[PATCH 0/3 v4] Fix panic in logical packages calculation

[PATCH 0/3 v4] Fix panic in logical packages calculation

[Prarit Bhargava]

A system booted with a small number of cores enabled per package
panics because the estimate of __max_logical_packages is too low.
This occurs when the total number of active cores across all packages
is less than the maximum core count for a single package.

Andi noted that the logical_packages calculation wastes 128k on 64-bit
x86 systems and posted patches to fix the allocation.  His patches
result in significant memory size savings, and I have put my
fix on top of those patches.

Here's an example of the panic:

     smpboot: Booting Node   1, Processors  #1 OK
     smpboot: Package 1 of CPU 1 exceeds BIOS package data 1.
     ------------[ cut here ]------------
     kernel BUG at arch/x86/kernel/cpu/common.c:1087!
     invalid opcode: 0000 [#1] SMP
     Modules linked in:
     CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.0-rc2+ #4

This was tested by dropping the number of active cores across
all packages to reproduce the bug above.  Additional testing included
2 socket and 4 socket systems and hotplugging entire sockets in different
order.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Piotr Luc <piotr.luc@intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>

Andi Kleen (2):
  perf/x86/intel/uncore: Cache logical pkg id in uncore driver
  x86/topology: Avoid wasting 128k for package id array

Prarit Bhargava (1):
  x86/smpboot: Fix __max_logical_packages estimate

 arch/x86/events/intel/uncore.c       |   1 +
 arch/x86/events/intel/uncore.h       |   1 +
 arch/x86/events/intel/uncore_snbep.c |   2 +-
 arch/x86/include/asm/processor.h     |   4 +-
 arch/x86/kernel/smpboot.c            | 137 ++++++++++++-----------------------
 5 files changed, 53 insertions(+), 92 deletions(-)

-- 
2.15.0.rc0.39.g2f0e14e64

[PATCH 1/3 v4] perf/x86/intel/uncore: Cache logical pkg id in uncore driver

[Prarit Bhargava]

From: Andi Kleen <ak@linux.intel.com>

The SNB-EP uncore driver is the only user of topology_phys_to_logical_pkg
in a performance critical path. Change it query the logical pkg ID
only once at initialization time and then cache it in box structure.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Piotr Luc <piotr.luc@intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/events/intel/uncore.c       | 1 +
 arch/x86/events/intel/uncore.h       | 1 +
 arch/x86/events/intel/uncore_snbep.c | 2 +-
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
index d45e06346f14..87ef77982248 100644
--- a/arch/x86/events/intel/uncore.c
+++ b/arch/x86/events/intel/uncore.c
@@ -947,6 +947,7 @@ static int uncore_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id
 
 	atomic_inc(&box->refcnt);
 	box->pci_phys_id = phys_id;
+	box->logical_pkg_id = topology_phys_to_logical_pkg(box->pci_phys_id);
 	box->pkgid = pkg;
 	box->pci_dev = pdev;
 	box->pmu = pmu;
diff --git a/arch/x86/events/intel/uncore.h b/arch/x86/events/intel/uncore.h
index df5989f27b1b..6214cd33a9fb 100644
--- a/arch/x86/events/intel/uncore.h
+++ b/arch/x86/events/intel/uncore.h
@@ -99,6 +99,7 @@ struct intel_uncore_extra_reg {
 
 struct intel_uncore_box {
 	int pci_phys_id;
+	int logical_pkg_id;
 	int pkgid;
 	int n_active;	/* number of active events */
 	int n_events;
diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index a7196818416a..252d371b488b 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -1056,7 +1056,7 @@ static void snbep_qpi_enable_event(struct intel_uncore_box *box, struct perf_eve
 
 	if (reg1->idx != EXTRA_REG_NONE) {
 		int idx = box->pmu->pmu_idx + SNBEP_PCI_QPI_PORT0_FILTER;
-		int pkg = topology_phys_to_logical_pkg(box->pci_phys_id);
+		int pkg = box->logical_pkg_id;
 		struct pci_dev *filter_pdev = uncore_extra_pci_dev[pkg].dev[idx];
 
 		if (filter_pdev) {
-- 
2.15.0.rc0.39.g2f0e14e64

[PATCH 2/3 v4] x86/topology: Avoid wasting 128k for package id array

[Prarit Bhargava]

From: Andi Kleen <ak@linux.intel.com>

I was looking at large early boot allocations and noticed that since
(1f12e32f x86/topology: Create logical package id) every 64bit system
allocates a 128k array to convert logical package ids.

