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Commit 73e75b41 authored by Hollis Blanchard's avatar Hollis Blanchard Committed by Avi Kivity
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KVM: ppc: Implement in-kernel exit timing statistics 



Existing KVM statistics are either just counters (kvm_stat) reported for
KVM generally or trace based aproaches like kvm_trace.
For KVM on powerpc we had the need to track the timings of the different exit
types. While this could be achieved parsing data created with a kvm_trace
extension this adds too much overhead (at least on embedded PowerPC) slowing
down the workloads we wanted to measure.

Therefore this patch adds a in-kernel exit timing statistic to the powerpc kvm
code. These statistic is available per vm&vcpu under the kvm debugfs directory.
As this statistic is low, but still some overhead it can be enabled via a
.config entry and should be off by default.

Since this patch touched all powerpc kvm_stat code anyway this code is now
merged and simplified together with the exit timing statistic code (still
working with exit timing disabled in .config).

Signed-off-by: default avatarChristian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: default avatarHollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent c5fbdffb

arch/powerpc/include/asm/kvm_host.h

+56 −0
Original line number Diff line number Diff line
@@ -71,6 +71,49 @@ struct kvmppc_44x_tlbe { 
	u32 word2;

};



enum kvm_exit_types {

	MMIO_EXITS,

	DCR_EXITS,

	SIGNAL_EXITS,

	ITLB_REAL_MISS_EXITS,

	ITLB_VIRT_MISS_EXITS,

	DTLB_REAL_MISS_EXITS,

	DTLB_VIRT_MISS_EXITS,

	SYSCALL_EXITS,

	ISI_EXITS,

	DSI_EXITS,

	EMULATED_INST_EXITS,

	EMULATED_MTMSRWE_EXITS,

	EMULATED_WRTEE_EXITS,

	EMULATED_MTSPR_EXITS,

	EMULATED_MFSPR_EXITS,

	EMULATED_MTMSR_EXITS,

	EMULATED_MFMSR_EXITS,

	EMULATED_TLBSX_EXITS,

	EMULATED_TLBWE_EXITS,

	EMULATED_RFI_EXITS,

	DEC_EXITS,

	EXT_INTR_EXITS,

	HALT_WAKEUP,

	USR_PR_INST,

	FP_UNAVAIL,

	DEBUG_EXITS,

	TIMEINGUEST,

	__NUMBER_OF_KVM_EXIT_TYPES

};



#ifdef CONFIG_KVM_EXIT_TIMING

/* allow access to big endian 32bit upper/lower parts and 64bit var */

struct exit_timing {

	union {

		u64 tv64;

		struct {

			u32 tbu, tbl;

		} tv32;

	};

};

#endif



struct kvm_arch {

};
@@ -130,6 +173,19 @@ struct kvm_vcpu_arch { 
	u32 dbcr0;

	u32 dbcr1;



#ifdef CONFIG_KVM_EXIT_TIMING

	struct exit_timing timing_exit;

	struct exit_timing timing_last_enter;

	u32 last_exit_type;

	u32 timing_count_type[__NUMBER_OF_KVM_EXIT_TYPES];

	u64 timing_sum_duration[__NUMBER_OF_KVM_EXIT_TYPES];

	u64 timing_sum_quad_duration[__NUMBER_OF_KVM_EXIT_TYPES];

	u64 timing_min_duration[__NUMBER_OF_KVM_EXIT_TYPES];

	u64 timing_max_duration[__NUMBER_OF_KVM_EXIT_TYPES];

	u64 timing_last_exit;

	struct dentry *debugfs_exit_timing;

#endif



	u32 last_inst;

	ulong fault_dear;

	ulong fault_esr;

arch/powerpc/kernel/asm-offsets.c

+11 −0
Original line number Diff line number Diff line
@@ -383,5 +383,16 @@ int main(void) 
	DEFINE(PTE_T_LOG2, PTE_T_LOG2);

#endif



#ifdef CONFIG_KVM_EXIT_TIMING

	DEFINE(VCPU_TIMING_EXIT_TBU, offsetof(struct kvm_vcpu,

						arch.timing_exit.tv32.tbu));

	DEFINE(VCPU_TIMING_EXIT_TBL, offsetof(struct kvm_vcpu,

						arch.timing_exit.tv32.tbl));

	DEFINE(VCPU_TIMING_LAST_ENTER_TBU, offsetof(struct kvm_vcpu,

					arch.timing_last_enter.tv32.tbu));

	DEFINE(VCPU_TIMING_LAST_ENTER_TBL, offsetof(struct kvm_vcpu,

					arch.timing_last_enter.tv32.tbl));

