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Date:      Tue, 14 Jan 2025 14:43:39 GMT
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org
Subject:   git: f849557c06e5 - stable/14 - x86: Short-circuit ipi_all_but_self() on UP systems
Message-ID:  <202501141443.50EEhdmw014391@gitrepo.freebsd.org>

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The branch stable/14 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=f849557c06e55e7ebedc1b5c873fdf5111587918

commit f849557c06e55e7ebedc1b5c873fdf5111587918
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2025-01-07 17:58:58 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2025-01-14 14:14:42 +0000

    x86: Short-circuit ipi_all_but_self() on UP systems
    
    Apparently this is required on old intel hw, see
    https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=275086#c3
    
    PR:             275086
    Reviewed by:    mav, kib
    Fixes:          279cd05b7e4d ("Use APIC_IPI_DEST_OTHERS for bitmapped IPIs too.")
    MFC after:      1 week
    Diagnosed by:   Ben Wilber <ben@desync.com>
    Differential Revision:  https://reviews.freebsd.org/D48361
    
    (cherry picked from commit 254a2b767f9a39f1541e0a07a70bbe269e86ad70)
---
 sys/x86/x86/mp_x86.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c
index 11b11471d736..c52102e2de1e 100644
--- a/sys/x86/x86/mp_x86.c
+++ b/sys/x86/x86/mp_x86.c
@@ -1427,6 +1427,9 @@ ipi_all_but_self(u_int ipi)
 	cpuset_t other_cpus;
 	int cpu, c;
 
+	if (mp_ncpus == 1)
+		return;
+
 	/*
 	 * IPI_STOP_HARD maps to a NMI and the trap handler needs a bit
 	 * of help in order to understand what is the source.



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