[PATCH v5 01/51] x86/apic: Provide helpers to set local APIC timer period in hz and khz

[Sean Christopherson <seanjc@xxxxxxxxxx>]

Add and use APIs to set the local APIC timer period instead of open coding
the subtle HZ math in a all external callers, and make lapic_timer_period
local to apic.c.  Provide APIs to specify the frequency in both hertz and
kilohertz so that Hyper-V and VMware code aren't forced to lose precision.

Opportunistically use mul_u64_u32_div() to harden against the possibility
that the period in Khz is greater than 4294967, i.e. if the APIC timer runs
at ~4.29 GHz.  As pointed out by Sashiko, 4294968 * 1000 == 0x1_000002c0,
and thus a Khz period of 4294968 would silently overflow the 32-bit
unsigned integer used by most callers.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/x86/include/asm/apic.h    |  3 ++-
 arch/x86/kernel/apic/apic.c    | 12 +++++++++++-
 arch/x86/kernel/cpu/mshyperv.c |  5 +----
 arch/x86/kernel/cpu/vmware.c   |  4 +---
 arch/x86/kernel/jailhouse.c    |  2 +-
 arch/x86/kernel/tsc.c          |  2 +-
 arch/x86/kernel/tsc_msr.c      |  2 +-
 7 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 9cd493d467d4..cd84a94688a2 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -63,7 +63,6 @@ extern int apic_verbosity;
 extern int local_apic_timer_c2_ok;
 
 extern bool apic_is_disabled;
-extern unsigned int lapic_timer_period;
 
 extern enum apic_intr_mode_id apic_intr_mode;
 enum apic_intr_mode_id {
@@ -138,6 +137,8 @@ void register_lapic_address(unsigned long address);
 extern void setup_boot_APIC_clock(void);
 extern void setup_secondary_APIC_clock(void);
 extern void lapic_update_tsc_freq(void);
+extern void apic_set_timer_period_hz(u64 period_hz, const char *source);
+extern void apic_set_timer_period_khz(u64 period_khz, const char *source);
 
 #ifdef CONFIG_X86_64
 static inline bool apic_force_enable(unsigned long addr)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index aa1e19979aa8..8d3d930576fd 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -176,7 +176,7 @@ static struct resource lapic_resource = {
 };
 
 /* Measured in ticks per HZ. */
-unsigned int lapic_timer_period = 0;
+static unsigned int lapic_timer_period;
 
 static void apic_pm_activate(void);
 
@@ -796,6 +796,16 @@ bool __init apic_needs_pit(void)
        return lapic_timer_period == 0;
 }
 
+void apic_set_timer_period_khz(u64 period_khz, const char *source)
+{
+       lapic_timer_period = mul_u64_u32_div(period_khz, 1000, HZ);
+}
+
+void apic_set_timer_period_hz(u64 period_hz, const char *source)
+{
+       lapic_timer_period = div_u64(period_hz, HZ);
+}
+
 static int __init calibrate_APIC_clock(void)
 {
        struct clock_event_device *levt = this_cpu_ptr(&lapic_events);
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 185d4f677ec0..87beecec76f0 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -646,10 +646,7 @@ static void __init ms_hyperv_init_platform(void)
                u64     hv_lapic_frequency;
 
                rdmsrq(HV_X64_MSR_APIC_FREQUENCY, hv_lapic_frequency);
-               hv_lapic_frequency = div_u64(hv_lapic_frequency, HZ);
-               lapic_timer_period = hv_lapic_frequency;
-               pr_info("Hyper-V: LAPIC Timer Frequency: %#x\n",
-                       lapic_timer_period);
+               apic_set_timer_period_hz(hv_lapic_frequency, "Hyper-V 
hypervisor");
        }
 
        register_nmi_handler(NMI_UNKNOWN, hv_nmi_unknown, NMI_FLAG_FIRST,
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 34b73573b108..36f779dd311d 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -424,9 +424,7 @@ static void __init vmware_platform_setup(void)
 
 #ifdef CONFIG_X86_LOCAL_APIC
                /* Skip lapic calibration since we know the bus frequency. */
-               lapic_timer_period = ecx / HZ;
-               pr_info("Host bus clock speed read from hypervisor : %u Hz\n",
-                       ecx);
+               apic_set_timer_period_hz(ecx, "VMware hypervisor");
 #endif
        } else {
                pr_warn("Failed to get TSC freq from the hypervisor\n");
diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
index f58ce9220e0f..f2d4ef89c085 100644
--- a/arch/x86/kernel/jailhouse.c
+++ b/arch/x86/kernel/jailhouse.c
@@ -65,7 +65,7 @@ static void jailhouse_get_wallclock(struct timespec64 *now)
 
 static void __init jailhouse_timer_init(void)
 {
-       lapic_timer_period = setup_data.v1.apic_khz * (1000 / HZ);
+       apic_set_timer_period_khz(setup_data.v1.apic_khz, "Jailhouse 
hypervisor");
 }
 
 static unsigned long jailhouse_get_tsc(void)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index ce10ae4b298b..f9ecc9256863 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -717,7 +717,7 @@ unsigned long native_calibrate_tsc(void)
         * lapic_timer_period here to avoid having to calibrate the APIC
         * timer later.
         */
-       lapic_timer_period = crystal_khz * 1000 / HZ;
+       apic_set_timer_period_khz(crystal_khz, "CPUID 0x15/0x16");
 #endif
 
        return crystal_khz * ebx_numerator / eax_denominator;
diff --git a/arch/x86/kernel/tsc_msr.c b/arch/x86/kernel/tsc_msr.c
index 48e6cc1cb017..7e990871e041 100644
--- a/arch/x86/kernel/tsc_msr.c
+++ b/arch/x86/kernel/tsc_msr.c
@@ -211,7 +211,7 @@ unsigned long cpu_khz_from_msr(void)
                pr_err("Error MSR_FSB_FREQ index %d is unknown\n", index);
 
 #ifdef CONFIG_X86_LOCAL_APIC
-       lapic_timer_period = (freq * 1000) / HZ;
+       apic_set_timer_period_khz(freq, "MSR_FSB_FREQ");
 #endif
 
        /*
-- 
2.55.0.rc0.799.gd6f94ed593-goog