From 60283df7ac26a4fe2d56631ca2946e04725e7eaf Mon Sep 17 00:00:00 2001
From: Richard Weinberger <richard@nod.at>
Date: Tue, 14 Jan 2014 08:44:47 +0100
Subject: x86/apic: Read Error Status Register correctly
Currently we do a read, a dummy write and a final read to fetch
the error code. The value from the final read is taken.
This is not the recommended way and leads to corrupted/lost ESR
values.
Intel(c) 64 and IA-32 Architectures Software Developer's Manual,
Combined Volumes 1, 2ABC, 3ABC, Section 10.5.3 states:
Before attempt to read from the ESR, software should first
write to it. (The value written does not affect the values read
subsequently; only zero may be written in x2APIC mode.) This
write clears any previously logged errors and updates the ESR
with any errors detected since the last write to the ESR.
This write also rearms the APIC error interrupt triggering
mechanism.
This patch removes the first read such that we are conform with
the manual.
On my (very old) Pentium MMX SMP system this patch fixes the
issue that APIC errors:
a) are not always reported and
b) are reported with false error numbers.
Signed-off-by: Richard Weinberger <richard@nod.at>
Cc: seiji.aguchi@hds.com
Cc: rientjes@google.com
Cc: konrad.wilk@oracle.com
Cc: bp@alien8.de
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1389685487-20872-1-git-send-email-richard@nod.at
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/apic/apic.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
(limited to 'arch/x86/kernel/apic/apic.c')
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index d278736bf77..4ec1dd64022 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1968,7 +1968,7 @@ __visible void smp_trace_spurious_interrupt(struct pt_regs *regs)
*/
static inline void __smp_error_interrupt(struct pt_regs *regs)
{
- u32 v0, v1;
+ u32 v;
u32 i = 0;
static const char * const error_interrupt_reason[] = {
"Send CS error", /* APIC Error Bit 0 */
@@ -1982,21 +1982,20 @@ static inline void __smp_error_interrupt(struct pt_regs *regs)
};
/* First tickle the hardware, only then report what went on. -- REW */
- v0 = apic_read(APIC_ESR);
apic_write(APIC_ESR, 0);
- v1 = apic_read(APIC_ESR);
+ v = apic_read(APIC_ESR);
ack_APIC_irq();
atomic_inc(&irq_err_count);
- apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x(%02x)",
- smp_processor_id(), v0 , v1);
+ apic_printk(APIC_DEBUG, KERN_DEBUG "APIC error on CPU%d: %02x",
+ smp_processor_id(), v);
- v1 = v1 & 0xff;
- while (v1) {
- if (v1 & 0x1)
+ v &= 0xff;
+ while (v) {
+ if (v & 0x1)
apic_printk(APIC_DEBUG, KERN_CONT " : %s", error_interrupt_reason[i]);
i++;
- v1 >>= 1;
+ v >>= 1;
}
apic_printk(APIC_DEBUG, KERN_CONT "\n");
--
cgit v1.2.3-70-g09d2
From 151e0c7de616310f95393d9306903900fcd8b277 Mon Sep 17 00:00:00 2001
From: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Date: Wed, 15 Jan 2014 15:44:58 +0900
Subject: x86, apic, kexec: Add disable_cpu_apicid kernel parameter
Add disable_cpu_apicid kernel parameter. To use this kernel parameter,
specify an initial APIC ID of the corresponding CPU you want to
disable.
This is mostly used for the kdump 2nd kernel to disable BSP to wake up
multiple CPUs without causing system reset or hang due to sending INIT
from AP to BSP.
Kdump users first figure out initial APIC ID of the BSP, CPU0 in the
1st kernel, for example from /proc/cpuinfo and then set up this kernel
parameter for the 2nd kernel using the obtained APIC ID.
However, doing this procedure at each boot time manually is awkward,
which should be automatically done by user-land service scripts, for
example, kexec-tools on fedora/RHEL distributions.
This design is more flexible than disabling BSP in kernel boot time
automatically in that in kernel boot time we have no choice but
referring to ACPI/MP table to obtain initial APIC ID for BSP, meaning
that the method is not applicable to the systems without such BIOS
tables.
One assumption behind this design is that users get initial APIC ID of
the BSP in still healthy state and so BSP is uniquely kept in
CPU0. Thus, through the kernel parameter, only one initial APIC ID can
be specified.