This happens because the array is sized to (MAX_LOCAL_APIC * u16) = 128k.
This is a lot of waste especially for most systems which have one or two
sockets.

Use a dynamically allocated array of size logical_packages to map
the logical and physical packages.

[v2]: Decrease logical_packages when the last thread in a socket is
removed.
[v3]: Add more logic to keep logical and physical package IDs
in synch.
[v4]: Keep logical mapping static by using hybrid approach of a small logical
to physical array and keeping logical cpu information in cpu_data.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Piotr Luc <piotr.luc@intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/include/asm/processor.h |  4 +-
 arch/x86/kernel/smpboot.c        | 86 +++++++++++++++++++---------------------
 2 files changed, 43 insertions(+), 47 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index b390ff76e58f..f4ab1edf4e24 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -124,8 +124,10 @@ struct cpuinfo_x86 {
 	u16			booted_cores;
 	/* Physical processor id: */
 	u16			phys_proc_id;
-	/* Logical processor id: */
+	/* Logical processor (package) id: */
 	u16			logical_proc_id;
+	/* Physical package ID */
+	u16			phys_pkg_id;
 	/* Core id: */
 	u16			cpu_core_id;
 	/* Index into per_cpu list: */
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index ad59edd84de7..ca615bc94e82 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -99,12 +99,10 @@ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
 DEFINE_PER_CPU_READ_MOSTLY(struct cpuinfo_x86, cpu_info);
 EXPORT_PER_CPU_SYMBOL(cpu_info);
 
-/* Logical package management. We might want to allocate that dynamically */
-static int *physical_to_logical_pkg __read_mostly;
-static unsigned long *physical_package_map __read_mostly;;
-static unsigned int max_physical_pkg_id __read_mostly;
+/* Logical package management.*/
 unsigned int __max_logical_packages __read_mostly;
 EXPORT_SYMBOL(__max_logical_packages);
+static u16 *logical_to_physical_pkg_map;
 static unsigned int logical_packages __read_mostly;
 
 /* Maximum number of SMT threads on any online core */
@@ -278,6 +276,23 @@ static void notrace start_secondary(void *unused)
 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 }
 
+/**
+ * topology_phys_to_logical_pkg - Map a physical package id to a logical
+ *
+ * Returns logical package id or -1 if not found
+ */
+int topology_phys_to_logical_pkg(unsigned int phys_pkg)
+{
+	int log_pkg;
+
+	for (log_pkg = 0; log_pkg < logical_packages; log_pkg++)
+		if (logical_to_physical_pkg_map[log_pkg] == phys_pkg)
+			return log_pkg;
+
+	return -1;
+}
+EXPORT_SYMBOL(topology_phys_to_logical_pkg);
+
 /**
  * topology_update_package_map - Update the physical to logical package map
  * @pkg:	The physical package id as retrieved via CPUID
@@ -285,17 +300,11 @@ static void notrace start_secondary(void *unused)
  */
 int topology_update_package_map(unsigned int pkg, unsigned int cpu)
 {
-	unsigned int new;
-
-	/* Called from early boot ? */
-	if (!physical_package_map)
-		return 0;
-
-	if (pkg >= max_physical_pkg_id)
-		return -EINVAL;
+	int new;
+	u16 *ltp_pkg_map_new;
 
