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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Oct 2024 09:30:11.4275 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 5f67c8f8-7abf-463c-5a5a-08dce844f921 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL02EPF00021F69.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR12MB7962 Content-Type: text/plain; charset="utf-8" Although the kernel switches over to stable TSC clocksource instead of kvmclock, the scheduler still keeps on using kvmclock as the sched clock. This is due to kvm_sched_clock_init() updating the pv_sched_clock() unconditionally. Use the clock source enable/disable callbacks to initialize kvm_sched_clock_init() and update the pv_sched_clock(). As the clock selection happens in the stop machine context, schedule delayed work to update the static_call() Signed-off-by: Nikunj A Dadhania --- arch/x86/kernel/kvmclock.c | 34 +++++++++++++++++++++++++++++----- 1 file changed, 29 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 5b2c15214a6b..5cd3717e103b 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -21,6 +21,7 @@ #include #include #include +#include =20 static int kvmclock __initdata =3D 1; static int kvmclock_vsyscall __initdata =3D 1; @@ -148,12 +149,39 @@ bool kvm_check_and_clear_guest_paused(void) return ret; } =20 +static u64 (*old_pv_sched_clock)(void); + +static void enable_kvm_sc_work(struct work_struct *work) +{ + u8 flags; + + old_pv_sched_clock =3D static_call_query(pv_sched_clock); + flags =3D pvclock_read_flags(&hv_clock_boot[0].pvti); + kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT); +} + +static DECLARE_DELAYED_WORK(enable_kvm_sc, enable_kvm_sc_work); + +static void disable_kvm_sc_work(struct work_struct *work) +{ + if (old_pv_sched_clock) + paravirt_set_sched_clock(old_pv_sched_clock); +} +static DECLARE_DELAYED_WORK(disable_kvm_sc, disable_kvm_sc_work); + static int kvm_cs_enable(struct clocksource *cs) { vclocks_set_used(VDSO_CLOCKMODE_PVCLOCK); + schedule_delayed_work(&enable_kvm_sc, 0); + return 0; } =20 +static void kvm_cs_disable(struct clocksource *cs) +{ + schedule_delayed_work(&disable_kvm_sc, 0); +} + static struct clocksource kvm_clock =3D { .name =3D "kvm-clock", .read =3D kvm_clock_get_cycles, @@ -162,6 +190,7 @@ static struct clocksource kvm_clock =3D { .flags =3D CLOCK_SOURCE_IS_CONTINUOUS, .id =3D CSID_X86_KVM_CLK, .enable =3D kvm_cs_enable, + .disable =3D kvm_cs_disable, }; =20 static void kvm_register_clock(char *txt) @@ -287,8 +316,6 @@ static int kvmclock_setup_percpu(unsigned int cpu) =20 void __init kvmclock_init(void) { - u8 flags; - if (!kvm_para_available() || !kvmclock) return; =20 @@ -317,9 +344,6 @@ void __init kvmclock_init(void) if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); =20 - flags =3D pvclock_read_flags(&hv_clock_boot[0].pvti); - kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT); - x86_platform.calibrate_tsc =3D kvm_get_tsc_khz; x86_platform.calibrate_cpu =3D kvm_get_tsc_khz; x86_platform.get_wallclock =3D kvm_get_wallclock; --=20 2.34.1