("signal_exits"),
> +	STATS_DESC_COUNTER("irq_window_exits"),
> +	STATS_DESC_COUNTER("nmi_window_exits"),
> +	STATS_DESC_COUNTER("l1d_flush"),
> +	STATS_DESC_COUNTER("halt_exits"),
> +	STATS_DESC_COUNTER("request_irq_exits"),
> +	STATS_DESC_COUNTER("irq_exits"),
> +	STATS_DESC_COUNTER("host_state_reload"),
> +	STATS_DESC_COUNTER("fpu_reload"),
> +	STATS_DESC_COUNTER("insn_emulation"),
> +	STATS_DESC_COUNTER("insn_emulation_fail"),
> +	STATS_DESC_COUNTER("hypercalls"),
> +	STATS_DESC_COUNTER("irq_injections"),
> +	STATS_DESC_COUNTER("nmi_injections"),
> +	STATS_DESC_COUNTER("req_event"),
> +	STATS_DESC_COUNTER("nested_run"));
> +
> +struct _kvm_stats_header kvm_vcpu_stats_header = {
> +	.name_size = KVM_STATS_NAME_LEN,
> +	.count = ARRAY_SIZE(kvm_vcpu_stats_desc),
> +	.desc_offset = sizeof(struct kvm_stats_header),
> +	.data_offset = sizeof(struct kvm_stats_header) +
> +		sizeof(kvm_vcpu_stats_desc),
> +};
> +
>   struct kvm_stats_debugfs_item debugfs_entries[] = {
>   	VCPU_STAT("pf_fixed", pf_fixed),
>   	VCPU_STAT("pf_guest", pf_guest),
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 97700e41db3b..c0a8e6ddc745 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1240,6 +1240,19 @@ struct kvm_stats_debugfs_item {
>   	int mode;
>   };
>   
> +struct _kvm_stats_header {
> +	__u32 name_size;
> +	__u32 count;
> +	__u32 desc_offset;
> +	__u32 data_offset;
> +};
> +
> +#define KVM_STATS_NAME_LEN	48
> +struct _kvm_stats_desc {
> +	struct kvm_stats_desc desc;
> +	char name[KVM_STATS_NAME_LEN];
> +};
> +
>   #define KVM_DBGFS_GET_MODE(dbgfs_item)                                         \
>   	((dbgfs_item)->mode ? (dbgfs_item)->mode : 0644)
>   
> @@ -1253,8 +1266,127 @@ struct kvm_stats_debugfs_item {
>   	{ n, offsetof(struct kvm_vcpu, stat.common.x),			       \
>   	  KVM_STAT_VCPU, ## __VA_ARGS__ }
>   
> +#define STATS_DESC(stat, type, unit, scale, exp)			       \
> +	{								       \
> +		{							       \
> +			.flags = type | unit | scale,			       \
> +			.exponent = exp,				       \
> +			.size = 1					       \
> +		},							       \
> +		.name = stat,						       \
> +	}
> +#define STATS_DESC_CUMULATIVE(name, unit, scale, exponent)		       \
> +	STATS_DESC(name, KVM_STATS_TYPE_CUMULATIVE, unit, scale, exponent)
> +#define STATS_DESC_INSTANT(name, unit, scale, exponent)			       \
> +	STATS_DESC(name, KVM_STATS_TYPE_INSTANT, unit, scale, exponent)
> +
> +/* Cumulative counter */
> +#define STATS_DESC_COUNTER(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_NONE,		       \
> +		KVM_STATS_BASE_POW10, 0)
> +/* Instantaneous counter */
> +#define STATS_DESC_ICOUNTER(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_NONE,			       \
> +		KVM_STATS_BASE_POW10, 0)
> +
> +/* Cumulative clock cycles */
> +#define STATS_DESC_CYCLE(name)						       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_CYCLES,		       \
