linux-stable.git/arch/x86/kernel/kvmclock.c, branch linux-5.4.y

x86/kvm: Do not try to disable kvmclock if it was not enabled

2024-01-25T22:34:30+00:00

commit 1c6d984f523f67ecfad1083bb04c55d91977bb15 upstream.

kvm_guest_cpu_offline() tries to disable kvmclock regardless if it is
present in the VM. It leads to write to a MSR that doesn't exist on some
configurations, namely in TDX guest:

	unchecked MSR access error: WRMSR to 0x12 (tried to write 0x0000000000000000)
	at rIP: 0xffffffff8110687c (kvmclock_disable+0x1c/0x30)

kvmclock enabling is gated by CLOCKSOURCE and CLOCKSOURCE2 KVM paravirt
features.

Do not disable kvmclock if it was not enabled.

Signed-off-by: Kirill A. Shutemov 
Fixes: c02027b5742b ("x86/kvm: Disable kvmclock on all CPUs on shutdown")
Reviewed-by: Sean Christopherson 
Reviewed-by: Vitaly Kuznetsov 
Cc: Paolo Bonzini 
Cc: Wanpeng Li 
Cc: stable@vger.kernel.org
Message-Id: <20231205004510.27164-6-kirill.shutemov@linux.intel.com>
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

x86/kvmclock: Move this_cpu_pvti into kvmclock.h

2021-10-06T13:42:31+00:00

commit ad9af930680bb396c87582edc172b3a7cf2a3fbf upstream.

There're other modules might use hv_clock_per_cpu variable like ptp_kvm,
so move it into kvmclock.h and export the symbol to make it visiable to
other modules.

Signed-off-by: Zelin Deng 
Cc: 
Message-Id: <1632892429-101194-2-git-send-email-zelin.deng@linux.alibaba.com>
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

x86/kvm: Disable all PV features on crash

2021-06-10T11:37:16+00:00

commit 3d6b84132d2a57b5a74100f6923a8feb679ac2ce upstream.

Crash shutdown handler only disables kvmclock and steal time, other PV
features remain active so we risk corrupting memory or getting some
side-effects in kdump kernel. Move crash handler to kvm.c and unify
with CPU offline.

Signed-off-by: Vitaly Kuznetsov 
Message-Id: <20210414123544.1060604-5-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini 
Signed-off-by: Krzysztof Kozlowski 
Signed-off-by: Greg Kroah-Hartman

x86/kvm: Disable kvmclock on all CPUs on shutdown

2021-06-10T11:37:16+00:00

commit c02027b5742b5aa804ef08a4a9db433295533046 upstream.

Currenly, we disable kvmclock from machine_shutdown() hook and this
only happens for boot CPU. We need to disable it for all CPUs to
guard against memory corruption e.g. on restore from hibernate.

Note, writing '0' to kvmclock MSR doesn't clear memory location, it
just prevents hypervisor from updating the location so for the short
while after write and while CPU is still alive, the clock remains usable
and correct so we don't need to switch to some other clocksource.

Signed-off-by: Vitaly Kuznetsov 
Message-Id: <20210414123544.1060604-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini 
Signed-off-by: Andrea Righi 
Signed-off-by: Krzysztof Kozlowski 
Signed-off-by: Greg Kroah-Hartman

x86: kvmguest: use TSC clocksource if invariant TSC is exposed

2019-02-20T21:48:52+00:00

The invariant TSC bit has the following meaning:

"The time stamp counter in newer processors may support an enhancement,
referred to as invariant TSC. Processor's support for invariant TSC
is indicated by CPUID.80000007H:EDX[8]. The invariant TSC will run
at a constant rate in all ACPI P-, C-. and T-states. This is the
architectural behavior moving forward. On processors with invariant TSC
support, the OS may use the TSC for wall clock timer services (instead
of ACPI or HPET timers). TSC reads are much more efficient and do not
incur the overhead associated with a ring transition or access to a
platform resource."

IOW, TSC does not change frequency. In such case, and with
TSC scaling hardware available to handle migration, it is possible
to use the TSC clocksource directly, whose system calls are
faster.

Reduce the rating of kvmclock clocksource to allow TSC clocksource
to be the default if invariant TSC is exposed.

Signed-off-by: Marcelo Tosatti 

v2: Use feature bits and tsc_unstable() check (Sean Christopherson)
Signed-off-by: Paolo Bonzini

x86/kvmclock: set offset for kvm unstable clock

2019-02-20T21:48:19+00:00

VMs may show incorrect uptime and dmesg printk offsets on hypervisors with
unstable clock. The problem is produced when VM is rebooted without exiting
from qemu.

The fix is to calculate clock offset not only for stable clock but for
unstable clock as well, and use kvm_sched_clock_read() which substracts
the offset for both clocks.

