From 7621880de0bb40bae6436a5b106babc0e4718f4d Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 10 Dec 2021 10:26:52 +0100 Subject: [PATCH] x86: avoid wrong use of all-but-self IPI shorthand With "nosmp" I did observe a flood of "APIC error on CPU0: 04(04), Send accept error" log messages on an AMD system. And rightly so - nothing excludes the use of the shorthand in send_IPI_mask() in this case. Set "unaccounted_cpus" to "true" also when command line restrictions are the cause. Note that PV-shim mode is unaffected by this change, first and foremost because "nosmp" and "maxcpus=" are ignored in this case. Fixes: 5500d265a2a8 ("x86/smp: use APIC ALLBUT destination shorthand when possible") Signed-off-by: Jan Beulich Acked-by: Andrew Cooper --- xen/arch/x86/mpparse.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/mpparse.c b/xen/arch/x86/mpparse.c index 42b5ac7871..8faac289ea 100644 --- a/xen/arch/x86/mpparse.c +++ b/xen/arch/x86/mpparse.c @@ -84,9 +84,14 @@ void __init set_nr_cpu_ids(unsigned int max_cpus) if (!park_offline_cpus) tot_cpus = max_cpus; nr_cpu_ids = min(tot_cpus, NR_CPUS + 0u); - if (park_offline_cpus && nr_cpu_ids < num_processors) - printk(XENLOG_WARNING "SMP: Cannot bring up %u further CPUs\n", - num_processors - nr_cpu_ids); + if (nr_cpu_ids < num_processors) + { + unaccounted_cpus = true; + if (park_offline_cpus) + printk(XENLOG_WARNING + "SMP: Cannot bring up %u further CPUs\n", + num_processors - nr_cpu_ids); + } #ifndef nr_cpumask_bits nr_cpumask_bits = ROUNDUP(nr_cpu_ids, BITS_PER_LONG); -- 2.30.2