Maciej S. Szmigiero 2dc652961d target/i386: Reset TSCs of parked vCPUs too on VM reset ... Since commit 5286c36622 ("target/i386: properly reset TSC on reset") QEMU writes the special value of "1" to each online vCPU TSC on VM reset to reset it. However parked vCPUs don't get that handling and due to that their TSCs get desynchronized when the VM gets reset. This in turn causes KVM to turn off PVCLOCK_TSC_STABLE_BIT in its exported PV clock. Note that KVM has no understanding of vCPU being currently parked. Without PVCLOCK_TSC_STABLE_BIT the sched clock is marked unstable in the guest's kvm_sched_clock_init(). This causes a performance regressions to show in some tests. Fix this issue by writing the special value of "1" also to TSCs of parked vCPUs on VM reset. Reproducing the issue: 1) Boot a VM with "-smp 2,maxcpus=3" or similar 2) device_add host-x86_64-cpu,id=vcpu,node-id=0,socket-id=0,core-id=2,thread-id=0 3) Wait a few seconds 4) device_del vcpu 5) Inside the VM run: # echo "t" >/proc/sysrq-trigger; dmesg | grep sched_clock_stable Observe the sched_clock_stable() value is 1. 6) Reboot the VM 7) Once the VM boots once again run inside it: # echo "t" >/proc/sysrq-trigger; dmesg | grep sched_clock_stable Observe the sched_clock_stable() value is now 0. Fixes: 5286c36622 ("target/i386: properly reset TSC on reset") Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com> Link: https://lore.kernel.org/r/5a605a88e9a231386dc803c60f5fed9b48108139.1734014926.git.maciej.szmigiero@oracle.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> (cherry picked from commit 3f2a05b31ee9ce2ddb6c75a9bc3f5e7f7af9a76f) Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>		2024-12-22 11:18:15 +03:00
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hvf	hvf: arm: Implement and use hvf_get_physical_address_range	2024-09-13 15:31:47 +01:00
kvm	target/i386: Reset TSCs of parked vCPUs too on VM reset	2024-12-22 11:18:15 +03:00
qtest	qtest: move qtest_{get, set}_virtual_clock to accel/qtest/qtest.c	2024-06-24 10:14:56 +01:00
stubs	accel: Restrict probe_access*() functions to TCG	2024-07-23 18:08:44 +02:00
tcg	tcg: Reset free_temps before tcg_optimize	2024-12-13 15:51:03 +03:00
xen	hw/xen: Extract 'xen_igd.h' from 'xen_pt.h'	2024-03-09 18:51:45 +01:00
Kconfig	i386: xen: fix compilation --without-default-devices	2024-02-16 13:56:09 +01:00
accel-blocker.c	include: Move QemuLockCnt APIs to their own header	2024-10-15 15:16:17 +01:00
accel-system.c	accel: remove dead statement and useless assertion	2024-10-31 18:28:32 +01:00
accel-system.h	accel: Rename accel_init_ops_interfaces() to include 'system'	2024-01-19 12:28:59 +01:00
accel-target.c	accel: Rename accel_init_ops_interfaces() to include 'system'	2024-01-19 12:28:59 +01:00
accel-user.c	accel: extend AccelState and AccelClass to user-mode	2021-02-05 10:24:15 -10:00
dummy-cpus.c	cpu: move Qemu[Thread|Cond] setup into common code	2024-06-04 10:02:39 +02:00
meson.build	accel: Rename accel_softmmu* -> accel_system*	2023-10-07 19:02:57 +02:00