Hi Luwei,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kvm/linux-next]
[also build test ERROR on tip/perf/core tip/auto-latest v5.6-rc4 next-20200306]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Luwei-Kang/PEBS-virtualization-enabling-via-DS/20200306-013049
base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
config: x86_64-randconfig-h003-20200305 (attached as .config)
compiler: gcc-7 (Debian 7.5.0-5) 7.5.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   ld: arch/x86/kvm/pmu.o: in function `pmc_reprogram_counter':
>> arch/x86/kvm/pmu.c:199: undefined reference to `perf_x86_pmu_unset_auto_reload'

vim +199 arch/x86/kvm/pmu.c

   101	
   102	static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
   103					  unsigned config, bool exclude_user,
   104					  bool exclude_kernel, bool intr,
   105					  bool in_tx, bool in_tx_cp)
   106	{
   107		struct kvm_pmu *pmu = vcpu_to_pmu(pmc->vcpu);
   108		struct perf_event *event;
   109		struct perf_event_attr attr = {
   110			.type = type,
   111			.size = sizeof(attr),
   112			.pinned = true,
   113			.exclude_idle = true,
   114			.exclude_host = 1,
   115			.exclude_user = exclude_user,
   116			.exclude_kernel = exclude_kernel,
   117			.config = config,
   118			.disabled = 1,
   119		};
   120		bool pebs = test_bit(pmc->idx, (unsigned long *)&pmu->pebs_enable);
   121	
   122		attr.sample_period = (-pmc->counter) & pmc_bitmask(pmc);
   123	
   124		if (in_tx)
   125			attr.config |= HSW_IN_TX;
   126		if (in_tx_cp) {
   127			/*
   128			 * HSW_IN_TX_CHECKPOINTED is not supported with nonzero
   129			 * period. Just clear the sample period so at least
   130			 * allocating the counter doesn't fail.
   131			 */
   132			attr.sample_period = 0;
   133			attr.config |= HSW_IN_TX_CHECKPOINTED;
   134		}
   135	
   136		if (pebs) {
   137			/*
   138			 * Host never knows the precision level set by guest.
   139			 * Force Host's PEBS event to precision level 1, which will
   140			 * not impact the accuracy of the results for guest PEBS events.
   141			 * Because,
   142			 * - For most cases, there is no difference among precision
   143			 *   level 1 to 3 for PEBS events.
   144			 * - The functions as below checks the precision level in host.
   145			 *   But the results from these functions in host are replaced
   146			 *   by guest when sampling the guest.
   147			 *   The accuracy for guest PEBS events will not be impacted.
   148			 *    -- event_constraints() impacts the index of counter.
   149			 *	The index for host event is exactly the same as guest.
   150			 *	It's decided by guest.
   151			 *    -- pebs_update_adaptive_cfg() impacts the value of
   152			 *	MSR_PEBS_DATA_CFG. When guest is switched in,
   153			 *	the MSR value will be replaced by the value from guest.
   154			 *    -- setup_sample () impacts the output of a PEBS record.
   155			 *	Guest handles the PEBS records.
   156			 */
   157			attr.precise_ip = 1;
   158			/*
   159			 * When the host's PMI handler completes, it's going to
   160			 * enter the guest and trigger the guest's PMI handler.
   161			 *
   162			 * At this moment, this function may be called by
   163			 * kvm_pmu_handle_event(). However the next sample_period
   164			 * hasn't been determined by guest yet and the left period,
   165			 * which probably be 0, is used for current sample_period.
   166			 *
   167			 * In this case, perf will mistakenly treat it as non
   168			 * sampling events. The PEBS event will error out.
   169			 *
   170			 * Fill it with maximum period to prevent the error out.
   171			 * The guest PMI handler will soon reprogram the counter.
   172			 */
   173			if (!attr.sample_period)
   174				attr.sample_period = (-1ULL) & pmc_bitmask(pmc);
   175		}
   176	
   177		event = perf_event_create_kernel_counter(&attr, -1, current,
   178							 (intr || pebs) ?
   179							 kvm_perf_overflow_intr :
   180							 kvm_perf_overflow, pmc);
   181		if (IS_ERR(event)) {
   182			pr_debug_ratelimited("kvm_pmu: event creation failed %ld for pmc->idx = %d\n",
   183				    PTR_ERR(event), pmc->idx);
   184			return;
   185		}
   186	
   187		if (pebs) {
   188			event->guest_dedicated_idx = pmc->idx;
   189			/*
   190			 * For guest PEBS events, guest takes the responsibility to
   191			 * drain PEBS buffers, and load proper values to reset counters.
   192			 *
   193			 * Host will unconditionally set auto-reload flag for PEBS
   194			 * events with fixed period which is not necessary. Host should
   195			 * do nothing in drain_pebs() but inject the PMI into the guest.
   196			 *
   197			 * Unset the auto-reload flag for guest PEBS events.
   198			 */
 > 199			perf_x86_pmu_unset_auto_reload(event);
   200		}
   201		pmc->perf_event = event;
   202		pmc_to_pmu(pmc)->event_count++;
   203		perf_event_enable(event);
   204		clear_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi);
   205	}
   206	

---
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