-	/* Set the logical package id */
-	if (test_and_set_bit(pkg, physical_package_map))
+	new = topology_phys_to_logical_pkg(pkg);
+	if (new >= 0)
 		goto found;
 
 	if (logical_packages >= __max_logical_packages) {
@@ -305,34 +314,30 @@ int topology_update_package_map(unsigned int pkg, unsigned int cpu)
 	}
 
 	new = logical_packages++;
-	if (new != pkg) {
-		pr_info("CPU %u Converting physical %u to logical package %u\n",
-			cpu, pkg, new);
+
+	/* Allocate and copy a new array */
+	ltp_pkg_map_new = kmalloc(logical_packages * sizeof(u16), GFP_KERNEL);
+	BUG_ON(!ltp_pkg_map_new);
+	if (logical_to_physical_pkg_map) {
+		memcpy(ltp_pkg_map_new, logical_to_physical_pkg_map,
+		       logical_packages * sizeof(u16));
+		kfree(logical_to_physical_pkg_map);
 	}
-	physical_to_logical_pkg[pkg] = new;
+	logical_to_physical_pkg_map = ltp_pkg_map_new;
+	logical_to_physical_pkg_map[new] = pkg;
 
+	if (pkg != new)
+		pr_info("CPU %u Converting physical %u to logical package %u\n",
+			cpu, pkg, new);
 found:
-	cpu_data(cpu).logical_proc_id = physical_to_logical_pkg[pkg];
+	cpu_data(cpu).phys_pkg_id = pkg;
+	cpu_data(cpu).logical_proc_id = new;
 	return 0;
 }
 
-/**
- * topology_phys_to_logical_pkg - Map a physical package id to a logical
- *
- * Returns logical package id or -1 if not found
- */
-int topology_phys_to_logical_pkg(unsigned int phys_pkg)
-{
-	if (phys_pkg >= max_physical_pkg_id)
-		return -1;
-	return physical_to_logical_pkg[phys_pkg];
-}
-EXPORT_SYMBOL(topology_phys_to_logical_pkg);
-
 static void __init smp_init_package_map(struct cpuinfo_x86 *c, unsigned int cpu)
 {
 	unsigned int ncpus;
-	size_t size;
 
 	/*
 	 * Today neither Intel nor AMD support heterogenous systems. That
@@ -363,21 +368,10 @@ static void __init smp_init_package_map(struct cpuinfo_x86 *c, unsigned int cpu)
 	}
 
 	__max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus);
-	logical_packages = 0;
-
-	/*
-	 * Possibly larger than what we need as the number of apic ids per
-	 * package can be smaller than the actual used apic ids.
-	 */
-	max_physical_pkg_id = DIV_ROUND_UP(MAX_LOCAL_APIC, ncpus);
-	size = max_physical_pkg_id * sizeof(unsigned int);
-	physical_to_logical_pkg = kmalloc(size, GFP_KERNEL);
-	memset(physical_to_logical_pkg, 0xff, size);
-	size = BITS_TO_LONGS(max_physical_pkg_id) * sizeof(unsigned long);
-	physical_package_map = kzalloc(size, GFP_KERNEL);
-
 	pr_info("Max logical packages: %u\n", __max_logical_packages);
 
+	logical_packages = 0;
+
 	topology_update_package_map(c->phys_proc_id, cpu);
 }
 
-- 
2.15.0.rc0.39.g2f0e14e64

[PATCH 3/3 v4] x86/smpboot: Fix __max_logical_packages estimate

[Prarit Bhargava]

A system booted with a small number of cores enabled per package
panics because the estimate of __max_logical_packages is too low.
This occurs when the total number of active cores across all packages
is less than the maximum core count for a single package.

ie) On a 4 package system with 20 cores/package where only 4 cores
are enabled on each package, the value of __max_logical_packages is
calculated as DIV_ROUND_UP(16 / 20) = 1 and not 4.

Here's an example of the panic:

     smpboot: Booting Node   1, Processors  #1 OK
     smpboot: Package 1 of CPU 1 exceeds BIOS package data 1.
     ------------[ cut here ]------------
     kernel BUG at arch/x86/kernel/cpu/common.c:1087!
     invalid opcode: 0000 [#1] SMP
     Modules linked in:
     CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.0-rc2+ #4

Calculate __max_logical_packages after the cpu enumeration has completed.
Use the boot cpu's data to extrapolate the number of packages.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Piotr Luc <piotr.luc@intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kernel/smpboot.c | 57 +++++++++--------------------------------------
 1 file changed, 10 insertions(+), 47 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index ca615bc94e82..6307e92f54ae 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -307,12 +307,6 @@ 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++;
 
