diff options
Diffstat (limited to '0024-x86-smp-do-not-use-shorthand-IPI-destinations-in-CPU.patch')
| -rw-r--r-- | 0024-x86-smp-do-not-use-shorthand-IPI-destinations-in-CPU.patch | 98 |
1 files changed, 0 insertions, 98 deletions
diff --git a/0024-x86-smp-do-not-use-shorthand-IPI-destinations-in-CPU.patch b/0024-x86-smp-do-not-use-shorthand-IPI-destinations-in-CPU.patch deleted file mode 100644 index b69c88c..0000000 --- a/0024-x86-smp-do-not-use-shorthand-IPI-destinations-in-CPU.patch +++ /dev/null @@ -1,98 +0,0 @@ -From 98238d49ecb149a5ac07cb8032817904c404ac2b Mon Sep 17 00:00:00 2001 -From: =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.com> -Date: Wed, 26 Jun 2024 13:38:36 +0200 -Subject: [PATCH 24/56] x86/smp: do not use shorthand IPI destinations in CPU - hot{,un}plug contexts -MIME-Version: 1.0 -Content-Type: text/plain; charset=UTF-8 -Content-Transfer-Encoding: 8bit - -Due to the current rwlock logic, if the CPU calling get_cpu_maps() does -so from a cpu_hotplug_{begin,done}() region the function will still -return success, because a CPU taking the rwlock in read mode after -having taken it in write mode is allowed. Such corner case makes using -get_cpu_maps() alone not enough to prevent using the shorthand in CPU -hotplug regions. - -Introduce a new helper to detect whether the current caller is between a -cpu_hotplug_{begin,done}() region and use it in send_IPI_mask() to restrict -shorthand usage. - -Fixes: 5500d265a2a8 ('x86/smp: use APIC ALLBUT destination shorthand when possible') -Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> -Reviewed-by: Jan Beulich <jbeulich@suse.com> -master commit: 171c52fba5d94e050d704770480dcb983490d0ad -master date: 2024-06-12 14:29:31 +0200 ---- - xen/arch/x86/smp.c | 2 +- - xen/common/cpu.c | 5 +++++ - xen/include/xen/cpu.h | 10 ++++++++++ - xen/include/xen/rwlock.h | 2 ++ - 4 files changed, 18 insertions(+), 1 deletion(-) - -diff --git a/xen/arch/x86/smp.c b/xen/arch/x86/smp.c -index 3a331cbdbc..340fcafb46 100644 ---- a/xen/arch/x86/smp.c -+++ b/xen/arch/x86/smp.c -@@ -88,7 +88,7 @@ void send_IPI_mask(const cpumask_t *mask, int vector) - * the system have been accounted for. - */ - if ( system_state > SYS_STATE_smp_boot && -- !unaccounted_cpus && !disabled_cpus && -+ !unaccounted_cpus && !disabled_cpus && !cpu_in_hotplug_context() && - /* NB: get_cpu_maps lock requires enabled interrupts. */ - local_irq_is_enabled() && (cpus_locked = get_cpu_maps()) && - (park_offline_cpus || -diff --git a/xen/common/cpu.c b/xen/common/cpu.c -index 8709db4d29..6e35b114c0 100644 ---- a/xen/common/cpu.c -+++ b/xen/common/cpu.c -@@ -68,6 +68,11 @@ void cpu_hotplug_done(void) - write_unlock(&cpu_add_remove_lock); - } - -+bool cpu_in_hotplug_context(void) -+{ -+ return rw_is_write_locked_by_me(&cpu_add_remove_lock); -+} -+ - static NOTIFIER_HEAD(cpu_chain); - - void __init register_cpu_notifier(struct notifier_block *nb) -diff --git a/xen/include/xen/cpu.h b/xen/include/xen/cpu.h -index e1d4eb5967..6bf5786750 100644 ---- a/xen/include/xen/cpu.h -+++ b/xen/include/xen/cpu.h -@@ -13,6 +13,16 @@ void put_cpu_maps(void); - void cpu_hotplug_begin(void); - void cpu_hotplug_done(void); - -+/* -+ * Returns true when the caller CPU is between a cpu_hotplug_{begin,done}() -+ * region. -+ * -+ * This is required to safely identify hotplug contexts, as get_cpu_maps() -+ * would otherwise succeed because a caller holding the lock in write mode is -+ * allowed to acquire the same lock in read mode. -+ */ -+bool cpu_in_hotplug_context(void); -+ - /* Receive notification of CPU hotplug events. */ - void register_cpu_notifier(struct notifier_block *nb); - -diff --git a/xen/include/xen/rwlock.h b/xen/include/xen/rwlock.h -index 9e35ee2edf..dc74d1c057 100644 ---- a/xen/include/xen/rwlock.h -+++ b/xen/include/xen/rwlock.h -@@ -309,6 +309,8 @@ static always_inline void write_lock_irq(rwlock_t *l) - - #define rw_is_locked(l) _rw_is_locked(l) - #define rw_is_write_locked(l) _rw_is_write_locked(l) -+#define rw_is_write_locked_by_me(l) \ -+ lock_evaluate_nospec(_is_write_locked_by_me(atomic_read(&(l)->cnts))) - - - typedef struct percpu_rwlock percpu_rwlock_t; --- -2.45.2 - |