Messages in this thread Patch in this message | | | Date | Sat, 19 Mar 2016 16:56:51 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 2/3] x86/topology: Fix AMD core count |
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On Sat, Mar 19, 2016 at 10:24:59AM +0100, Thomas Gleixner wrote: > On Fri, 18 Mar 2016, Peter Zijlstra wrote: > > It turns out AMD gets x86_max_cores wrong when there are compute > > units. > > > > The issue is that Linux assumes: > > > > nr_logical_cpus = nr_cores * nr_siblings > > > > But AMD reports its CU unit as 2 cores, but then sets num_smp_siblings > > to 2 as well. > > > > Cc: Ingo Molnar <mingo@kernel.org> > > Cc: Borislav Petkov <bp@alien8.de> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Andreas Herrmann <aherrmann@suse.com> > > Reported-by: Xiong Zhou <jencce.kernel@gmail.com> > > Fixes: 1f12e32f4cd5 ("x86/topology: Create logical package id") > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > Link: http://lkml.kernel.org/r/20160317095220.GO6344@twins.programming.kicks-ass.net > > --- > > arch/x86/kernel/cpu/amd.c | 8 ++++---- > > arch/x86/kernel/smpboot.c | 11 ++++++----- > > 2 files changed, 10 insertions(+), 9 deletions(-) > > > > --- a/arch/x86/kernel/cpu/amd.c > > +++ b/arch/x86/kernel/cpu/amd.c > > @@ -313,9 +313,9 @@ static void amd_get_topology(struct cpui > > node_id = ecx & 7; > > > > /* get compute unit information */ > > - smp_num_siblings = ((ebx >> 8) & 3) + 1; > > + cores_per_cu = smp_num_siblings = ((ebx >> 8) & 3) + 1; > > + c->x86_max_cores /= smp_num_siblings; > > Unfortunately that will break stuff in event/amd/core.c, ras/mce_amd_inj.c > which rely on the AMD interpretation of c->x86_max_cores.
What is the events/amd/core.c check even mean? We alloc an amd_nb per core but not per thread?
The mce_amd_inj.c thing we could fix probably like this:
--- diff --git a/arch/x86/ras/mce_amd_inj.c b/arch/x86/ras/mce_amd_inj.c index 55d38cfa46c2..b5a917d943c8 100644 --- a/arch/x86/ras/mce_amd_inj.c +++ b/arch/x86/ras/mce_amd_inj.c @@ -203,12 +203,7 @@ static void trigger_thr_int(void *info) static u32 get_nbc_for_node(int node_id) { - struct cpuinfo_x86 *c = &boot_cpu_data; - u32 cores_per_node; - - cores_per_node = c->x86_max_cores / amd_get_nodes_per_socket(); - - return cores_per_node * node_id; + return boot_cpu_data.x86_max_cores * node_id; } static void toggle_nb_mca_mst_cpu(u16 nid) --- -- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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