7 files changed, 346 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index f1d0bbc0f079..d2068bba9059 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -369,6 +369,14 @@ struct kvmppc_slb {
         u8 base_page_size;      /* MMU_PAGE_xxx */
 };
 
+/* Struct used to accumulate timing information in HV real mode code */
+struct kvmhv_tb_accumulator {
+        u64     seqcount;       /* used to synchronize access, also count * 2 */
+        u64     tb_total;       /* total time in timebase ticks */
+        u64     tb_min;         /* min time */
+        u64     tb_max;         /* max time */
+};
+
 # ifdef CONFIG_PPC_FSL_BOOK3E
 #define KVMPPC_BOOKE_IAC_NUM    2
 #define KVMPPC_BOOKE_DAC_NUM    2
@@ -657,6 +665,19 @@ struct kvm_vcpu_arch {
 
         u32 emul_inst;
 #endif
+
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        struct kvmhv_tb_accumulator *cur_activity;      /* What we're timing */
+        u64     cur_tb_start;                   /* when it started */
+        struct kvmhv_tb_accumulator rm_entry;   /* real-mode entry code */
+        struct kvmhv_tb_accumulator rm_intr;    /* real-mode intr handling */
+        struct kvmhv_tb_accumulator rm_exit;    /* real-mode exit code */
+        struct kvmhv_tb_accumulator guest_time; /* guest execution */
+        struct kvmhv_tb_accumulator cede_time;  /* time napping inside guest */
+
+        struct dentry *debugfs_dir;
+        struct dentry *debugfs_timings;
+#endif /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
 };
 
 #define VCPU_FPR(vcpu, i)       (vcpu)->arch.fp.fpr[i][TS_FPROFFSET]
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index 03cbada59d3a..10fc784a2ad4 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -211,5 +211,8 @@ extern void secondary_cpu_time_init(void);
 
 DECLARE_PER_CPU(u64, decrementers_next_tb);
 
+/* Convert timebase ticks to nanoseconds */
+unsigned long long tb_to_ns(unsigned long long tb_ticks);
+
 #endif /* __KERNEL__ */
 #endif /* __POWERPC_TIME_H */
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 4717859fdd04..3fea721f0da5 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -459,6 +459,19 @@ int main(void)
         DEFINE(VCPU_SPRG2, offsetof(struct kvm_vcpu, arch.shregs.sprg2));
         DEFINE(VCPU_SPRG3, offsetof(struct kvm_vcpu, arch.shregs.sprg3));
 #endif
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        DEFINE(VCPU_TB_RMENTRY, offsetof(struct kvm_vcpu, arch.rm_entry));
+        DEFINE(VCPU_TB_RMINTR, offsetof(struct kvm_vcpu, arch.rm_intr));
+        DEFINE(VCPU_TB_RMEXIT, offsetof(struct kvm_vcpu, arch.rm_exit));
+        DEFINE(VCPU_TB_GUEST, offsetof(struct kvm_vcpu, arch.guest_time));
+        DEFINE(VCPU_TB_CEDE, offsetof(struct kvm_vcpu, arch.cede_time));
+        DEFINE(VCPU_CUR_ACTIVITY, offsetof(struct kvm_vcpu, arch.cur_activity));
+        DEFINE(VCPU_ACTIVITY_START, offsetof(struct kvm_vcpu, arch.cur_tb_start));
+        DEFINE(TAS_SEQCOUNT, offsetof(struct kvmhv_tb_accumulator, seqcount));
+        DEFINE(TAS_TOTAL, offsetof(struct kvmhv_tb_accumulator, tb_total));
+        DEFINE(TAS_MIN, offsetof(struct kvmhv_tb_accumulator, tb_min));
+        DEFINE(TAS_MAX, offsetof(struct kvmhv_tb_accumulator, tb_max));
+#endif
         DEFINE(VCPU_SHARED_SPRG3, offsetof(struct kvm_vcpu_arch_shared, sprg3));
         DEFINE(VCPU_SHARED_SPRG4, offsetof(struct kvm_vcpu_arch_shared, sprg4));
         DEFINE(VCPU_SHARED_SPRG5, offsetof(struct kvm_vcpu_arch_shared, sprg5));
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 2d7b33fab953..56f44848b044 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -608,6 +608,12 @@ void arch_suspend_enable_irqs(void)
 }
 #endif
 