 	/* Allocate and copy a new array */
@@ -335,46 +329,6 @@ 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);
-
-	logical_packages = 0;
-
-	topology_update_package_map(c->phys_proc_id, cpu);
-}
-
 void __init smp_store_boot_cpu_info(void)
 {
 	int id = 0; /* CPU 0 */
@@ -382,7 +336,7 @@ void __init smp_store_boot_cpu_info(void)
 
 	*c = boot_cpu_data;
 	c->cpu_index = id;
-	smp_init_package_map(c, id);
+	topology_update_package_map(c->phys_proc_id, id);
 }
 
 /*
@@ -1382,7 +1336,16 @@ 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);
-- 
2.15.0.rc0.39.g2f0e14e64

Re: [PATCH 1/3 v4] perf/x86/intel/uncore: Cache logical pkg id in uncore driver

[Thomas Gleixner]

On Wed, 25 Oct 2017, Prarit Bhargava wrote:

> From: Andi Kleen <ak@linux.intel.com>
> 
> The SNB-EP uncore driver is the only user of topology_phys_to_logical_pkg
> in a performance critical path. Change it query the logical pkg ID
> only once at initialization time and then cache it in box structure.

That second sentence needs some care:

  Avoid the lookup in the hotpath and cache the id at initialization
  time. This is also a prerequisite to change the underlying logical
  package management implementation w/o impacting this driver.

Other than that.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

Re: [PATCH 2/3 v4] x86/topology: Avoid wasting 128k for package id array

[Thomas Gleixner]

On Wed, 25 Oct 2017, Prarit Bhargava wrote:
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index b390ff76e58f..f4ab1edf4e24 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -124,8 +124,10 @@ struct cpuinfo_x86 {
>  	u16			booted_cores;
>  	/* Physical processor id: */
>  	u16			phys_proc_id;
> -	/* Logical processor id: */
> +	/* Logical processor (package) id: */
>  	u16			logical_proc_id;
> +	/* Physical package ID */
> +	u16			phys_pkg_id;

How is this new field used aside of being written to and how is it
different from phys_proc_id? AFAICT, it's the same as all callers to
topology_update_package_map() are handing in cpu_data->phys_proc_id.

> +/**
> + * topology_phys_to_logical_pkg - Map a physical package id to a logical
> + *
> + * Returns logical package id or -1 if not found
> + */
> +int topology_phys_to_logical_pkg(unsigned int phys_pkg)
> +{
> +	int log_pkg;
> +
> +	for (log_pkg = 0; log_pkg < logical_packages; log_pkg++)
> +		if (logical_to_physical_pkg_map[log_pkg] == phys_pkg)
> +			return log_pkg;
> +
> +	return -1;
> +}
> +EXPORT_SYMBOL(topology_phys_to_logical_pkg);

....

> +
> +	/* Allocate and copy a new array */
> +	ltp_pkg_map_new = kmalloc(logical_packages * sizeof(u16), GFP_KERNEL);
> +	BUG_ON(!ltp_pkg_map_new);
> +	if (logical_to_physical_pkg_map) {
> +		memcpy(ltp_pkg_map_new, logical_to_physical_pkg_map,
> +		       logical_packages * sizeof(u16));
> +		kfree(logical_to_physical_pkg_map);
>  	}
> -	physical_to_logical_pkg[pkg] = new;
> +	logical_to_physical_pkg_map = ltp_pkg_map_new;

This lacks serialization and is therefore broken against a concurrent
topology_phys_to_logical_pkg() call for obvious reasons. The current user
is probably safe, but this really needs to be fixed now.

