diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2024-09-17 15:27:01 +0200 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2024-09-17 15:27:01 +0200 |
commit | fc1dc0d50780a9b215322bcc315f07ad8e4c6c13 (patch) | |
tree | 79abf1631a4e1fd597a10805972147d8db18c761 /arch/x86 | |
parent | b50753547453613eb5d0fada99d55583852c42df (diff) | |
parent | e7ff4ebffe3bedf55560ef861d80f6500ff0d76f (diff) |
Merge tag 'x86-timers-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 timer updates from Thomas Gleixner:
- Use the topology information of number of packages for making the
decision about TSC trust instead of using the number of online nodes
which is not reflecting the real topology.
- Stop the PIT timer 0 when its not in use as to stop pointless
emulation in the VMM.
- Fix the PIT timer stop sequence for timer 0 so it truly stops both
real hardware and buggy VMM emulations.
* tag 'x86-timers-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/tsc: Check for sockets instead of CPUs to make code match comment
clockevents/drivers/i8253: Fix stop sequence for timer 0
x86/i8253: Disable PIT timer 0 when not in use
x86/tsc: Use topology_max_packages() to get package number
Diffstat (limited to 'arch/x86')
-rw-r--r-- | arch/x86/kernel/cpu/mshyperv.c | 11 | ||||
-rw-r--r-- | arch/x86/kernel/i8253.c | 11 | ||||
-rw-r--r-- | arch/x86/kernel/tsc.c | 10 |
3 files changed, 13 insertions, 19 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index ead967479fa6..d18078834ded 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -16,7 +16,6 @@ #include <linux/interrupt.h> #include <linux/irq.h> #include <linux/kexec.h> -#include <linux/i8253.h> #include <linux/random.h> #include <asm/processor.h> #include <asm/hypervisor.h> @@ -537,16 +536,6 @@ static void __init ms_hyperv_init_platform(void) if (efi_enabled(EFI_BOOT)) x86_platform.get_nmi_reason = hv_get_nmi_reason; - /* - * Hyper-V VMs have a PIT emulation quirk such that zeroing the - * counter register during PIT shutdown restarts the PIT. So it - * continues to interrupt @18.2 HZ. Setting i8253_clear_counter - * to false tells pit_shutdown() not to zero the counter so that - * the PIT really is shutdown. Generation 2 VMs don't have a PIT, - * and setting this value has no effect. - */ - i8253_clear_counter_on_shutdown = false; - #if IS_ENABLED(CONFIG_HYPERV) if ((hv_get_isolation_type() == HV_ISOLATION_TYPE_VBS) || ms_hyperv.paravisor_present) diff --git a/arch/x86/kernel/i8253.c b/arch/x86/kernel/i8253.c index 2b7999a1a50a..80e262bb627f 100644 --- a/arch/x86/kernel/i8253.c +++ b/arch/x86/kernel/i8253.c @@ -8,6 +8,7 @@ #include <linux/timex.h> #include <linux/i8253.h> +#include <asm/hypervisor.h> #include <asm/apic.h> #include <asm/hpet.h> #include <asm/time.h> @@ -39,9 +40,15 @@ static bool __init use_pit(void) bool __init pit_timer_init(void) { - if (!use_pit()) + if (!use_pit()) { + /* + * Don't just ignore the PIT. Ensure it's stopped, because + * VMMs otherwise steal CPU time just to pointlessly waggle + * the (masked) IRQ. + */ + clockevent_i8253_disable(); return false; - + } clockevent_i8253_init(true); global_clock_event = &i8253_clockevent; return true; diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index d4462fb26299..dfe6847fd99e 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -28,6 +28,7 @@ #include <asm/apic.h> #include <asm/cpu_device_id.h> #include <asm/i8259.h> +#include <asm/topology.h> #include <asm/uv/uv.h> unsigned int __read_mostly cpu_khz; /* TSC clocks / usec, not used here */ @@ -1253,15 +1254,12 @@ static void __init check_system_tsc_reliable(void) * - TSC which does not stop in C-States * - the TSC_ADJUST register which allows to detect even minimal * modifications - * - not more than two sockets. As the number of sockets cannot be - * evaluated at the early boot stage where this has to be - * invoked, check the number of online memory nodes as a - * fallback solution which is an reasonable estimate. + * - not more than four packages */ if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && boot_cpu_has(X86_FEATURE_NONSTOP_TSC) && boot_cpu_has(X86_FEATURE_TSC_ADJUST) && - nr_online_nodes <= 4) + topology_max_packages() <= 4) tsc_disable_clocksource_watchdog(); } @@ -1290,7 +1288,7 @@ int unsynchronized_tsc(void) */ if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { /* assume multi socket systems are not synchronized: */ - if (num_possible_cpus() > 1) + if (topology_max_packages() > 1) return 1; } |