+unsigned long long tb_to_ns(unsigned long long ticks)
+{
+        return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
+}
+EXPORT_SYMBOL_GPL(tb_to_ns);
+
 /*
  * Scheduler clock - returns current time in nanosec units.
  *
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index 11850f310fb4..2963e4dd0b80 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -110,6 +110,20 @@ config KVM_BOOK3S_64_PR
           processor, including emulating 32-bit processors on a 64-bit
           host.
 
+config KVM_BOOK3S_HV_EXIT_TIMING
+        bool "Detailed timing for hypervisor real-mode code"
+        depends on KVM_BOOK3S_HV_POSSIBLE && DEBUG_FS
+        ---help---
+          Calculate time taken for each vcpu in the real-mode guest entry,
+          exit, and interrupt handling code, plus time spent in the guest
+          and in nap mode due to idle (cede) while other threads are still
+          in the guest.  The total, minimum and maximum times in nanoseconds
+          together with the number of executions are reported in debugfs in
+          kvm/vm#/vcpu#/timings.  The overhead is of the order of 30 - 40
+          ns per exit on POWER8.
+
+          If unsure, say N.
+
 config KVM_BOOKE_HV
         bool
 
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 08f8617f4046..64a02d4c737c 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -1423,6 +1423,154 @@ static struct kvmppc_vcore *kvmppc_vcore_create(struct kvm *kvm, int core)
         return vcore;
 }
 
