[PATCH] x86/xen: call xen_set_upcall_vector() only after local apic setup
From: Juergen Gross <jgross@suse.com>
Date: 2022-11-12 13:23:46
Also in:
lkml, xen-devel
Subsystem:
arm port, cpu hotplug, the rest, x86 architecture (32-bit and 64-bit), xen hypervisor arm, xen hypervisor interface, xen hypervisor x86 · Maintainers:
Russell King, Thomas Gleixner, Peter Zijlstra, Linus Torvalds, Ingo Molnar, Borislav Petkov, Dave Hansen, Stefano Stabellini, Juergen Gross
Calling xen_set_upcall_vector() before the local APIC has been
initialized results in warnings when setting up the local APIC:
[ 0.037322] APIC: Stale IRR: 00080000, ...
Avoid this problem by moving the call of xen_set_upcall_vector() for
APs from xen_cpu_up_prepare_hvm() to a new hotplug callback called on
the AP before interrupts are enabled and after the local APIC has been
initialized. There is already a Xen specific hotplug state defined at
a matching position, but right now it is specific to Arm. So rename
the CPUHP_AP_ARM_XEN_STARTING to CPUHP_AP_XEN_STARTING and use it for
x86, too.
On the boot processor use the x86_init.irqs.intr_mode_init hook to
call xen_set_upcall_vector() only after the local APIC initialization.
As interrupts are on already at the time when the hook is being used,
modify xen_init_setup_upcall_vector() to disable interrupts. This is
needed as the xen_percpu_upcall flag is set only after the callback
has been registered, and the flag is needed for correctly acknowledging
an interrupt.
Fixes: b1c3497e604d ("x86/xen: Add support for HVMOP_set_evtchn_upcall_vector")
Reported-by: Jan Beulich <redacted>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
arch/arm/xen/enlighten.c | 4 ++--
arch/x86/xen/enlighten_hvm.c | 9 ---------
drivers/xen/events/events_base.c | 22 +++++++++++++++++-----
include/linux/cpuhotplug.h | 2 +-
4 files changed, 20 insertions(+), 17 deletions(-)
diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 93c8ccbf2982..1778a7a7c3ed 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c@@ -529,8 +529,8 @@ static int __init xen_guest_init(void) if (xen_initial_domain()) pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier); - return cpuhp_setup_state(CPUHP_AP_ARM_XEN_STARTING, - "arm/xen:starting", xen_starting_cpu, + return cpuhp_setup_state(CPUHP_AP_XEN_STARTING, + "xen:starting", xen_starting_cpu, xen_dying_cpu); } early_initcall(xen_guest_init);
diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index c1cd28e915a3..55d140cc6128 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c@@ -177,15 +177,6 @@ static int xen_cpu_up_prepare_hvm(unsigned int cpu) if (!xen_have_vector_callback) return 0; - if (xen_percpu_upcall) { - rc = xen_set_upcall_vector(cpu); - if (rc) { - WARN(1, "HVMOP_set_evtchn_upcall_vector" - " for CPU %d failed: %d\n", cpu, rc); - return rc; - } - } - if (xen_feature(XENFEAT_hvm_safe_pvclock)) xen_setup_timer(cpu);
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index c443f04aaad7..7609fedb2a33 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c@@ -39,6 +39,7 @@ #include <linux/ktime.h> #ifdef CONFIG_X86 +#include <asm/apic.h> #include <asm/desc.h> #include <asm/ptrace.h> #include <asm/idtentry.h>
@@ -2209,16 +2210,27 @@ void xen_setup_callback_vector(void) */ static __init void xen_init_setup_upcall_vector(void) { + unsigned long flags; + + apic_intr_mode_init(); + if (!xen_have_vector_callback) return; + local_irq_save(flags); + if ((cpuid_eax(xen_cpuid_base() + 4) & XEN_HVM_CPUID_UPCALL_VECTOR) && - !xen_set_upcall_vector(0)) + !xen_set_upcall_vector(0)) { xen_percpu_upcall = true; + WARN_ON(cpuhp_setup_state(CPUHP_AP_XEN_STARTING, "xen:starting", + xen_set_upcall_vector, NULL)); + } else if (xen_feature(XENFEAT_hvm_callback_vector)) xen_setup_callback_vector(); else xen_have_vector_callback = false; + + local_irq_restore(flags); } int xen_set_upcall_vector(unsigned int cpu)
@@ -2250,9 +2262,7 @@ static __init void xen_alloc_callback_vector(void) } #else void xen_setup_callback_vector(void) {} -static inline void xen_init_setup_upcall_vector(void) {} int xen_set_upcall_vector(unsigned int cpu) {} -static inline void xen_alloc_callback_vector(void) {} #endif /* CONFIG_XEN_PVHVM */ #endif /* CONFIG_X86 */
@@ -2314,9 +2324,11 @@ void __init xen_init_IRQ(void) if (xen_initial_domain()) pci_xen_initial_domain(); } - xen_init_setup_upcall_vector(); - xen_alloc_callback_vector(); +#ifdef CONFIG_XEN_PVHVM + x86_init.irqs.intr_mode_init = xen_init_setup_upcall_vector; + xen_alloc_callback_vector(); +#endif if (xen_hvm_domain()) { native_init_IRQ();
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f61447913db9..c232ada4e4ca 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h@@ -191,7 +191,7 @@ enum cpuhp_state { CPUHP_AP_KVM_ARM_TIMER_STARTING, /* Must be the last timer callback */ CPUHP_AP_DUMMY_TIMER_STARTING, - CPUHP_AP_ARM_XEN_STARTING, + CPUHP_AP_XEN_STARTING, CPUHP_AP_ARM_CORESIGHT_STARTING, CPUHP_AP_ARM_CORESIGHT_CTI_STARTING, CPUHP_AP_ARM64_ISNDEP_STARTING,
--
2.35.3
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