Re: [patch V2 50/58] x86/apic: Provide common init infrastructure

From: Juergen Gross
Date: Mon Jul 31 2023 - 07:31:58 EST

On 24.07.23 15:35, Thomas Gleixner wrote:
In preparation for converting the hotpath APIC callbacks to static keys,
provide common initialization inforastructure.

Lift apic_install_drivers() from probe_64.c and convert all places which
switch the apic instance by storing the pointer to use apic_install_driver()
as a first step.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/include/asm/apic.h | 2 +
arch/x86/kernel/apic/Makefile | 2 -
arch/x86/kernel/apic/apic.c | 31 -----------------------
arch/x86/kernel/apic/apic_flat_64.c | 6 ----
arch/x86/kernel/apic/bigsmp_32.c | 6 +---
arch/x86/kernel/apic/init.c | 47 ++++++++++++++++++++++++++++++++++++
arch/x86/kernel/apic/probe_32.c | 5 +--
arch/x86/kernel/apic/probe_64.c | 13 ---------
arch/x86/xen/apic.c | 10 ++-----
9 files changed, 59 insertions(+), 63 deletions(-)

--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -344,6 +344,8 @@ extern int lapic_can_unplug_cpu(void);
#ifdef CONFIG_X86_LOCAL_APIC
+void __init apic_install_driver(struct apic *driver);
+
static inline u32 apic_read(u32 reg)
{
return apic->read(reg);
--- a/arch/x86/kernel/apic/Makefile
+++ b/arch/x86/kernel/apic/Makefile
@@ -7,7 +7,7 @@
# In particualr, smp_apic_timer_interrupt() is called in random places.
KCOV_INSTRUMENT := n
-obj-$(CONFIG_X86_LOCAL_APIC) += apic.o apic_common.o apic_noop.o ipi.o vector.o
+obj-$(CONFIG_X86_LOCAL_APIC) += apic.o apic_common.o apic_noop.o ipi.o vector.o init.o
obj-y += hw_nmi.o
obj-$(CONFIG_X86_IO_APIC) += io_apic.o
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -236,8 +236,7 @@ static int modern_apic(void)
*/
static void __init apic_disable(void)
{
- pr_info("APIC: switched to apic NOOP\n");
- apic = &apic_noop;
+ apic_install_driver(&apic_noop);
}
void native_apic_icr_write(u32 low, u32 id)
@@ -2486,34 +2485,6 @@ u32 x86_msi_msg_get_destid(struct msi_ms
}
EXPORT_SYMBOL_GPL(x86_msi_msg_get_destid);
-#ifdef CONFIG_X86_64
-void __init acpi_wake_cpu_handler_update(wakeup_cpu_handler handler)
-{
- struct apic **drv;
-
- for (drv = __apicdrivers; drv < __apicdrivers_end; drv++)
- (*drv)->wakeup_secondary_cpu_64 = handler;
-}
-#endif
-
-/*
- * Override the generic EOI implementation with an optimized version.
- * Only called during early boot when only one CPU is active and with
- * interrupts disabled, so we know this does not race with actual APIC driver
- * use.
- */
-void __init apic_set_eoi_cb(void (*eoi)(void))
-{
- struct apic **drv;
-
- for (drv = __apicdrivers; drv < __apicdrivers_end; drv++) {
- /* Should happen once for each apic */
- WARN_ON((*drv)->eoi == eoi);
- (*drv)->native_eoi = (*drv)->eoi;
- (*drv)->eoi = eoi;
- }
-}
-
static void __init apic_bsp_up_setup(void)
{
#ifdef CONFIG_X86_64
--- a/arch/x86/kernel/apic/apic_flat_64.c
+++ b/arch/x86/kernel/apic/apic_flat_64.c
@@ -143,11 +143,7 @@ static int physflat_acpi_madt_oem_check(
static int physflat_probe(void)
{
- if (apic == &apic_physflat || num_possible_cpus() > 8 ||
- jailhouse_paravirt())
- return 1;
-
- return 0;
+ return apic == &apic_physflat || num_possible_cpus() > 8 || jailhouse_paravirt();
}
static struct apic apic_physflat __ro_after_init = {
--- a/arch/x86/kernel/apic/bigsmp_32.c
+++ b/arch/x86/kernel/apic/bigsmp_32.c
@@ -119,10 +119,8 @@ bool __init apic_bigsmp_possible(bool cm
void __init apic_bigsmp_force(void)
{
- if (apic != &apic_bigsmp) {
- apic = &apic_bigsmp;
- pr_info("Overriding APIC driver with bigsmp\n");
- }
+ if (apic != &apic_bigsmp)
+ apic_install_driver(&apic_bigsmp);
}
apic_driver(apic_bigsmp);
--- /dev/null
+++ b/arch/x86/kernel/apic/init.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define pr_fmt(fmt) "APIC: " fmt
+
+#include <asm/apic.h>
+
+#include "local.h"
+
+void __init apic_install_driver(struct apic *driver)
+{
+ if (apic == driver)
+ return;
+
+ apic = driver;
+
+ if (IS_ENABLED(CONFIG_X86_X2APIC) && apic->x2apic_set_max_apicid)
+ apic->max_apic_id = x2apic_max_apicid;
+
+ pr_info("Switched APIC routing to: %s\n", driver->name);
+}
+
+#ifdef CONFIG_X86_64
+void __init acpi_wake_cpu_handler_update(wakeup_cpu_handler handler)
+{
+ struct apic **drv;
+
+ for (drv = __apicdrivers; drv < __apicdrivers_end; drv++)
+ (*drv)->wakeup_secondary_cpu_64 = handler;
+}
+#endif
+
+/*
+ * Override the generic EOI implementation with an optimized version.
+ * Only called during early boot when only one CPU is active and with
+ * interrupts disabled, so we know this does not race with actual APIC driver
+ * use.
+ */
+void __init apic_set_eoi_cb(void (*eoi)(void))
+{
+ struct apic **drv;
+
+ for (drv = __apicdrivers; drv < __apicdrivers_end; drv++) {
+ /* Should happen once for each apic */
+ WARN_ON((*drv)->eoi == eoi);
+ (*drv)->native_eoi = (*drv)->eoi;
+ (*drv)->eoi = eoi;
+ }
+}
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -82,7 +82,7 @@ static int __init parse_apic(char *arg)
for (drv = __apicdrivers; drv < __apicdrivers_end; drv++) {
if (!strcmp((*drv)->name, arg)) {
- apic = *drv;
+ apic_install_driver(*drv);
cmdline_apic = 1;
return 0;
}
@@ -129,7 +129,7 @@ void __init x86_32_probe_apic(void)
for (drv = __apicdrivers; drv < __apicdrivers_end; drv++) {
if ((*drv)->probe()) {
- apic = *drv;
+ apic_install_driver(*drv);
break;
}
}
@@ -137,5 +137,4 @@ void __init x86_32_probe_apic(void)
if (drv == __apicdrivers_end)
panic("Didn't find an APIC driver");
}
- printk(KERN_INFO "Using APIC driver %s\n", apic->name);
}
--- a/arch/x86/kernel/apic/probe_64.c
+++ b/arch/x86/kernel/apic/probe_64.c
@@ -13,19 +13,6 @@
#include "local.h"
-static __init void apic_install_driver(struct apic *driver)
-{
- if (apic == driver)
- return;
-
- apic = driver;
-
- if (IS_ENABLED(CONFIG_X86_X2APIC) && apic->x2apic_set_max_apicid)
- apic->max_apic_id = x2apic_max_apicid;
-
- pr_info("Switched APIC routing to %s:\n", apic->name);
-}
-
/* Select the appropriate APIC driver */
void __init x86_64_probe_apic(void)
{
--- a/arch/x86/xen/apic.c
+++ b/arch/x86/xen/apic.c
@@ -160,20 +160,16 @@ static struct apic xen_pv_apic = {
static void __init xen_apic_check(void)
{
- if (apic == &xen_pv_apic)
- return;
-
- pr_info("Switched APIC routing from %s to %s.\n", apic->name,
- xen_pv_apic.name);
- apic = &xen_pv_apic;
+ apic_install_driver(&xen_pv_apic);
}
+
void __init xen_init_apic(void)
{
x86_apic_ops.io_apic_read = xen_io_apic_read;
/* On PV guests the APIC CPUID bit is disabled so none of the
* routines end up executing. */
if (!xen_initial_domain())
- apic = &xen_pv_apic;
+ apic_install_driver(&xen_pv_apic);

