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Work around regression in 4.15 in smpboot.c

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Linux commit b4c0a7326f5d breaks PV domains since native_smp_cpus_done()
isn't called in that case. So __max_logical_packages is uninitialized
and breaks for example coretemp.
This commit is contained in:
Simon Gaiser 2018-02-07 18:40:35 +01:00
parent d922e28b0b
commit 5468bc3f11
3 changed files with 141 additions and 0 deletions
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36
patches.xen/Revert-x86-smpboot-Do-not-use-smp_num_siblings-in-__.patch Normal file
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@ -0,0 +1,36 @@
From 09c7513ec86caec1a1c304cf34d512011712f5c4 Mon Sep 17 00:00:00 2001
From: Simon Gaiser <simon@invisiblethingslab.com>
Date: Wed, 7 Feb 2018 18:30:53 +0100
Subject: [PATCH 1/2] Revert "x86/smpboot: Do not use smp_num_siblings in
__max_logical_packages calculation"
This reverts commit 947134d9b00f342415af7eddd42a5fce7262a1b9.
---
arch/x86/kernel/smpboot.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index ed556d50d7ed..3dd6a6a5ffbc 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -106,7 +106,7 @@ EXPORT_SYMBOL(__max_logical_packages);
static unsigned int logical_packages __read_mostly;
/* Maximum number of SMT threads on any online core */
-int __read_mostly __max_smt_threads = 1;
+int __max_smt_threads __read_mostly;
/* Flag to indicate if a complete sched domain rebuild is required */
bool x86_topology_update;
@@ -1291,7 +1291,7 @@ void __init native_smp_cpus_done(unsigned int max_cpus)
* Today neither Intel nor AMD support heterogenous systems so
* extrapolate the boot cpu's data to all packages.
*/
- ncpus = cpu_data(0).booted_cores * topology_max_smt_threads();
+ ncpus = cpu_data(0).booted_cores * smp_num_siblings;
__max_logical_packages = DIV_ROUND_UP(nr_cpu_ids, ncpus);
pr_info("Max logical packages: %u\n", __max_logical_packages);
--
2.15.1

101
patches.xen/Revert-x86-smpboot-Fix-__max_logical_packages-estima.patch Normal file
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@ -0,0 +1,101 @@
From 3379207879b4f1b6dff0cca0a713d5309e045c12 Mon Sep 17 00:00:00 2001
From: Simon Gaiser <simon@invisiblethingslab.com>
Date: Wed, 7 Feb 2018 18:31:03 +0100
Subject: [PATCH 2/2] Revert "x86/smpboot: Fix __max_logical_packages estimate"
This reverts commit b4c0a7326f5dc0ef7a64128b0ae7d081f4b2cbd1.
---
arch/x86/kernel/smpboot.c | 55 ++++++++++++++++++++++++++++++++++++++---------
1 file changed, 45 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 3dd6a6a5ffbc..72b3eb321b49 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -301,6 +301,12 @@ int topology_update_package_map(unsigned int pkg, unsigned int cpu)
if (new >= 0)
goto found;
+ if (logical_packages >= __max_logical_packages) {
+ pr_warn("Package %u of CPU %u exceeds BIOS package data %u.\n",
+ logical_packages, cpu, __max_logical_packages);
+ return -ENOSPC;
+ }
+
new = logical_packages++;
if (new != pkg) {
pr_info("CPU %u Converting physical %u to logical package %u\n",
@@ -311,6 +317,44 @@ int topology_update_package_map(unsigned int pkg, unsigned int cpu)
return 0;
}
+static void __init smp_init_package_map(struct cpuinfo_x86 *c, unsigned int cpu)
+{
+ unsigned int ncpus;
+
+ /*
+ * Today neither Intel nor AMD support heterogenous systems. That
+ * might change in the future....
+ *
+ * While ideally we'd want '* smp_num_siblings' in the below @ncpus
+ * computation, this won't actually work since some Intel BIOSes
+ * report inconsistent HT data when they disable HT.
+ *
+ * In particular, they reduce the APIC-IDs to only include the cores,
+ * but leave the CPUID topology to say there are (2) siblings.
+ * This means we don't know how many threads there will be until
+ * after the APIC enumeration.
+ *
+ * By not including this we'll sometimes over-estimate the number of
+ * logical packages by the amount of !present siblings, but this is
+ * still better than MAX_LOCAL_APIC.
+ *
+ * We use total_cpus not nr_cpu_ids because nr_cpu_ids can be limited
+ * on the command line leading to a similar issue as the HT disable
+ * problem because the hyperthreads are usually enumerated after the
+ * primary cores.
+ */
+ ncpus = boot_cpu_data.x86_max_cores;
+ if (!ncpus) {
+ pr_warn("x86_max_cores == zero !?!?");
+ ncpus = 1;
+ }
+
+ __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus);
+ pr_info("Max logical packages: %u\n", __max_logical_packages);
+
+ topology_update_package_map(c->phys_proc_id, cpu);
+}
+
void __init smp_store_boot_cpu_info(void)
{
int id = 0; /* CPU 0 */
@@ -318,7 +362,7 @@ void __init smp_store_boot_cpu_info(void)
*c = boot_cpu_data;
c->cpu_index = id;
- topology_update_package_map(c->phys_proc_id, id);
+ smp_init_package_map(c, id);
c->initialized = true;
}
@@ -1284,16 +1328,7 @@ void __init native_smp_prepare_boot_cpu(void)
void __init native_smp_cpus_done(unsigned int max_cpus)
{
- int ncpus;
-
pr_debug("Boot done\n");
- /*
- * Today neither Intel nor AMD support heterogenous systems so
- * extrapolate the boot cpu's data to all packages.
- */
- ncpus = cpu_data(0).booted_cores * smp_num_siblings;
- __max_logical_packages = DIV_ROUND_UP(nr_cpu_ids, ncpus);
- pr_info("Max logical packages: %u\n", __max_logical_packages);
if (x86_has_numa_in_package)
set_sched_topology(x86_numa_in_package_topology);
--
2.15.1

4
series.conf
View File

@ -37,6 +37,10 @@ patches.xen/Revert-xen-optimize-xenbus-driver-for-multiple-concu.patch
# Upstream patch for 4.15
patches.xen/x86-xen-init-gs-very-early-to-avoid-page-faults-with.patch
# Workaround for regression in 4.15 in smpboot.c
patches.xen/Revert-x86-smpboot-Do-not-use-smp_num_siblings-in-__.patch
patches.xen/Revert-x86-smpboot-Fix-__max_logical_packages-estima.patch
# Hardware-specific fixes, backported from newer kernel and/or developers branches
patches.backports/v2-2-2-Input-synaptics---Lenovo-X1-Carbon-5-should-use-SMBUS-RMI.patch
patches.backports/Input-synaptics---add-Intertouch-support-on-X1-Carbon-6th-and-X280.patch