[GIT PULL] x86 fixes

Ingo Molnar
2023-10-28T10:51:05Z

Linus,

Please pull the latest x86/urgent git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2023-10-28

# HEAD: bd94d86f490b70c58b3fc5739328a53ad4b18d86 x86/tsc: Defer marking TSC unstable to a worker

Misc fixes:

- Fix a possible CPU hotplug deadlock bug caused by the new
TSC synchronization code.

- Fix a legacy PIC discovery bug that results in device troubles on
affected systems, such as non-working keybards, etc.

- Add a new Intel CPU model number to <asm/intel-family.h>.

Thanks,

Ingo

------------------>
Thomas Gleixner (2):
x86/i8259: Skip probing when ACPI/MADT advertises PCAT compatibility
x86/tsc: Defer marking TSC unstable to a worker

Tony Luck (1):
x86/cpu: Add model number for Intel Arrow Lake mobile processor

arch/x86/include/asm/i8259.h | 2 ++
arch/x86/include/asm/intel-family.h | 2 ++
arch/x86/kernel/acpi/boot.c | 3 +++
arch/x86/kernel/i8259.c | 38 +++++++++++++++++++++++++++++--------
arch/x86/kernel/tsc_sync.c | 10 +++++++++-
5 files changed, 46 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/i8259.h b/arch/x86/include/asm/i8259.h
index 637fa1df3512..c715097e92fd 100644
--- a/arch/x86/include/asm/i8259.h
+++ b/arch/x86/include/asm/i8259.h
@@ -69,6 +69,8 @@ struct legacy_pic {
void (*make_irq)(unsigned int irq);
};

+void legacy_pic_pcat_compat(void);
+
extern struct legacy_pic *legacy_pic;
extern struct legacy_pic null_legacy_pic;

diff --git a/arch/x86/include/asm/intel-family.h b/arch/x86/include/asm/intel-family.h
index 5fcd85fd64fd..197316121f04 100644
--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -27,6 +27,7 @@
* _X - regular server parts
* _D - micro server parts
* _N,_P - other mobile parts
+ * _H - premium mobile parts
* _S - other client parts
*
* Historical OPTDIFFs:
@@ -124,6 +125,7 @@
#define INTEL_FAM6_METEORLAKE 0xAC
#define INTEL_FAM6_METEORLAKE_L 0xAA

+#define INTEL_FAM6_ARROWLAKE_H 0xC5
#define INTEL_FAM6_ARROWLAKE 0xC6

#define INTEL_FAM6_LUNARLAKE_M 0xBD
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 2a0ea38955df..c55c0ef47a18 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -148,6 +148,9 @@ static int __init acpi_parse_madt(struct acpi_table_header *table)
pr_debug("Local APIC address 0x%08x\n", madt->address);
}

+ if (madt->flags & ACPI_MADT_PCAT_COMPAT)
+ legacy_pic_pcat_compat();
+
/* ACPI 6.3 and newer support the online capable bit. */
if (acpi_gbl_FADT.header.revision > 6 ||
(acpi_gbl_FADT.header.revision == 6 &&
diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c
index 30a55207c000..c20d1832c481 100644
--- a/arch/x86/kernel/i8259.c
+++ b/arch/x86/kernel/i8259.c
@@ -32,6 +32,7 @@
*/
static void init_8259A(int auto_eoi);

+static bool pcat_compat __ro_after_init;
static int i8259A_auto_eoi;
DEFINE_RAW_SPINLOCK(i8259A_lock);

@@ -299,15 +300,32 @@ static void unmask_8259A(void)

static int probe_8259A(void)
{
+ unsigned char new_val, probe_val = ~(1 << PIC_CASCADE_IR);
unsigned long flags;
- unsigned char probe_val = ~(1 << PIC_CASCADE_IR);
- unsigned char new_val;
+
/*
- * Check to see if we have a PIC.
- * Mask all except the cascade and read
- * back the value we just wrote. If we don't
- * have a PIC, we will read 0xff as opposed to the
- * value we wrote.
+ * If MADT has the PCAT_COMPAT flag set, then do not bother probing
+ * for the PIC. Some BIOSes leave the PIC uninitialized and probing
+ * fails.
+ *
+ * Right now this causes problems as quite some code depends on
+ * nr_legacy_irqs() > 0 or has_legacy_pic() == true. This is silly
+ * when the system has an IO/APIC because then PIC is not required
+ * at all, except for really old machines where the timer interrupt
+ * must be routed through the PIC. So just pretend that the PIC is
+ * there and let legacy_pic->init() initialize it for nothing.
+ *
+ * Alternatively this could just try to initialize the PIC and
+ * repeat the probe, but for cases where there is no PIC that's
+ * just pointless.
+ */
+ if (pcat_compat)
+ return nr_legacy_irqs();
+
+ /*
+ * Check to see if we have a PIC. Mask all except the cascade and
+ * read back the value we just wrote. If we don't have a PIC, we
+ * will read 0xff as opposed to the value we wrote.
*/
raw_spin_lock_irqsave(&i8259A_lock, flags);

@@ -429,5 +447,9 @@ static int __init i8259A_init_ops(void)

return 0;
}
-
device_initcall(i8259A_init_ops);
+
+void __init legacy_pic_pcat_compat(void)
+{
+ pcat_compat = true;
+}
diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index bbc440c93e08..1123ef3ccf90 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -15,6 +15,7 @@
* ( The serial nature of the boot logic and the CPU hotplug lock
* protects against more than 2 CPUs entering this code. )
*/
+#include <linux/workqueue.h>
#include <linux/topology.h>
#include <linux/spinlock.h>
#include <linux/kernel.h>
@@ -342,6 +343,13 @@ static inline unsigned int loop_timeout(int cpu)
return (cpumask_weight(topology_core_cpumask(cpu)) > 1) ? 2 : 20;
}

+static void tsc_sync_mark_tsc_unstable(struct work_struct *work)
+{
+ mark_tsc_unstable("check_tsc_sync_source failed");
+}
+
+static DECLARE_WORK(tsc_sync_work, tsc_sync_mark_tsc_unstable);
+
/*
* The freshly booted CPU initiates this via an async SMP function call.
*/
@@ -395,7 +403,7 @@ static void check_tsc_sync_source(void *__cpu)
"turning off TSC clock.\n", max_warp);
if (random_warps)
pr_warn("TSC warped randomly between CPUs\n");
- mark_tsc_unstable("check_tsc_sync_source failed");
+ schedule_work(&tsc_sync_work);
}

/*