> +		KVM_STATS_BASE_POW10, 0)
> +/* Instantaneous clock cycles */
> +#define STATS_DESC_ICYCLE(name)						       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_CYCLES,			       \
> +		KVM_STATS_BASE_POW10, 0)
> +
> +/* Cumulative memory size in Byte */
> +#define STATS_DESC_SIZE_BYTE(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_BYTES,		       \
> +		KVM_STATS_BASE_POW2, 0)
> +/* Cumulative memory size in KiByte */
> +#define STATS_DESC_SIZE_KBYTE(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_BYTES,		       \
> +		KVM_STATS_BASE_POW2, 10)
> +/* Cumulative memory size in MiByte */
> +#define STATS_DESC_SIZE_MBYTE(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_BYTES,		       \
> +		KVM_STATS_BASE_POW2, 20)
> +/* Cumulative memory size in GiByte */
> +#define STATS_DESC_SIZE_GBYTE(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_BYTES,		       \
> +		KVM_STATS_BASE_POW2, 30)
> +
> +/* Instantaneous memory size in Byte */
> +#define STATS_DESC_ISIZE_BYTE(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_BYTES,			       \
> +		KVM_STATS_BASE_POW2, 0)
> +/* Instantaneous memory size in KiByte */
> +#define STATS_DESC_ISIZE_KBYTE(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_BYTES,			       \
> +		KVM_STATS_BASE_POW2, 10)
> +/* Instantaneous memory size in MiByte */
> +#define STATS_DESC_ISIZE_MBYTE(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_BYTES,			       \
> +		KVM_STATS_BASE_POW2, 20)
> +/* Instantaneous memory size in GiByte */
> +#define STATS_DESC_ISIZE_GBYTE(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_BYTES,			       \
> +		KVM_STATS_BASE_POW2, 30)
> +
> +/* Cumulative time in second */
> +#define STATS_DESC_TIME_SEC(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_SECONDS,		       \
> +		KVM_STATS_BASE_POW10, 0)
> +/* Cumulative time in millisecond */
> +#define STATS_DESC_TIME_MSEC(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_SECONDS,		       \
> +		KVM_STATS_BASE_POW10, -3)
> +/* Cumulative time in microsecond */
> +#define STATS_DESC_TIME_USEC(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_SECONDS,		       \
> +		KVM_STATS_BASE_POW10, -6)
> +/* Cumulative time in nanosecond */
> +#define STATS_DESC_TIME_NSEC(name)					       \
> +	STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_SECONDS,		       \
> +		KVM_STATS_BASE_POW10, -9)
> +
> +/* Instantaneous time in second */
> +#define STATS_DESC_ITIME_SEC(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_SECONDS,		       \
> +		KVM_STATS_BASE_POW10, 0)
> +/* Instantaneous time in millisecond */
> +#define STATS_DESC_ITIME_MSEC(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_SECONDS,		       \
> +		KVM_STATS_BASE_POW10, -3)
> +/* Instantaneous time in microsecond */
