Messages in this thread | | | Subject | Re: [PATCH v3 00/17] KVM: x86/pmu: Add support to enable Guest PEBS via DS | From | "Liuxiangdong (Aven, Cloud Infrastructure Service Product Dept.)" <> | Date | Mon, 25 Jan 2021 22:47:19 +0800 |
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Thanks for replying,
On 2021/1/25 10:41, Like Xu wrote: > + kvm@vger.kernel.org > > Hi Liuxiangdong, > > On 2021/1/22 18:02, Liuxiangdong (Aven, Cloud Infrastructure Service > Product Dept.) wrote: >> Hi Like, >> >> Some questions about >> https://lore.kernel.org/kvm/20210104131542.495413-1-like.xu@linux.intel.com/ >> <https://lore.kernel.org/kvm/20210104131542.495413-1-like.xu@linux.intel.com/> >> > > Thanks for trying the PEBS feature in the guest, > and I assume you have correctly applied the QEMU patches for guest PEBS. > Is there any other patch that needs to be apply? I use qemu 5.2.0. (download from github on January 14th)
>> 1)Test in IceLake > > In the [PATCH v3 10/17] KVM: x86/pmu: Expose CPUIDs feature bits PDCM, > DS, DTES64, we only support Ice Lake with the following x86_model(s): > > #define INTEL_FAM6_ICELAKE_X 0x6A > #define INTEL_FAM6_ICELAKE_D 0x6C > > you can check the eax output of "cpuid -l 1 -1 -r", > for example "0x000606a4" meets this requirement. It's INTEL_FAM6_ICELAKE_X cpuid -l 1 -1 -r
CPU: 0x00000001 0x00: eax=0x000606a6 ebx=0xb4800800 ecx=0x7ffefbf7 edx=0xbfebfbff
>> >> HOST: >> >> CPU family: 6 >> >> Model: 106 >> >> Model name: Intel(R) Xeon(R) Platinum 8378A CPU >> $@ $@ >> >> microcode: sig=0x606a6, pf=0x1, revision=0xd000122 > > As long as you get the latest BIOS from the provider, > you may check 'cat /proc/cpuinfo | grep code | uniq' with the latest one. OK. I'll do it later. > >> >> Guest: linux kernel 5.11.0-rc2 > > I assume it's the "upstream tag v5.11-rc2" which is fine. Yes. > >> >> We can find pebs/intel_pt flag in guest cpuinfo, but there still >> exists error when we use perf > > Just a note, intel_pt and pebs are two features and we can write > pebs records to intel_pt buffer with extra hardware support. > (by default, pebs records are written to the pebs buffer) > > You may check the output of "dmesg | grep PEBS" in the guest > to see if the guest PEBS cpuinfo is exposed and use "perf record > –e cycles:pp" to see if PEBS feature actually works in the guest.
I apply only pebs patch set to linux kernel 5.11.0-rc2, test perf in guest and dump stack when return -EOPNOTSUPP
(1) # perf record -e instructions:pp Error: instructions:pp: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'
[ 117.793266] Call Trace: [ 117.793270] dump_stack+0x57/0x6a [ 117.793275] intel_pmu_setup_lbr_filter+0x137/0x190 [ 117.793280] intel_pmu_hw_config+0x18b/0x320 [ 117.793288] hsw_hw_config+0xe/0xa0 [ 117.793290] x86_pmu_event_init+0x8e/0x210 [ 117.793293] perf_try_init_event+0x40/0x130 [ 117.793297] perf_event_alloc.part.22+0x611/0xde0 [ 117.793299] ? alloc_fd+0xba/0x180 [ 117.793302] __do_sys_perf_event_open+0x1bd/0xd90 [ 117.793305] do_syscall_64+0x33/0x40 [ 117.793308] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Do we need lbr when we use pebs?
I tried to apply lbr patch set(https://lore.kernel.org/kvm/911adb63-ba05-ea93-c038-1c09cff15eda@intel.com/) to kernel and qemu, but there is still other problem. Error: The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event ...
(2) # perf record -e instructions:ppp Error: instructions:ppp: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat'
[ 115.188498] Call Trace: [ 115.188503] dump_stack+0x57/0x6a [ 115.188509] x86_pmu_hw_config+0x1eb/0x220 [ 115.188515] intel_pmu_hw_config+0x13/0x320 [ 115.188519] hsw_hw_config+0xe/0xa0 [ 115.188521] x86_pmu_event_init+0x8e/0x210 [ 115.188524] perf_try_init_event+0x40/0x130 [ 115.188528] perf_event_alloc.part.22+0x611/0xde0 [ 115.188530] ? alloc_fd+0xba/0x180 [ 115.188534] __do_sys_perf_event_open+0x1bd/0xd90 [ 115.188538] do_syscall_64+0x33/0x40 [ 115.188541] entry_SYSCALL_64_after_hwframe+0x44/0xa9
This is beacuse x86_pmu.intel_cap.pebs_format is always 0 in x86_pmu_max_precise().
We rdmsr MSR_IA32_PERF_CAPABILITIES(0x00000345) from HOST, it's f4c5. From guest, it's 2000
>> >> # perf record –e cycles:pp >> >> Error: >> >> cycles:pp: PMU Hardware doesn’t support sampling/overflow-interrupts. >> Try ‘perf stat’ >> >> Could you give some advice? > > If you have more specific comments or any concerns, just let me know. > >> >> 2)Test in Skylake >> >> HOST: >> >> CPU family: 6 >> >> Model: 85 >> >> Model name: Intel(R) Xeon(R) Gold 6146 CPU @ >> >> 3.20GHz >> >> microcode : 0x2000064 >> >> Guest: linux 4.18 >> >> we cannot find intel_pt flag in guest cpuinfo because >> cpu_has_vmx_intel_pt() return false. > > You may check vmx_pebs_supported(). It's true. > >> >> SECONDARY_EXEC_PT_USE_GPA/VM_EXIT_CLEAR_IA32_RTIT_CTL/VM_ENTRY_LOAD_IA32_RTIT_CTL >> are both disable. >> >> Is it because microcode is not supported? >> >> And, isthere a new macrocode which can support these bits? How can we >> get this? > > Currently, this patch set doesn't support guest PEBS on the Skylake > platforms, and if we choose to support it, we will let you know. > And now, we want to use pebs in skylake. If we develop based on pebs patch set, do you have any suggestions? I think microcode requirements need to be satisfied. Can we use https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files ?
> --- > thx,likexu > >> >> Thanks, >> >> Liuxiangdong >> > Thanks. Liuxiangdong
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