У вт, 2023-10-10 у 09:31 -0700, Dongli Zhang пише: > Hi Maxim, > > On 10/10/23 09:13, Maxim Levitsky wrote: > > У пт, 2023-10-06 у 10:57 -0700, Dongli Zhang пише: > > > As inspired by the discussion in [1], the boottime wallclock may drift due > > > to the fact that the masterclock (or host monotonic clock) and kvmclock are > > > calculated based on the algorithms in different domains. > > > > > > This is to introduce a testcase to print the boottime wallclock > > > periodically to help diagnose the wallclock drift issue in the future. > > > > > > The idea is to wrmsr the MSR_KVM_WALL_CLOCK_NEW, and read the boottime > > > wallclock nanoseconds immediately. > > > > > > References: > > > [1] https://urldefense.com/v3/__https://lore.kernel.org/all/20231001111313.77586-1-nsaenz@amazon.com__;!!ACWV5N9M2RV99hQ!MOnoujF4PlfvZ3SUuyXgIpJC5mWiE5uLUsNW6AWgirGXcObN5uil_fnthRVcYaPA0N2uoNyLChBogHC7ZS6t$ > > > > > > Cc: David Woodhouse <dwmw@xxxxxxxxxxxx> > > > Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx> > > > --- > > > tools/testing/selftests/kvm/Makefile | 3 +- > > > .../selftests/kvm/x86_64/boottime_wallclock.c | 100 ++++++++++++++++++ > > > 2 files changed, 102 insertions(+), 1 deletion(-) > > > create mode 100644 tools/testing/selftests/kvm/x86_64/boottime_wallclock.c > > > > > > diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile > > > index a3bb36fb3cfc..fea05b0118de 100644 > > > --- a/tools/testing/selftests/kvm/Makefile > > > +++ b/tools/testing/selftests/kvm/Makefile > > > @@ -60,7 +60,8 @@ LIBKVM_riscv += lib/riscv/ucall.c > > > TEST_PROGS_x86_64 += x86_64/nx_huge_pages_test.sh > > > > > > # Compiled test targets > > > -TEST_GEN_PROGS_x86_64 = x86_64/cpuid_test > > > +TEST_GEN_PROGS_x86_64 = x86_64/boottime_wallclock > > > +TEST_GEN_PROGS_x86_64 += x86_64/cpuid_test > > > TEST_GEN_PROGS_x86_64 += x86_64/cr4_cpuid_sync_test > > > TEST_GEN_PROGS_x86_64 += x86_64/dirty_log_page_splitting_test > > > TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features > > > diff --git a/tools/testing/selftests/kvm/x86_64/boottime_wallclock.c b/tools/testing/selftests/kvm/x86_64/boottime_wallclock.c > > > new file mode 100644 > > > index 000000000000..cc48c9b19920 > > > --- /dev/null > > > +++ b/tools/testing/selftests/kvm/x86_64/boottime_wallclock.c > > > @@ -0,0 +1,100 @@ > > > +// SPDX-License-Identifier: GPL-2.0-only > > > +/* > > > + * Copyright (C) 2023 Oracle and/or its affiliates. > > > + */ > > > + > > > +#include <asm/kvm_para.h> > > > +#include <asm/pvclock-abi.h> > > > + > > > +#include "kvm_util.h" > > > +#include "processor.h" > > > + > > > +static int period = 10; > > > + > > > +#define GUEST_SYNC_WALLCLOCK(__stage, __val) \ > > > + GUEST_SYNC_ARGS(__stage, __val, 0, 0, 0) > > > + > > > +static void guest_main(vm_paddr_t wc_pa, struct pvclock_wall_clock *wc) > > > +{ > > > + uint64_t wallclock; > > > + > > > + while (true) { > > > + wrmsr(MSR_KVM_WALL_CLOCK_NEW, wc_pa); > > > + > > > + wallclock = wc->sec * NSEC_PER_SEC + wc->nsec; > > > + > > > + GUEST_SYNC_WALLCLOCK(0, wallclock); > > > > Won't this fill the output very fast? > > Do you think it will be worth it to wait some time (e.g 1 second or at least 1/10 of a second) > > between each print? > > The wait time is controlled by the VMM side (of selftest) as in below. > > In the while loop at VMM side, it sleeps for a period (configurable argument), > until it runs into the guest again. > > Therefore, the user can decide the frequency to print the boottime wallclock. Sorry about this, I haven't noticed this code! Best regards, Maxim Levitsky > > +static void enter_guest(struct kvm_vcpu *vcpu) > +{ > + struct ucall uc; > + > + while (true) { > + vcpu_run(vcpu); -----------> to schedule guest vcpu here > + > + TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); > + > + switch (get_ucall(vcpu, &uc)) { > + case UCALL_SYNC: > + handle_sync(&uc); > + break; > + case UCALL_ABORT: > + handle_abort(&uc); > + return; > + default: > + TEST_ASSERT(0, "unhandled ucall: %ld\n", uc.cmd); > + return; > + } > + > + sleep(period); ------------> sleep here > + } > +} > > Thank you very much! > > Dongli Zhang > > > > + } > > > +} > > > + > > > +static void handle_sync(struct ucall *uc) > > > +{ > > > + uint64_t wallclock; > > > + > > > + wallclock = uc->args[2]; > > > + > > > + pr_info("Boottime wallclock value: %"PRIu64" ns\n", wallclock); > > > +} > > > + > > > +static void handle_abort(struct ucall *uc) > > > +{ > > > + REPORT_GUEST_ASSERT(*uc); > > > +} > > > + > > > +static void enter_guest(struct kvm_vcpu *vcpu) > > > +{ > > > + struct ucall uc; > > > + > > > + while (true) { > > > + vcpu_run(vcpu); > > > + > > > + TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); > > > + > > > + switch (get_ucall(vcpu, &uc)) { > > > + case UCALL_SYNC: > > > + handle_sync(&uc); > > > + break; > > > + case UCALL_ABORT: > > > + handle_abort(&uc); > > > + return; > > > + default: > > > + TEST_ASSERT(0, "unhandled ucall: %ld\n", uc.cmd); > > > + return; > > > + } > > > + > > > + sleep(period); > > > + } > > > +} > > > + > > > +int main(int argc, char *argv[]) > > > +{ > > > + struct kvm_vcpu *vcpu; > > > + struct kvm_vm *vm; > > > + vm_vaddr_t wc_gva; > > > + vm_paddr_t wc_gpa; > > > + int opt; > > > + > > > + while ((opt = getopt(argc, argv, "p:h")) != -1) { > > > + switch (opt) { > > > + case 'p': > > > + period = atoi_positive("The period (seconds)", optarg); > > > + break; > > > + case 'h': > > > + default: > > > + pr_info("usage: %s [-p period (seconds)]\n", argv[0]); > > > + exit(1); > > > + } > > > + } > > > + > > > + pr_info("Capture boottime wallclock every %d seconds.\n", period); > > > + pr_info("Stop with Ctrl + c.\n\n"); > > > + > > > + vm = vm_create_with_one_vcpu(&vcpu, guest_main); > > > + > > > + wc_gva = vm_vaddr_alloc(vm, getpagesize(), 0x10000); > > > + wc_gpa = addr_gva2gpa(vm, wc_gva); > > > + vcpu_args_set(vcpu, 2, wc_gpa, wc_gva); > > > + > > > + enter_guest(vcpu); > > > + kvm_vm_free(vm); > > > +} > > > > Best regards, > > Maxim Levitsky > > > >