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+static struct debugfs_timings_element {
+        const char *name;
+        size_t offset;
+} timings[] = {
+        {"rm_entry",    offsetof(struct kvm_vcpu, arch.rm_entry)},
+        {"rm_intr",     offsetof(struct kvm_vcpu, arch.rm_intr)},
+        {"rm_exit",     offsetof(struct kvm_vcpu, arch.rm_exit)},
+        {"guest",       offsetof(struct kvm_vcpu, arch.guest_time)},
+        {"cede",        offsetof(struct kvm_vcpu, arch.cede_time)},
+};
+
+#define N_TIMINGS       (sizeof(timings) / sizeof(timings[0]))
+
+struct debugfs_timings_state {
+        struct kvm_vcpu *vcpu;
+        unsigned int    buflen;
+        char            buf[N_TIMINGS * 100];
+};
+
+static int debugfs_timings_open(struct inode *inode, struct file *file)
+{
+        struct kvm_vcpu *vcpu = inode->i_private;
+        struct debugfs_timings_state *p;
+
+        p = kzalloc(sizeof(*p), GFP_KERNEL);
+        if (!p)
+                return -ENOMEM;
+
+        kvm_get_kvm(vcpu->kvm);
+        p->vcpu = vcpu;
+        file->private_data = p;
+
+        return nonseekable_open(inode, file);
+}
+
+static int debugfs_timings_release(struct inode *inode, struct file *file)
+{
+        struct debugfs_timings_state *p = file->private_data;
+
+        kvm_put_kvm(p->vcpu->kvm);
+        kfree(p);
+        return 0;
+}
+
+static ssize_t debugfs_timings_read(struct file *file, char __user *buf,
+                                    size_t len, loff_t *ppos)
+{
+        struct debugfs_timings_state *p = file->private_data;
+        struct kvm_vcpu *vcpu = p->vcpu;
+        char *s, *buf_end;
+        struct kvmhv_tb_accumulator tb;
+        u64 count;
+        loff_t pos;
+        ssize_t n;
+        int i, loops;
+        bool ok;
+
+        if (!p->buflen) {
+                s = p->buf;
+                buf_end = s + sizeof(p->buf);
+                for (i = 0; i < N_TIMINGS; ++i) {
+                        struct kvmhv_tb_accumulator *acc;
+
+                        acc = (struct kvmhv_tb_accumulator *)
+                                ((unsigned long)vcpu + timings[i].offset);
+                        ok = false;
+                        for (loops = 0; loops < 1000; ++loops) {
+                                count = acc->seqcount;
+                                if (!(count & 1)) {
+                                        smp_rmb();
+                                        tb = *acc;
+                                        smp_rmb();
+                                        if (count == acc->seqcount) {
+                                                ok = true;
+                                                break;
+                                        }
+                                }
+                                udelay(1);
+                        }
+                        if (!ok)
+                                snprintf(s, buf_end - s, "%s: stuck\n",
+                                        timings[i].name);
+                        else
+                                snprintf(s, buf_end - s,
+                                        "%s: %llu %llu %llu %llu\n",
+                                        timings[i].name, count / 2,
+                                        tb_to_ns(tb.tb_total),
+                                        tb_to_ns(tb.tb_min),
+                                        tb_to_ns(tb.tb_max));
+                        s += strlen(s);
+                }
+                p->buflen = s - p->buf;
+        }
+
+        pos = *ppos;
+        if (pos >= p->buflen)
+                return 0;
+        if (len > p->buflen - pos)
+                len = p->buflen - pos;
+        n = copy_to_user(buf, p->buf + pos, len);
+        if (n) {
+                if (n == len)
+                        return -EFAULT;
+                len -= n;
+        }
+        *ppos = pos + len;
+        return len;
+}
+
+static ssize_t debugfs_timings_write(struct file *file, const char __user *buf,
+                                     size_t len, loff_t *ppos)
+{
+        return -EACCES;
+}
+
+static const struct file_operations debugfs_timings_ops = {
+        .owner   = THIS_MODULE,
+        .open    = debugfs_timings_open,
+        .release = debugfs_timings_release,
+        .read    = debugfs_timings_read,
+        .write   = debugfs_timings_write,
+        .llseek  = generic_file_llseek,
+};
+
+/* Create a debugfs directory for the vcpu */
+static void debugfs_vcpu_init(struct kvm_vcpu *vcpu, unsigned int id)
+{
+        char buf[16];
+        struct kvm *kvm = vcpu->kvm;
+
+        snprintf(buf, sizeof(buf), "vcpu%u", id);
+        if (IS_ERR_OR_NULL(kvm->arch.debugfs_dir))
+                return;
+        vcpu->arch.debugfs_dir = debugfs_create_dir(buf, kvm->arch.debugfs_dir);
+        if (IS_ERR_OR_NULL(vcpu->arch.debugfs_dir))
+                return;
+        vcpu->arch.debugfs_timings =
+                debugfs_create_file("timings", 0444, vcpu->arch.debugfs_dir,
+                                    vcpu, &debugfs_timings_ops);
+}
+
+#else /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
+static void debugfs_vcpu_init(struct kvm_vcpu *vcpu, unsigned int id)
+{
+}
+#endif /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
+
 static struct kvm_vcpu *kvmppc_core_vcpu_create_hv(struct kvm *kvm,
                                                    unsigned int id)
 {
@@ -1492,6 +1640,8 @@ static struct kvm_vcpu *kvmppc_core_vcpu_create_hv(struct kvm *kvm,
         vcpu->arch.cpu_type = KVM_CPU_3S_64;
         kvmppc_sanity_check(vcpu);
 
+        debugfs_vcpu_init(vcpu, id);
+
         return vcpu;
 
 free_vcpu:
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 0814ca122fcd..b06fe53fd509 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -225,7 +225,13 @@ kvm_novcpu_wakeup:
         /* Got an IPI but other vcpus aren't yet exiting, must be a latecomer */
         ld      r4, HSTATE_KVM_VCPU(r13)
         cmpdi   r4, 0
-        bne     kvmppc_got_guest
+        beq     kvmppc_primary_no_guest
+
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        addi    r3, r4, VCPU_TB_RMENTRY
+        bl      kvmhv_start_timing
+#endif
+        b       kvmppc_got_guest
 
 kvm_novcpu_exit:
         b       hdec_soon
@@ -376,6 +382,14 @@ kvmppc_hv_entry:
         li      r6, KVM_GUEST_MODE_HOST_HV
         stb     r6, HSTATE_IN_GUEST(r13)
 