> +#define STATS_DESC_ITIME_USEC(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_SECONDS,		       \
> +		KVM_STATS_BASE_POW10, -6)
> +/* Instantaneous time in nanosecond */
> +#define STATS_DESC_ITIME_NSEC(name)					       \
> +	STATS_DESC_INSTANT(name, KVM_STATS_UNIT_SECONDS,		       \
> +		KVM_STATS_BASE_POW10, -9)
> +
> +#define DEFINE_VM_STATS_DESC(...) {					       \
> +	STATS_DESC_COUNTER("remote_tlb_flush"),				       \
> +	## __VA_ARGS__							       \
> +}
> +
> +#define DEFINE_VCPU_STATS_DESC(...) {					       \
> +	STATS_DESC_COUNTER("halt_successful_poll"),			       \
> +	STATS_DESC_COUNTER("halt_attempted_poll"),			       \
> +	STATS_DESC_COUNTER("halt_poll_invalid"),			       \
> +	STATS_DESC_COUNTER("halt_wakeup"),				       \
> +	STATS_DESC_TIME_NSEC("halt_poll_success_ns"),			       \
> +	STATS_DESC_TIME_NSEC("halt_poll_fail_ns"),			       \
> +	## __VA_ARGS__							       \
> +}
> +
>   extern struct kvm_stats_debugfs_item debugfs_entries[];
>   extern struct dentry *kvm_debugfs_dir;
> +extern struct _kvm_stats_header kvm_vm_stats_header;
> +extern struct _kvm_stats_header kvm_vcpu_stats_header;
> +extern struct _kvm_stats_desc kvm_vm_stats_desc[];
> +extern struct _kvm_stats_desc kvm_vcpu_stats_desc[];
>   
>   #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
>   static inline int mmu_notifier_retry(struct kvm *kvm, unsigned long mmu_seq)
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 3fd9a7e9d90c..82db825c392c 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1082,6 +1082,7 @@ struct kvm_ppc_resize_hpt {
>   #define KVM_CAP_SGX_ATTRIBUTE 196
>   #define KVM_CAP_VM_COPY_ENC_CONTEXT_FROM 197
>   #define KVM_CAP_PTP_KVM 198
> +#define KVM_CAP_STATS_BINARY_FD 199
>   
>   #ifdef KVM_CAP_IRQ_ROUTING
>   
> @@ -1898,4 +1899,53 @@ struct kvm_dirty_gfn {
>   #define KVM_BUS_LOCK_DETECTION_OFF             (1 << 0)
>   #define KVM_BUS_LOCK_DETECTION_EXIT            (1 << 1)
>   
> +#define KVM_STATS_ID_MAXLEN		64
> +
> +struct kvm_stats_header {
> +	char id[KVM_STATS_ID_MAXLEN];
> +	__u32 name_size;
> +	__u32 count;
> +	__u32 desc_offset;
> +	__u32 data_offset;
> +};
> +
> +#define KVM_STATS_TYPE_SHIFT		0
> +#define KVM_STATS_TYPE_MASK		(0xF << KVM_STATS_TYPE_SHIFT)
> +#define KVM_STATS_TYPE_CUMULATIVE	(0x0 << KVM_STATS_TYPE_SHIFT)
> +#define KVM_STATS_TYPE_INSTANT		(0x1 << KVM_STATS_TYPE_SHIFT)
> +#define KVM_STATS_TYPE_MAX		KVM_STATS_TYPE_INSTANT
> +
> +#define KVM_STATS_UNIT_SHIFT		4
> +#define KVM_STATS_UNIT_MASK		(0xF << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_NONE		(0x0 << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_BYTES		(0x1 << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_SECONDS		(0x2 << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_CYCLES		(0x3 << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_MAX		KVM_STATS_UNIT_CYCLES
