linux/arch/x86
Marcelo Tosatti 53fafdbb8b KVM: x86: switch KVMCLOCK base to monotonic raw clock
Commit 0bc48bea36 ("KVM: x86: update master clock before computing
kvmclock_offset")
switches the order of operations to avoid the conversion

TSC (without frequency correction) ->
system_timestamp (with frequency correction),

which might cause a time jump.

However, it leaves any other masterclock update unsafe, which includes,
at the moment:

        * HV_X64_MSR_REFERENCE_TSC MSR write.
        * TSC writes.
        * Host suspend/resume.

Avoid the time jump issue by using frequency uncorrected
CLOCK_MONOTONIC_RAW clock.

Its the guests time keeping software responsability
to track and correct a reference clock such as UTC.

This fixes forward time jump (which can result in
failure to bring up a vCPU) during vCPU hotplug:

Oct 11 14:48:33 storage kernel: CPU2 has been hot-added
Oct 11 14:48:34 storage kernel: CPU3 has been hot-added
Oct 11 14:49:22 storage kernel: smpboot: Booting Node 0 Processor 2 APIC 0x2          <-- time jump of almost 1 minute
Oct 11 14:49:22 storage kernel: smpboot: do_boot_cpu failed(-1) to wakeup CPU#2
Oct 11 14:49:23 storage kernel: smpboot: Booting Node 0 Processor 3 APIC 0x3
Oct 11 14:49:23 storage kernel: kvm-clock: cpu 3, msr 0:7ff640c1, secondary cpu clock

Which happens because:

                /*
                 * Wait 10s total for a response from AP
                 */
                boot_error = -1;
                timeout = jiffies + 10*HZ;
                while (time_before(jiffies, timeout)) {
                         ...
                }

Analyzed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-11-02 11:42:02 +01:00
..
boot x86/boot/acpi: Move get_cmdline_acpi_rsdp() under #ifdef guard 2019-10-18 13:33:38 +02:00
configs x86/defconfigs: Remove useless UEVENT_HELPER_PATH 2019-06-21 19:22:08 +02:00
crypto crypto: x86/aes-ni - use AES library instead of single-use AES cipher 2019-09-09 23:48:41 +10:00
entry Kbuild updates for v5.4 2019-09-20 08:36:47 -07:00
events perf/x86/cstate: Add Tiger Lake CPU support 2019-10-12 15:13:09 +02:00
hyperv x86/hyperv: Make vapic support x2apic mode 2019-10-15 10:57:09 +02:00
ia32 clone: fix CLONE_PIDFD support 2019-07-14 20:36:12 +02:00
include KVM: x86: Introduce vcpu->arch.xsaves_enabled 2019-10-22 15:42:48 +02:00
kernel x86/kvm: Fix -Wmissing-prototypes warnings 2019-10-25 14:01:14 +02:00
kvm KVM: x86: switch KVMCLOCK base to monotonic raw clock 2019-11-02 11:42:02 +01:00
lib x86/asm: Fix MWAITX C-state hint value 2019-10-08 13:25:24 +02:00
math-emu x86/fpu/math-emu: Address fallthrough warnings 2019-08-12 20:35:05 +02:00
mm Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
net bpf: fix x64 JIT code generation for jmp to 1st insn 2019-08-01 13:12:09 -07:00
oprofile
pci dma-mapping updates for 5.4: 2019-09-19 13:27:23 -07:00
platform efi/x86: Do not clean dummy variable in kexec path 2019-10-07 15:24:36 +02:00
power Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-09-17 12:04:39 -07:00
purgatory Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-09-28 13:37:41 -07:00
ras RAS/CEC: Add CONFIG_RAS_CEC_DEBUG and move CEC debug features there 2019-06-08 17:39:24 +02:00
realmode x86/realmode: Remove trampoline_status 2019-07-22 11:30:18 +02:00
tools Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-07-08 17:34:44 -07:00
um um: Use real DMA barriers 2019-09-15 21:37:14 +02:00
video treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
xen xen: fixes for 5.4-rc3 2019-10-12 14:11:21 -07:00
.gitignore
Kbuild treewide: Add SPDX license identifier - Kbuild 2019-05-30 11:32:33 -07:00
Kconfig Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
Kconfig.cpu x86/cpu: Create Zhaoxin processors architecture support file 2019-06-22 11:45:57 +02:00
Kconfig.debug x86, perf: Fix the dependency of the x86 insn decoder selftest 2019-09-02 20:05:58 +02:00
Makefile x86/build: Add -Wnoaddress-of-packed-member to REALMODE_CFLAGS, to silence GCC9 build warning 2019-08-28 17:31:31 +02:00
Makefile_32.cpu
Makefile.um