From 27d2afa3b4eab5fb2a03b6ad8b74a3a700e92dce Mon Sep 17 00:00:00 2001 From: Christophe JAILLET Date: Sun, 19 Oct 2025 10:18:20 +0200 Subject: [PATCH 1/2] x86/ioapic: Simplify mp_irqdomain_alloc() slightly The IRQ return value of irq_find_mapping() is only tested for existence, not used for anything else. So, this call can be replaced by a slightly simpler irq_resolve_mapping() call, which reduces generated code size a bit (x86-64 allmodconfig): text data bss dec hex filename 82142 38633 18048 138823 21e47 arch/x86/kernel/apic/io_apic.o.before 81932 38633 18048 138613 21d75 arch/x86/kernel/apic/io_apic.o.after [ mingo: Fixed & simplified the changelog ] Signed-off-by: Christophe JAILLET Signed-off-by: Ingo Molnar Cc: Thomas Gleixner Cc: kernel-janitors@vger.kernel.org Link: https://patch.msgid.link/cb3a4968538637aac3a5ae4f5ecc4f5eb43376ea.1760861877.git.christophe.jaillet@wanadoo.fr --- arch/x86/kernel/apic/io_apic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 5ba2feb2c04c..1e0442e867b1 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -2864,7 +2864,7 @@ int mp_irqdomain_alloc(struct irq_domain *domain, unsigned int virq, ioapic = mp_irqdomain_ioapic_idx(domain); pin = info->ioapic.pin; - if (irq_find_mapping(domain, (irq_hw_number_t)pin) > 0) + if (irq_resolve_mapping(domain, (irq_hw_number_t)pin)) return -EEXIST; data = kzalloc(sizeof(*data), GFP_KERNEL); From ed4f9638d905a97cebd49ecea85cc9b706b73761 Mon Sep 17 00:00:00 2001 From: Julian Stecklina Date: Sat, 30 Oct 2021 16:21:48 +0200 Subject: [PATCH 2/2] x86/apic: Fix frequency in apic=verbose log output When apic=verbose is specified, the LAPIC timer calibration prints its results to the console. At least while debugging virtualization code, the CPU and bus frequencies are printed incorrectly. Specifically, for a 1.7 GHz CPU with 1 GHz bus frequency and HZ=1000, the log includes a superfluous 0 after the period: ..... calibration result: 999978 ..... CPU clock speed is 1696.0783 MHz. ..... host bus clock speed is 999.0978 MHz. Looking at the code, this only worked as intended for HZ=100. After the fix, the correct frequency is printed: ..... calibration result: 999828 ..... CPU clock speed is 1696.507 MHz. ..... host bus clock speed is 999.828 MHz. There is no functional change to the LAPIC calibration here, beyond the printing format changes. [ bp: - Massage commit message - Figures it should apply this patch about ~4 years later - Massage it into the current code ] Suggested-by: Markus Napierkowski Signed-off-by: Julian Stecklina Signed-off-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20211030142148.143261-1-js@alien8.de --- arch/x86/kernel/apic/apic.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 680d305589a3..ca1c8b70ac44 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -173,6 +173,7 @@ static struct resource lapic_resource = { .flags = IORESOURCE_MEM | IORESOURCE_BUSY, }; +/* Measured in ticks per HZ. */ unsigned int lapic_timer_period = 0; static void apic_pm_activate(void); @@ -792,6 +793,7 @@ static int __init calibrate_APIC_clock(void) { struct clock_event_device *levt = this_cpu_ptr(&lapic_events); u64 tsc_perj = 0, tsc_start = 0; + long delta_tsc_khz, bus_khz; unsigned long jif_start; unsigned long deltaj; long delta, deltatsc; @@ -894,14 +896,15 @@ static int __init calibrate_APIC_clock(void) apic_pr_verbose("..... calibration result: %u\n", lapic_timer_period); if (boot_cpu_has(X86_FEATURE_TSC)) { - apic_pr_verbose("..... CPU clock speed is %ld.%04ld MHz.\n", - (deltatsc / LAPIC_CAL_LOOPS) / (1000000 / HZ), - (deltatsc / LAPIC_CAL_LOOPS) % (1000000 / HZ)); + delta_tsc_khz = (deltatsc * HZ) / (1000 * LAPIC_CAL_LOOPS); + + apic_pr_verbose("..... CPU clock speed is %ld.%03ld MHz.\n", + delta_tsc_khz / 1000, delta_tsc_khz % 1000); } - apic_pr_verbose("..... host bus clock speed is %u.%04u MHz.\n", - lapic_timer_period / (1000000 / HZ), - lapic_timer_period % (1000000 / HZ)); + bus_khz = (long)lapic_timer_period * HZ / 1000; + apic_pr_verbose("..... host bus clock speed is %ld.%03ld MHz.\n", + bus_khz / 1000, bus_khz % 1000); /* * Do a sanity check on the APIC calibration result