This is working, but it produces a WARN() splat when booting as an unprivileged
Xen PV guest from static_call patching (static_call_init() hasn't been called
yet).

The diff below on top is fixing the issue:

diff --git a/arch/x86/xen/apic.c b/arch/x86/xen/apic.c
index 1838aefc632f..84f24268670b 100644
--- a/arch/x86/xen/apic.c
+++ b/arch/x86/xen/apic.c
@@ -163,14 +163,18 @@ static void __init xen_apic_check(void)
apic_install_driver(&xen_pv_apic);
}

+void __init xen_apic_install(void)
+{
+ /*
+ * On PV guests the APIC CPUID bit is disabled so none of the
+ * routines end up executing.
+ */
+ apic_install_driver(&xen_pv_apic);
+}
+
void __init xen_init_apic(void)
{
x86_apic_ops.io_apic_read = xen_io_apic_read;
- /* On PV guests the APIC CPUID bit is disabled so none of the
- * routines end up executing. */
- if (!xen_initial_domain())
- apic_install_driver(&xen_pv_apic);
-
x86_platform.apic_post_init = xen_apic_check;
}
apic_driver(xen_pv_apic);
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index c6b42c66c60c..ff2d0754ce62 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -188,6 +188,9 @@ static void __init _get_smp_config(unsigned int early)
static void __init xen_pv_smp_prepare_boot_cpu(void)
{
BUG_ON(smp_processor_id() != 0);
+
+ xen_apic_install();
+
native_smp_prepare_boot_cpu();

if (!xen_feature(XENFEAT_writable_page_tables))
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 408a2aa66c69..217e4b625e4d 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -119,6 +119,7 @@ static inline void __init xen_init_vga(const struct dom0_vga_console_info *info,
void xen_add_preferred_consoles(void);

void __init xen_init_apic(void);
+void __init xen_apic_install(void);

#ifdef CONFIG_XEN_EFI
extern void xen_efi_init(struct boot_params *boot_params);


Juergen

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