https://bugzilla.kernel.org/show_bug.cgi?id=99861 Bug ID: 99861 Summary: KVM: Linux host warns "user requested TSC rate below hardware speed" on the Baytrail-I platform when start a guest Product: Virtualization Version: unspecified Kernel Version: 4.1.0-rc3+ Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: kvm Assignee: virtualization_kvm@xxxxxxxxxxxxxxxxxxxx Reporter: chao.zhou@xxxxxxxxx CC: tianyu.lan@xxxxxxxxx Regression: No Environment: ------------ Host OS (ia32/ia32e/IA64): ia32/ia64 Guest OS (ia32/ia32e/IA64): ia32/ia32e/IA64 Guest OS Type (Linux/Windows): Linux/Windows kvm.git Commit: c0655fe9b0901a968800f56687be3c62b4cce5d2 qemu-kvm Commit: f053f6b83d01b47adf3b8f29eb0c0769755d1f9c Host Kernel Version: 4.1.0-rc3+ Hardware: Baytrail-I platform Bug detailed description: -------------------------- Linux host warns "user requested TSC rate below hardware speed" on the Baytrail-I platform when start a guest. The warning is caused by guest tsc setting mismatch with host tsc. KVM records tsc value during Arch init stage while the tsc value may be changed during tsc clock source driver is loaded and refine tsc freq calibration. KVM starts a guest with old tsc value and trigger the warning. Attach a draft patch to fix the issue. Reproduce steps: ---------------- Run a guest Current result: ---------------- Linux host produce warning Expected result: ---------------- No warning. Basic root-causing log: ---------------------- [ 1042.255614] ------------[ cut here ]------------ [ 1042.260804] WARNING: CPU: 2 PID: 5232 at arch/x86/kvm/vmx.c:2272 vmx_set_tsc_khz+0x3e/0x50() [ 1042.270266] user requested TSC rate below hardware speed [ 1042.276222] Modules linked in: [ 1042.279657] CPU: 2 PID: 5232 Comm: qemu-system-x86 Tainted: G D W 4.1.0-rc3+ #2 [ 1042.288923] Hardware name: Huawei Technologies Co., Ltd. AR16XA OSP/Aptio CRB, BIOS 5.6.5 04/17/2015 [ 1042.299160] ffffffff81f453f8 ffff88026655fbc8 ffffffff81b5eb8a 0000000000000000 [ 1042.307498] ffff88026655fc18 ffff88026655fc08 ffffffff810e6f8a ffff880200000000 [ 1042.315834] 00000000001d3300 ffff880274100000 0000000000000001 ffff880274100000 [ 1042.324169] Call Trace: [ 1042.326926] [<ffffffff81b5eb8a>] dump_stack+0x45/0x57 [ 1042.332693] [<ffffffff810e6f8a>] warn_slowpath_common+0x8a/0xc0 [ 1042.339432] [<ffffffff810e7006>] warn_slowpath_fmt+0x46/0x50 [ 1042.345884] [<ffffffff81253c9e>] ? alloc_pages_current+0x10e/0x1d0 [ 1042.352913] [<ffffffff8101e48b>] ? kvm_arch_vcpu_init+0x6b/0x230 [ 1042.359754] [<ffffffff8104676e>] vmx_set_tsc_khz+0x3e/0x50 [ 1042.366005] [<ffffffff810112f7>] kvm_set_tsc_khz.part.106+0xa7/0xe0 [ 1042.373136] [<ffffffff8101e628>] kvm_arch_vcpu_init+0x208/0x230 [ 1042.379877] [<ffffffff81003bf9>] kvm_vcpu_init+0xc9/0x110 [ 1042.386037] [<ffffffff81049fd0>] vmx_create_vcpu+0x70/0xc30 [ 1042.392390] [<ffffffff8112a5c8>] ? pick_next_task_fair+0x1d8/0xc50 [ 1042.399420] [<ffffffff8101dc9e>] kvm_arch_vcpu_create+0x3e/0x60 [ 1042.406157] [<ffffffff81009f00>] kvm_vm_ioctl+0x1a0/0x770 [ 1042.412313] [<ffffffff8129f395>] ? __fget+0x5/0x200 [ 1042.417886] [<ffffffff81293448>] do_vfs_ioctl+0x308/0x540 [ 1042.424044] [<ffffffff8129f301>] ? expand_files+0x1f1/0x280 [ 1042.430395] [<ffffffff8147836b>] ? selinux_file_ioctl+0x5b/0x100 [ 1042.437231] [<ffffffff81293701>] SyS_ioctl+0x81/0xa0 [ 1042.442900] [<ffffffff81b6a72e>] system_call_fastpath+0x12/0x76 [ 1042.449639] ---[ end trace 93158310429e56fc ]--- -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