> +
> +#define KVM_STATS_BASE_SHIFT		8
> +#define KVM_STATS_BASE_MASK		(0xF << KVM_STATS_BASE_SHIFT)
> +#define KVM_STATS_BASE_POW10		(0x0 << KVM_STATS_BASE_SHIFT)
> +#define KVM_STATS_BASE_POW2		(0x1 << KVM_STATS_BASE_SHIFT)
> +#define KVM_STATS_BASE_MAX		KVM_STATS_BASE_POW2
> +
> +struct kvm_stats_desc {
> +	__u32 flags;
> +	__s16 exponent;
> +	__u16 size;
> +	__u32 unused1;
> +	__u32 unused2;
> +	char name[0];
> +};
> +
> +struct kvm_vm_stats_data {
> +	unsigned long value[0];
> +};
> +
> +struct kvm_vcpu_stats_data {
> +	__u64 value[0];
> +};
> +
> +#define KVM_STATS_GETFD  _IOR(KVMIO,  0xcc, struct kvm_stats_header)
> +
>   #endif /* __LINUX_KVM_H */
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 34a4cf265297..9e20e2ff78b4 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3409,6 +3409,120 @@ static int kvm_vcpu_ioctl_set_sigmask(struct kvm_vcpu *vcpu, sigset_t *sigset)
>   	return 0;
>   }
>   
> +static ssize_t kvm_stats_read(char *id, struct _kvm_stats_header *header,
> +		struct _kvm_stats_desc *desc, void *stats, size_t size_stats,
> +		char __user *user_buffer, size_t size, loff_t *offset)
> +{
> +	ssize_t copylen, len, remain = size;
> +	size_t size_header, size_desc;
> +	loff_t pos = *offset;
> +	char __user *dest = user_buffer;
> +	void *src;
> +
> +	size_header = sizeof(*header);
> +	size_desc = header->count * sizeof(*desc);
> +
> +	len = KVM_STATS_ID_MAXLEN + size_header + size_desc + size_stats - pos;
> +	len = min(len, remain);
> +	if (len <= 0)
> +		return 0;
> +	remain = len;
> +
> +	/* Copy kvm stats header id string */
> +	copylen = KVM_STATS_ID_MAXLEN - pos;
> +	copylen = min(copylen, remain);
> +	if (copylen > 0) {
> +		src = id + pos;
> +		if (copy_to_user(dest, src, copylen))
> +			return -EFAULT;
> +		remain -= copylen;
> +		pos += copylen;
> +		dest += copylen;
> +	}
> +	/* Copy kvm stats header */
> +	copylen = KVM_STATS_ID_MAXLEN + size_header - pos;
> +	copylen = min(copylen, remain);
> +	if (copylen > 0) {
> +		src = header + pos - KVM_STATS_ID_MAXLEN;
> +		if (copy_to_user(dest, src, copylen))
> +			return -EFAULT;
> +		remain -= copylen;
> +		pos += copylen;
> +		dest += copylen;
> +	}
> +	/* Copy kvm stats descriptors */
> +	copylen = header->desc_offset + size_desc - pos;
> +	copylen = min(copylen, remain);
> +	if (copylen > 0) {
> +		src = desc + pos - header->desc_offset;
> +		if (copy_to_user(dest, src, copylen))
> +			return -EFAULT;
> +		remain -= copylen;
> +		pos += copylen;
> +		dest += copylen;
> +	}
> +	/* Copy kvm stats values */
> +	copylen = header->data_offset + size_stats - pos;
> +	copylen = min(copylen, remain);
> +	if (copylen > 0) {
> +		src = stats + pos - header->data_offset;
> +		if (copy_to_user(dest, src, copylen))
> +			return -EFAULT;
> +		remain -= copylen;
> +		pos += copylen;
> +		dest += copylen;
> +	}
> +