#endif



	return 0;

}

arch/powerpc/kvm/44x_emulate.c

+10 −1
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <asm/dcr-regs.h>

#include <asm/disassemble.h>

#include <asm/kvm_44x.h>

#include "timing.h"



#include "booke.h"

#include "44x_tlb.h"
@@ -58,11 +59,11 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu, 
	int ws;



	switch (get_op(inst)) {



	case OP_RFI:

		switch (get_xop(inst)) {

		case XOP_RFI:

			kvmppc_emul_rfi(vcpu);

			kvmppc_set_exit_type(vcpu, EMULATED_RFI_EXITS);

			*advance = 0;

			break;
@@ -78,10 +79,12 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu, 
		case XOP_MFMSR:

			rt = get_rt(inst);

			vcpu->arch.gpr[rt] = vcpu->arch.msr;

			kvmppc_set_exit_type(vcpu, EMULATED_MFMSR_EXITS);

			break;



		case XOP_MTMSR:

			rs = get_rs(inst);

			kvmppc_set_exit_type(vcpu, EMULATED_MTMSR_EXITS);

			kvmppc_set_msr(vcpu, vcpu->arch.gpr[rs]);

			break;
@@ -89,11 +92,13 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu, 
			rs = get_rs(inst);

			vcpu->arch.msr = (vcpu->arch.msr & ~MSR_EE)

							 | (vcpu->arch.gpr[rs] & MSR_EE);

			kvmppc_set_exit_type(vcpu, EMULATED_WRTEE_EXITS);

			break;



		case XOP_WRTEEI:

			vcpu->arch.msr = (vcpu->arch.msr & ~MSR_EE)

							 | (inst & MSR_EE);

			kvmppc_set_exit_type(vcpu, EMULATED_WRTEE_EXITS);

			break;



		case XOP_MFDCR:
@@ -127,6 +132,7 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu, 
				run->dcr.is_write = 0;

				vcpu->arch.io_gpr = rt;

				vcpu->arch.dcr_needed = 1;

				account_exit(vcpu, DCR_EXITS);

				emulated = EMULATE_DO_DCR;

			}
@@ -146,6 +152,7 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu, 
				run->dcr.data = vcpu->arch.gpr[rs];

				run->dcr.is_write = 1;

				vcpu->arch.dcr_needed = 1;

				account_exit(vcpu, DCR_EXITS);

				emulated = EMULATE_DO_DCR;

			}
@@ -276,6 +283,7 @@ int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs) 
		return EMULATE_FAIL;

	}



	kvmppc_set_exit_type(vcpu, EMULATED_MTSPR_EXITS);

	return EMULATE_DONE;

}
@@ -357,6 +365,7 @@ int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt) 
		return EMULATE_FAIL;

	}



	kvmppc_set_exit_type(vcpu, EMULATED_MFSPR_EXITS);

	return EMULATE_DONE;

}

arch/powerpc/kvm/44x_tlb.c

+3 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <asm/mmu-44x.h>

#include <asm/kvm_ppc.h>

#include <asm/kvm_44x.h>

#include "timing.h"



#include "44x_tlb.h"
@@ -470,6 +471,7 @@ int kvmppc_44x_emul_tlbwe(struct kvm_vcpu *vcpu, u8 ra, u8 rs, u8 ws) 
	KVMTRACE_5D(GTLB_WRITE, vcpu, gtlb_index, tlbe->tid, tlbe->word0,

	            tlbe->word1, tlbe->word2, handler);



	kvmppc_set_exit_type(vcpu, EMULATED_TLBWE_EXITS);

	return EMULATE_DONE;

}
@@ -493,5 +495,6 @@ int kvmppc_44x_emul_tlbsx(struct kvm_vcpu *vcpu, u8 rt, u8 ra, u8 rb, u8 rc) 
	}

	vcpu->arch.gpr[rt] = gtlb_index;



	kvmppc_set_exit_type(vcpu, EMULATED_TLBSX_EXITS);

	return EMULATE_DONE;

}

arch/powerpc/kvm/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -32,6 +32,17 @@ config KVM_440 


	  If unsure, say N.



config KVM_EXIT_TIMING

	bool "Detailed exit timing"

	depends on KVM

	---help---

	  Calculate elapsed time for every exit/enter cycle. A per-vcpu

	  report is available in debugfs kvm/vm#_vcpu#_timing.

	  The overhead is relatively small, however it is not recommended for

	  production environments.



	  If unsure, say N.



config KVM_TRACE

	bool "KVM trace support"

	depends on KVM && MARKERS && SYSFS