This is safe, because pvclock_clocksource_read() does the right thing and
makes sure that clock always goes forward, so once offset is calculated
with unstable clock, we won't get new reads that are smaller than offset,
and thus won't get negative results.

Thank you Jon DeVree for helping to reproduce this issue.

Fixes: 857baa87b642 ("sched/clock: Enable sched clock early")
Cc: stable@vger.kernel.org
Reported-by: Dominique Martinet 
Signed-off-by: Pavel Tatashin 
Signed-off-by: Paolo Bonzini

x86/kvmclock: convert to SPDX identifiers

2018-12-21T10:28:25+00:00

Update the verbose license text with the matching SPDX
license identifier.

Signed-off-by: Peng Hao 
[Changed deprecated GPL-2.0+ to GPL-2.0-or-later. - Radim]
Signed-off-by: Radim Krčmář

Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-10-23T16:54:58+00:00

Pull x86 paravirt updates from Ingo Molnar:
 "Two main changes:

   - Remove no longer used parts of the paravirt infrastructure and put
     large quantities of paravirt ops under a new config option
     PARAVIRT_XXL=y, which is selected by XEN_PV only. (Joergen Gross)

   - Enable PV spinlocks on Hyperv (Yi Sun)"

* 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/hyperv: Enable PV qspinlock for Hyper-V
  x86/hyperv: Add GUEST_IDLE_MSR support
  x86/paravirt: Clean up native_patch()
  x86/paravirt: Prevent redefinition of SAVE_FLAGS macro
  x86/xen: Make xen_reservation_lock static
  x86/paravirt: Remove unneeded mmu related paravirt ops bits
  x86/paravirt: Move the Xen-only pv_mmu_ops under the PARAVIRT_XXL umbrella
  x86/paravirt: Move the pv_irq_ops under the PARAVIRT_XXL umbrella
  x86/paravirt: Move the Xen-only pv_cpu_ops under the PARAVIRT_XXL umbrella
  x86/paravirt: Move items in pv_info under PARAVIRT_XXL umbrella
  x86/paravirt: Introduce new config option PARAVIRT_XXL
  x86/paravirt: Remove unused paravirt bits
  x86/paravirt: Use a single ops structure
  x86/paravirt: Remove clobbers from struct paravirt_patch_site
  x86/paravirt: Remove clobbers parameter from paravirt patch functions
  x86/paravirt: Make paravirt_patch_call() and paravirt_patch_jmp() static
  x86/xen: Add SPDX identifier in arch/x86/xen files
  x86/xen: Link platform-pci-unplug.o only if CONFIG_XEN_PVHVM
  x86/xen: Move pv specific parts of arch/x86/xen/mmu.c to mmu_pv.c
  x86/xen: Move pv irq related functions under CONFIG_XEN_PV umbrella

x86/kvm: Use __bss_decrypted attribute in shared variables

2018-09-15T18:48:46+00:00

The recent removal of the memblock dependency from kvmclock caused a SEV
guest regression because the wall_clock and hv_clock_boot variables are
no longer mapped decrypted when SEV is active.

Use the __bss_decrypted attribute to put the static wall_clock and
hv_clock_boot in the .bss..decrypted section so that they are mapped
decrypted during boot.

In the preparatory stage of CPU hotplug, the per-cpu pvclock data pointer
assigns either an element of the static array or dynamically allocated
memory for the pvclock data pointer. The static array are now mapped
decrypted but the dynamically allocated memory is not mapped decrypted.
However, when SEV is active this memory range must be mapped decrypted.

Add a function which is called after the page allocator is up, and
allocate memory for the pvclock data pointers for the all possible cpus.
Map this memory range as decrypted when SEV is active.

Fixes: 368a540e0232 ("x86/kvmclock: Remove memblock dependency")
Suggested-by: Thomas Gleixner 
Signed-off-by: Brijesh Singh 
Signed-off-by: Thomas Gleixner 
Cc: Tom Lendacky 
Cc: Borislav Petkov 
Cc: "H. Peter Anvin" 
Cc: Paolo Bonzini 
Cc: Sean Christopherson 
Cc: "Radim Krčmář" 
Cc: kvm@vger.kernel.org
Link: https://lkml.kernel.org/r/1536932759-12905-3-git-send-email-brijesh.singh@amd.com

x86/paravirt: Use a single ops structure

2018-09-03T14:50:35+00:00

Instead of using six globally visible paravirt ops structures combine
them in a single structure, keeping the original structures as
sub-structures.

This avoids the need to assemble struct paravirt_patch_template at
runtime on the stack each time apply_paravirt() is being called (i.e.
when loading a module).

[ tglx: Made the struct and the initializer tabular for readability sake ]

Signed-off-by: Juergen Gross 
Signed-off-by: Thomas Gleixner 
Cc: xen-devel@lists.xenproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: akataria@vmware.com
Cc: rusty@rustcorp.com.au
Cc: boris.ostrovsky@oracle.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/20180828074026.820-9-jgross@suse.com