Is it possible to re-use the 'if' portion either via a separate function 
? For example,

static int copy_data(void *src)

{
        if (copy_to_user(dest, src, copylen))
            return -EFAULT;
        remain -= copylen;
        pos += copylen;
        dest += copylen;
        return 0;

}

and then calling it as,

        if (copylen > 0)

            copy_data(stats + pos - header->data_offset);

> +	*offset = pos;
> +	return len;
> +}
> +
> +static ssize_t kvm_vcpu_stats_read(struct file *file, char __user *user_buffer,
> +			      size_t size, loff_t *offset)
> +{
> +	char id[KVM_STATS_ID_MAXLEN];
> +	struct kvm_vcpu *vcpu = file->private_data;
> +
> +	snprintf(id, sizeof(id), "kvm-%d/vcpu-%d",
> +			task_pid_nr(current), vcpu->vcpu_id);
> +	return kvm_stats_read(id, &kvm_vcpu_stats_header,
> +			&kvm_vcpu_stats_desc[0], &vcpu->stat,
> +			sizeof(vcpu->stat), user_buffer, size, offset);
> +}
> +
> +static const struct file_operations kvm_vcpu_stats_fops = {
> +	.read = kvm_vcpu_stats_read,
> +	.llseek = noop_llseek,
> +};
> +
> +static int kvm_vcpu_ioctl_get_statsfd(struct kvm_vcpu *vcpu)
> +{
> +	int error, fd;
> +	struct file *file;
> +	char name[15 + ITOA_MAX_LEN + 1];
> +
> +	snprintf(name, sizeof(name), "kvm-vcpu-stats:%d", vcpu->vcpu_id);
> +
> +	error = get_unused_fd_flags(O_CLOEXEC);
> +	if (error < 0)
> +		return error;
> +	fd = error;
> +
> +	file = anon_inode_getfile(name, &kvm_vcpu_stats_fops, vcpu, O_RDONLY);
> +	if (IS_ERR(file)) {
> +		error = PTR_ERR(file);
> +		goto err_put_unused_fd;
> +	}
> +	file->f_mode |= FMODE_PREAD;
> +	fd_install(fd, file);
> +
> +	return fd;
> +
> +err_put_unused_fd:
> +	put_unused_fd(fd);
> +	return error;
> +}
> +
>   static long kvm_vcpu_ioctl(struct file *filp,
>   			   unsigned int ioctl, unsigned long arg)
>   {
> @@ -3606,6 +3720,10 @@ static long kvm_vcpu_ioctl(struct file *filp,
>   		r = kvm_arch_vcpu_ioctl_set_fpu(vcpu, fpu);
>   		break;
>   	}
> +	case KVM_STATS_GETFD: {
> +		r = kvm_vcpu_ioctl_get_statsfd(vcpu);
> +		break;
> +	}
>   	default:
>   		r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
>   	}
> @@ -3864,6 +3982,8 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
>   #else
>   		return 0;
>   #endif
> +	case KVM_CAP_STATS_BINARY_FD:
> +		return 1;
>   	default:
>   		break;
>   	}
> @@ -3967,6 +4087,48 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm,
>   	}
>   }
>   
> +static ssize_t kvm_vm_stats_read(struct file *file, char __user *user_buffer,
> +			      size_t size, loff_t *offset)
> +{
> +	char id[KVM_STATS_ID_MAXLEN];
> +	struct kvm *kvm = file->private_data;
> +
> +	snprintf(id, sizeof(id), "kvm-%d", task_pid_nr(current));
> +	return kvm_stats_read(id, &kvm_vm_stats_header, &kvm_vm_stats_desc[0],
> +		&kvm->stat, sizeof(kvm->stat), user_buffer, size, offset);
> +}
> +
> +static const struct file_operations kvm_vm_stats_fops = {
> +	.read = kvm_vm_stats_read,
> +	.llseek = noop_llseek,
> +};
> +
> +static int kvm_vm_ioctl_get_statsfd(struct kvm *kvm)
> +{
> +	int error, fd;
> +	struct file *file;
> +
> +	error = get_unused_fd_flags(O_CLOEXEC);
> +	if (error < 0)
> +		return error;
> +	fd = error;


Why not just do,

            fd = get_unused_fd_flags(O_CLOEXEC);
            if (fd < 0)
                    return fd;

?

> +
> +	file = anon_inode_getfile("kvm-vm-stats",
> +			&kvm_vm_stats_fops, kvm, O_RDONLY);
> +	if (IS_ERR(file)) {
> +		error = PTR_ERR(file);
> +		goto err_put_unused_fd;


Here, we can do,

               if (IS_ERR(file)) {

                    put_unused_fd(fd);

                    return (PTR_ERR(file));

                }

and won't need a goto statement.

Same comment for kvm_vcpu_ioctl_get_statsfd().

> +	}
> +	file->f_mode |= FMODE_PREAD;
> +	fd_install(fd, file);
> +
> +	return fd;
> +
> +err_put_unused_fd:
> +	put_unused_fd(fd);
> +	return error;
> +}
> +
>   static long kvm_vm_ioctl(struct file *filp,
>   			   unsigned int ioctl, unsigned long arg)
>   {
> @@ -4149,6 +4311,9 @@ static long kvm_vm_ioctl(struct file *filp,
>   	case KVM_RESET_DIRTY_RINGS:
>   		r = kvm_vm_ioctl_reset_dirty_pages(kvm);
>   		break;
> +	case KVM_STATS_GETFD:


This should be named KVM_GET_STATS_FD.  For example, we have names like 
KVM_GET_DIRTY_LOG etc.

Same comment for KVM_STATS_GETFD.

> +		r = kvm_vm_ioctl_get_statsfd(kvm);


It's probably more readable if we call it kvm_vm_ioctl_get_stats_fd().

> +		break;
>   	default:
>   		r = kvm_arch_vm_ioctl(filp, ioctl, arg);
>   	}