From f71bb11887bae80ab718b3f38f1c1e80c07676a3 Mon Sep 17 00:00:00 2001 From: Bruce Ashfield Date: Fri, 28 Jun 2024 12:55:18 -0400 Subject: [PATCH] cpu/amd: inhibit SMP check for qemux86 When booting with kvm enabled on a AMD host, the following trace is thrown: [ 0.084519] ------------[ cut here ]------------ [ 0.084519] WARNING: This combination of AMD processors is not suitable for SMP. [ 0.084519] WARNING: CPU: 1 PID: 0 at /arch/x86/kernel/cpu/amd.c:341 init_amd+0xaee/0xbcc [ 0.084519] Modules linked in: [ 0.084519] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.6.32-yocto-standard #1 [ 0.084519] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 This warning is not valid in our configuration and is unnecesarily causing issue with debug. This has been know for some time (10+ years), but no acceptable solutioon has been found upstream: https://lists.gnu.org/archive/html/qemu-devel/2010-03/msg01428.html https://lkml.org/lkml/2010/3/30/397 We have a configuration CONFIG_QEMUX86 that has been added for situations like this. When that value is defined, we inhibit the warning, but leave it as-is for other BSPs. Signed-off-by: Bruce Ashfield --- arch/x86/kernel/cpu/amd.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 9fd91022d92d..904c4bb7e3b5 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -338,9 +338,13 @@ static void init_amd_k7(struct cpuinfo_x86 *c) * Don't taint if we are running SMP kernel on a single non-MP * approved Athlon */ - WARN_ONCE(1, "WARNING: This combination of AMD" - " processors is not suitable for SMP.\n"); - add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_NOW_UNRELIABLE); + /* disable the warning if qemux86 is configured, since the warning + is not accurate for the virtualized cpu and host combination */ + if (!IS_ENABLED(CONFIG_QEMUX86)) { + WARN_ONCE(1, "WARNING: This combination of AMD" + " processors is not suitable for SMP.\n"); + add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_NOW_UNRELIABLE); + } #endif } -- 2.39.2