Thanks,

	tglx

Re: [PATCH 2/3 v4] x86/topology: Avoid wasting 128k for package id array

[Prarit Bhargava]

On 11/01/2017 12:56 PM, Thomas Gleixner wrote:
> On Wed, 25 Oct 2017, Prarit Bhargava wrote:
>> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
>> index b390ff76e58f..f4ab1edf4e24 100644
>> --- a/arch/x86/include/asm/processor.h
>> +++ b/arch/x86/include/asm/processor.h
>> @@ -124,8 +124,10 @@ struct cpuinfo_x86 {
>>  	u16			booted_cores;
>>  	/* Physical processor id: */
>>  	u16			phys_proc_id;
>> -	/* Logical processor id: */
>> +	/* Logical processor (package) id: */
>>  	u16			logical_proc_id;
>> +	/* Physical package ID */
>> +	u16			phys_pkg_id;
> 
> How is this new field used aside of being written to and how is it
> different from phys_proc_id? AFAICT, it's the same as all callers to
> topology_update_package_map() are handing in cpu_data->phys_proc_id.
> 

I've removed this in v5.

>> +/**
>> + * topology_phys_to_logical_pkg - Map a physical package id to a logical
>> + *
>> + * Returns logical package id or -1 if not found
>> + */
>> +int topology_phys_to_logical_pkg(unsigned int phys_pkg)
>> +{
>> +	int log_pkg;
>> +
>> +	for (log_pkg = 0; log_pkg < logical_packages; log_pkg++)
>> +		if (logical_to_physical_pkg_map[log_pkg] == phys_pkg)
>> +			return log_pkg;
>> +
>> +	return -1;
>> +}
>> +EXPORT_SYMBOL(topology_phys_to_logical_pkg);
> 
> ....
> 
>> +
>> +	/* Allocate and copy a new array */
>> +	ltp_pkg_map_new = kmalloc(logical_packages * sizeof(u16), GFP_KERNEL);
>> +	BUG_ON(!ltp_pkg_map_new);
>> +	if (logical_to_physical_pkg_map) {
>> +		memcpy(ltp_pkg_map_new, logical_to_physical_pkg_map,
>> +		       logical_packages * sizeof(u16));
>> +		kfree(logical_to_physical_pkg_map);
>>  	}
>> -	physical_to_logical_pkg[pkg] = new;
>> +	logical_to_physical_pkg_map = ltp_pkg_map_new;
> 
> This lacks serialization and is therefore broken against a concurrent
> topology_phys_to_logical_pkg() call for obvious reasons. The current user
> is probably safe, but this really needs to be fixed now.

I'm using a spin_lock_irq in v5.

I am finishing testing on 4S & 8S systems now.

P.

> 
> Thanks,
> 
> 	tglx
> 

[PATCH 0/3 v4] Fix panic in logical packages calculation

[Prarit Bhargava]

A system booted with a small number of cores enabled per package
panics because the estimate of __max_logical_packages is too low.
This occurs when the total number of active cores across all packages
is less than the maximum core count for a single package.

Andi noted that the logical_packages calculation wastes 128k on 64-bit
x86 systems and posted patches to fix the allocation.  His patches
result in significant memory size savings, and I have put my
fix on top of those patches.

Here's an example of the panic:

     smpboot: Booting Node   1, Processors  #1 OK
     smpboot: Package 1 of CPU 1 exceeds BIOS package data 1.
     ------------[ cut here ]------------
     kernel BUG at arch/x86/kernel/cpu/common.c:1087!
     invalid opcode: 0000 [#1] SMP
     Modules linked in:
     CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.0-rc2+ #4

This was tested by dropping the number of active cores across
all packages to reproduce the bug above.  Additional testing included
2 socket and 4 socket systems and hotplugging entire sockets in different
order.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Piotr Luc <piotr.luc@intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>

Andi Kleen (2):
  perf/x86/intel/uncore: Cache logical pkg id in uncore driver
  x86/topology: Avoid wasting 128k for package id array

Prarit Bhargava (1):
  x86/smpboot: Fix __max_logical_packages estimate

 arch/x86/events/intel/uncore.c       |   1 +
 arch/x86/events/intel/uncore.h       |   1 +
 arch/x86/events/intel/uncore_snbep.c |   2 +-
 arch/x86/include/asm/processor.h     |   4 +-
 arch/x86/kernel/smpboot.c            | 137 ++++++++++++-----------------------
 5 files changed, 53 insertions(+), 92 deletions(-)

-- 
2.15.0.rc0.39.g2f0e14e64