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        /* Store initial timestamp */
+        cmpdi   r4, 0
+        beq     1f
+        addi    r3, r4, VCPU_TB_RMENTRY
+        bl      kvmhv_start_timing
+1:
+#endif
         /* Clear out SLB */
         li      r6,0
         slbmte  r6,r6
@@ -880,6 +894,12 @@ fast_guest_return:
         li      r9, KVM_GUEST_MODE_GUEST_HV
         stb     r9, HSTATE_IN_GUEST(r13)
 
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        /* Accumulate timing */
+        addi    r3, r4, VCPU_TB_GUEST
+        bl      kvmhv_accumulate_time
+#endif
+
         /* Enter guest */
 
 BEGIN_FTR_SECTION
@@ -917,6 +937,23 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
         hrfid
         b       .
 
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+secondary_too_late:
+        cmpdi   r4, 0
+        beq     11f
+        addi    r3, r4, VCPU_TB_RMEXIT
+        bl      kvmhv_accumulate_time
+11:     b       kvmhv_switch_to_host
+
+hdec_soon:
+        ld      r4, HSTATE_KVM_VCPU(r13)
+        cmpdi   r4, 0
+        beq     12f
+        addi    r3, r4, VCPU_TB_RMEXIT
+        bl      kvmhv_accumulate_time
+12:     b       kvmhv_do_exit
+#endif
+
 /******************************************************************************
  *                                                                            *
  *                               Exit code                                    *
@@ -1002,6 +1039,16 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 
         stw     r12,VCPU_TRAP(r9)
 
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        addi    r3, r9, VCPU_TB_RMINTR
+        mr      r4, r9
+        bl      kvmhv_accumulate_time
+        ld      r5, VCPU_GPR(R5)(r9)
+        ld      r6, VCPU_GPR(R6)(r9)
+        ld      r7, VCPU_GPR(R7)(r9)
+        ld      r8, VCPU_GPR(R8)(r9)
+#endif
+
         /* Save HEIR (HV emulation assist reg) in emul_inst
            if this is an HEI (HV emulation interrupt, e40) */
         li      r3,KVM_INST_FETCH_FAILED
@@ -1073,6 +1120,11 @@ guest_exit_cont:		/* r9 = vcpu, r12 = trap, r13 = paca */
         cmpwi   r12, BOOK3S_INTERRUPT_MACHINE_CHECK
         beq     machine_check_realmode
 mc_cont:
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        addi    r3, r9, VCPU_TB_RMEXIT
+        mr      r4, r9
+        bl      kvmhv_accumulate_time
+#endif
 
         /* Save guest CTRL register, set runlatch to 1 */
 6:      mfspr   r6,SPRN_CTRLF
@@ -1417,7 +1469,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
         slbia
         ptesync
 
-hdec_soon:                      /* r12 = trap, r13 = paca */
+#ifndef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+hdec_soon:
+#endif
+kvmhv_do_exit:                  /* r12 = trap, r13 = paca */
         /*
          * POWER7/POWER8 guest -> host partition switch code.
          * We don't have to lock against tlbies but we do
@@ -1476,7 +1531,10 @@ hdec_soon:			/* r12 = trap, r13 = paca */
         addi    r6,r6,PACA_SIZE
         bne     42b
 
+#ifndef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
 secondary_too_late:
+#endif
+kvmhv_switch_to_host:
         /* Secondary threads wait for primary to do partition switch */
 43:     ld      r5,HSTATE_KVM_VCORE(r13)
         ld      r4,VCORE_KVM(r5)        /* pointer to struct kvm */
@@ -1562,6 +1620,15 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 1:      addi    r8,r8,16
         .endr
 
