linux-stable/tools
Paolo Bonzini 0c899c25d7 KVM: x86: do not attempt TSC synchronization on guest writes
KVM special-cases writes to MSR_IA32_TSC so that all CPUs have
the same base for the TSC.  This logic is complicated, and we
do not want it to have any effect once the VM is started.

In particular, if any guest started to synchronize its TSCs
with writes to MSR_IA32_TSC rather than MSR_IA32_TSC_ADJUST,
the additional effect of kvm_write_tsc code would be uncharted
territory.

Therefore, this patch makes writes to MSR_IA32_TSC behave
essentially the same as writes to MSR_IA32_TSC_ADJUST when
they come from the guest.  A new selftest (which passes
both before and after the patch) checks the current semantics
of writes to MSR_IA32_TSC and MSR_IA32_TSC_ADJUST originating
from both the host and the guest.

Upcoming work to remove the special side effects
of host-initiated writes to MSR_IA32_TSC and MSR_IA32_TSC_ADJUST
will be able to build onto this test, adjusting the host side
to use the new APIs and achieve the same effect.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-09-28 07:59:52 -04:00
..
accounting
arch tools headers kvm s390: Sync headers with the kernel sources 2020-08-12 08:52:32 -03:00
bootconfig tools/bootconfig: Add testcases for value override operator 2020-08-03 16:22:29 -04:00
bpf tools/resolve_btfids: Fix sections with wrong alignment 2020-08-20 14:17:20 -07:00
build perf build-ids: Fall back to debuginfod query if debuginfo not found 2020-08-14 09:51:14 -03:00
cgroup tools/cgroup: add memcg_slabinfo.py tool 2020-08-07 11:33:25 -07:00
debugging
edid
firewire
firmware
gpio tools: gpio: fix spurious close warning in gpio-event-mon 2020-07-12 10:22:01 +02:00
hv
iio
include perf tools fixes for v5.9: 2020-09-01 19:36:52 -07:00
io_uring
kvm/kvm_stat
laptop
leds
lib libtraceevent: Fix build warning on 32-bit arches 2020-09-03 15:45:15 -03:00
memory-model These were the main changes in this cycle: 2020-08-03 14:39:35 -07:00
nfsd
objtool Misc updates: 2020-08-03 14:45:33 -07:00
pci
pcmcia
perf perf tools: Add bpf image check to __map__is_kmodule 2020-09-03 16:04:46 -03:00
power ACPI updates for 5.9-rc1 2020-08-03 20:37:22 -07:00
scripts
spi
testing KVM: x86: do not attempt TSC synchronization on guest writes 2020-09-28 07:59:52 -04:00
thermal/tmon
time
usb tools: usb: move to tools buildsystem 2020-08-19 14:11:44 +02:00
virtio virtio: fixes, features 2020-08-11 14:34:17 -07:00
vm
wmi
Makefile bpf: Compile resolve_btfids tool at kernel compilation start 2020-07-13 10:42:02 -07:00