[RFC PATCH 6/9] x86/apic: Introduce Remote Action Request Operations

Rik van Riel
2025-05-06T00:48:23Z

From: Rik van Riel <riel@fb.com>

RAR TLB flushing is started by sending a command to the APIC.
This patch adds Remote Action Request commands.

[riel: move some things around to acount for 6 years of changes]

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Rik van Riel <riel@surriel.com>
---
arch/x86/include/asm/apicdef.h | 1 +
arch/x86/include/asm/irq_vectors.h | 5 +++++
arch/x86/include/asm/smp.h | 15 +++++++++++++++
arch/x86/kernel/apic/ipi.c | 23 +++++++++++++++++++----
arch/x86/kernel/apic/local.h | 3 +++
arch/x86/kernel/smp.c | 3 +++
6 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/apicdef.h b/arch/x86/include/asm/apicdef.h
index 094106b6a538..b152d45af91a 100644
--- a/arch/x86/include/asm/apicdef.h
+++ b/arch/x86/include/asm/apicdef.h
@@ -92,6 +92,7 @@
#define APIC_DM_LOWEST 0x00100
#define APIC_DM_SMI 0x00200
#define APIC_DM_REMRD 0x00300
+#define APIC_DM_RAR 0x00300
#define APIC_DM_NMI 0x00400
#define APIC_DM_INIT 0x00500
#define APIC_DM_STARTUP 0x00600
diff --git a/arch/x86/include/asm/irq_vectors.h b/arch/x86/include/asm/irq_vectors.h
index 47051871b436..c417b0015304 100644
--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -103,6 +103,11 @@
*/
#define POSTED_MSI_NOTIFICATION_VECTOR 0xeb

+/*
+ * RAR (remote action request) TLB flush
+ */
+#define RAR_VECTOR 0xe0
+
#define NR_VECTORS 256

#ifdef CONFIG_X86_LOCAL_APIC
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 0c1c68039d6f..1ab9f5fcac8a 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -40,6 +40,9 @@ struct smp_ops {

void (*send_call_func_ipi)(const struct cpumask *mask);
void (*send_call_func_single_ipi)(int cpu);
+
+ void (*send_rar_ipi)(const struct cpumask *mask);
+ void (*send_rar_single_ipi)(int cpu);
};

/* Globals due to paravirt */
@@ -100,6 +103,16 @@ static inline void arch_send_call_function_ipi_mask(const struct cpumask *mask)
smp_ops.send_call_func_ipi(mask);
}

+static inline void arch_send_rar_single_ipi(int cpu)
+{
+ smp_ops.send_rar_single_ipi(cpu);
+}
+
+static inline void arch_send_rar_ipi_mask(const struct cpumask *mask)
+{
+ smp_ops.send_rar_ipi(mask);
+}
+
void cpu_disable_common(void);
void native_smp_prepare_boot_cpu(void);
void smp_prepare_cpus_common(void);
@@ -120,6 +133,8 @@ void __noreturn mwait_play_dead(unsigned int eax_hint);
void native_smp_send_reschedule(int cpu);
void native_send_call_func_ipi(const struct cpumask *mask);
void native_send_call_func_single_ipi(int cpu);
+void native_send_rar_ipi(const struct cpumask *mask);
+void native_send_rar_single_ipi(int cpu);

asmlinkage __visible void smp_reboot_interrupt(void);
__visible void smp_reschedule_interrupt(struct pt_regs *regs);
diff --git a/arch/x86/kernel/apic/ipi.c b/arch/x86/kernel/apic/ipi.c
index 98a57cb4aa86..e5e9fc08f86c 100644
--- a/arch/x86/kernel/apic/ipi.c
+++ b/arch/x86/kernel/apic/ipi.c
@@ -79,7 +79,7 @@ void native_send_call_func_single_ipi(int cpu)
__apic_send_IPI(cpu, CALL_FUNCTION_SINGLE_VECTOR);
}

-void native_send_call_func_ipi(const struct cpumask *mask)
+static void do_native_send_ipi(const struct cpumask *mask, int vector)
{
if (static_branch_likely(&apic_use_ipi_shorthand)) {
unsigned int cpu = smp_processor_id();
@@ -88,14 +88,19 @@ void native_send_call_func_ipi(const struct cpumask *mask)
goto sendmask;

if (cpumask_test_cpu(cpu, mask))
- __apic_send_IPI_all(CALL_FUNCTION_VECTOR);
+ __apic_send_IPI_all(vector);
else if (num_online_cpus() > 1)
- __apic_send_IPI_allbutself(CALL_FUNCTION_VECTOR);
+ __apic_send_IPI_allbutself(vector);
return;
}

sendmask:
- __apic_send_IPI_mask(mask, CALL_FUNCTION_VECTOR);
+ __apic_send_IPI_mask(mask, vector);
+}
+
+void native_send_call_func_ipi(const struct cpumask *mask)
+{
+ do_native_send_ipi(mask, CALL_FUNCTION_VECTOR);
}

void apic_send_nmi_to_offline_cpu(unsigned int cpu)
@@ -106,6 +111,16 @@ void apic_send_nmi_to_offline_cpu(unsigned int cpu)
return;
apic->send_IPI(cpu, NMI_VECTOR);
}
+
+void native_send_rar_single_ipi(int cpu)
+{
+ apic->send_IPI_mask(cpumask_of(cpu), RAR_VECTOR);
+}
+
+void native_send_rar_ipi(const struct cpumask *mask)
+{
+ do_native_send_ipi(mask, RAR_VECTOR);
+}
#endif /* CONFIG_SMP */

static inline int __prepare_ICR2(unsigned int mask)
diff --git a/arch/x86/kernel/apic/local.h b/arch/x86/kernel/apic/local.h
index bdcf609eb283..833669174267 100644
--- a/arch/x86/kernel/apic/local.h
+++ b/arch/x86/kernel/apic/local.h
@@ -38,6 +38,9 @@ static inline unsigned int __prepare_ICR(unsigned int shortcut, int vector,
case NMI_VECTOR:
icr |= APIC_DM_NMI;
break;
+ case RAR_VECTOR:
+ icr |= APIC_DM_RAR;
+ break;
}
return icr;
}
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 18266cc3d98c..2c51ed6aaf03 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -297,5 +297,8 @@ struct smp_ops smp_ops = {

.send_call_func_ipi = native_send_call_func_ipi,
.send_call_func_single_ipi = native_send_call_func_single_ipi,
+
+ .send_rar_ipi = native_send_rar_ipi,
+ .send_rar_single_ipi = native_send_rar_single_ipi,
};
EXPORT_SYMBOL_GPL(smp_ops);
--
2.49.0