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        /* Finish timing, if we have a vcpu */
+        ld      r4, HSTATE_KVM_VCPU(r13)
+        cmpdi   r4, 0
+        li      r3, 0
+        beq     2f
+        bl      kvmhv_accumulate_time
+2:
+#endif
         /* Unset guest mode */
         li      r0, KVM_GUEST_MODE_NONE
         stb     r0, HSTATE_IN_GUEST(r13)
@@ -2069,6 +2136,12 @@ _GLOBAL(kvmppc_h_cede)
         /* save FP state */
         bl      kvmppc_save_fp
 
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        ld      r4, HSTATE_KVM_VCPU(r13)
+        addi    r3, r4, VCPU_TB_CEDE
+        bl      kvmhv_accumulate_time
+#endif
+
         /*
          * Take a nap until a decrementer or external or doobell interrupt
          * occurs, with PECE1, PECE0 and PECEDP set in LPCR. Also clear the
@@ -2109,6 +2182,11 @@ kvm_end_cede:
         /* Woken by external or decrementer interrupt */
         ld      r1, HSTATE_HOST_R1(r13)
 
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+        addi    r3, r4, VCPU_TB_RMINTR
+        bl      kvmhv_accumulate_time
+#endif
+
         /* load up FP state */
         bl      kvmppc_load_fp
 
@@ -2429,3 +2507,62 @@ kvmppc_fix_pmao:
         mtspr   SPRN_PMC6, r3
         isync
         blr
+
+#ifdef CONFIG_KVM_BOOK3S_HV_EXIT_TIMING
+/*
+ * Start timing an activity
+ * r3 = pointer to time accumulation struct, r4 = vcpu
+ */
+kvmhv_start_timing:
+        ld      r5, HSTATE_KVM_VCORE(r13)
+        lbz     r6, VCORE_IN_GUEST(r5)
+        cmpwi   r6, 0
+        beq     5f                              /* if in guest, need to */
+        ld      r6, VCORE_TB_OFFSET(r5)         /* subtract timebase offset */
+5:      mftb    r5
+        subf    r5, r6, r5
+        std     r3, VCPU_CUR_ACTIVITY(r4)
+        std     r5, VCPU_ACTIVITY_START(r4)
+        blr
+
+/*
+ * Accumulate time to one activity and start another.
+ * r3 = pointer to new time accumulation struct, r4 = vcpu
+ */
+kvmhv_accumulate_time:
+        ld      r5, HSTATE_KVM_VCORE(r13)
+        lbz     r8, VCORE_IN_GUEST(r5)
+        cmpwi   r8, 0
+        beq     4f                              /* if in guest, need to */
+        ld      r8, VCORE_TB_OFFSET(r5)         /* subtract timebase offset */
+4:      ld      r5, VCPU_CUR_ACTIVITY(r4)
+        ld      r6, VCPU_ACTIVITY_START(r4)
+        std     r3, VCPU_CUR_ACTIVITY(r4)
+        mftb    r7
+        subf    r7, r8, r7
+        std     r7, VCPU_ACTIVITY_START(r4)
+        cmpdi   r5, 0
+        beqlr
+        subf    r3, r6, r7
+        ld      r8, TAS_SEQCOUNT(r5)
+        cmpdi   r8, 0
+        addi    r8, r8, 1
+        std     r8, TAS_SEQCOUNT(r5)
+        lwsync
+        ld      r7, TAS_TOTAL(r5)
+        add     r7, r7, r3
+        std     r7, TAS_TOTAL(r5)
+        ld      r6, TAS_MIN(r5)
+        ld      r7, TAS_MAX(r5)
+        beq     3f
+        cmpd    r3, r6
+        bge     1f
+3:      std     r3, TAS_MIN(r5)
+1:      cmpd    r3, r7
+        ble     2f
+        std     r3, TAS_MAX(r5)
+2:      lwsync
+        addi    r8, r8, 1
+        std     r8, TAS_SEQCOUNT(r5)
+        blr
+#endif