In a comparison with disabled_cpu_apicid, we use read_apic_id(), not
boot_cpu_physical_apicid, because on some platforms, the variable is
modified to the apicid reported as BSP through MP table and this
function is executed with the temporarily modified
boot_cpu_physical_apicid. As a result, disabled_cpu_apicid kernel
parameter doesn't work well for apicids of APs.
Fixing the wrong handling of boot_cpu_physical_apicid requires some
reviews and tests beyond some platforms and it could take some
time. The fix here is a kind of workaround to focus on the main topic
of this patch.
Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Link: http://lkml.kernel.org/r/20140115064458.1545.38775.stgit@localhost6.localdomain6
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
Documentation/kernel-parameters.txt | 9 +++++++
arch/x86/kernel/apic/apic.c | 49 +++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+)
(limited to 'arch/x86/kernel/apic/apic.c')
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b9e9bd85429..6fdbf8c968e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -774,6 +774,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
disable= [IPV6]
See Documentation/networking/ipv6.txt.
+ disable_cpu_apicid= [X86,APIC,SMP]
+ Format: <int>
+ The number of initial APIC ID for the
+ corresponding CPU to be disabled at boot,
+ mostly used for the kdump 2nd kernel to
+ disable BSP to wake up multiple CPUs without
+ causing system reset or hang due to sending
+ INIT from AP to BSP.
+
disable_ddw [PPC/PSERIES]
Disable Dynamic DMA Window support. Use this if
to workaround buggy firmware.
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 4ec1dd64022..e78ab8c8ac2 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -74,6 +74,13 @@ unsigned int max_physical_apicid;
*/
physid_mask_t phys_cpu_present_map;
+/*
+ * Processor to be disabled specified by kernel parameter
+ * disable_cpu_apicid=<int>, mostly used for the kdump 2nd kernel to
+ * avoid undefined behaviour caused by sending INIT from AP to BSP.
+ */
+unsigned int disabled_cpu_apicid = BAD_APICID;
+
/*
* Map cpu index to physical APIC ID
*/
@@ -2113,6 +2120,39 @@ int generic_processor_info(int apicid, int version)
bool boot_cpu_detected = physid_isset(boot_cpu_physical_apicid,
phys_cpu_present_map);
+ /*
+ * boot_cpu_physical_apicid is designed to have the apicid
+ * returned by read_apic_id(), i.e, the apicid of the
+ * currently booting-up processor. However, on some platforms,
+ * it is temporarilly modified by the apicid reported as BSP
+ * through MP table. Concretely:
+ *
+ * - arch/x86/kernel/mpparse.c: MP_processor_info()
+ * - arch/x86/mm/amdtopology.c: amd_numa_init()
+ * - arch/x86/platform/visws/visws_quirks.c: MP_processor_info()
+ *
+ * This function is executed with the modified
+ * boot_cpu_physical_apicid. So, disabled_cpu_apicid kernel
+ * parameter doesn't work to disable APs on kdump 2nd kernel.
+ *
+ * Since fixing handling of boot_cpu_physical_apicid requires
+ * another discussion and tests on each platform, we leave it
+ * for now and here we use read_apic_id() directly in this
+ * function, generic_processor_info().
+ */
+ if (disabled_cpu_apicid != BAD_APICID &&
+ disabled_cpu_apicid != read_apic_id() &&
+ disabled_cpu_apicid == apicid) {
+ int thiscpu = num_processors + disabled_cpus;
+
+ pr_warning("ACPI: Disabling requested cpu."
+ " Processor %d/0x%x ignored.\n",
+ thiscpu, apicid);
+
+ disabled_cpus++;
+ return -ENODEV;
+ }
+
/*
* If boot cpu has not been detected yet, then only allow upto
* nr_cpu_ids - 1 processors and keep one slot free for boot cpu
@@ -2591,3 +2631,12 @@ static int __init lapic_insert_resource(void)
* that is using request_resource
*/
late_initcall(lapic_insert_resource);
+
+static int __init apic_set_disabled_cpu_apicid(char *arg)
+{
+ if (!arg || !get_option(&arg, &disabled_cpu_apicid))
+ return -EINVAL;
+
+ return 0;
+}
+early_param("disable_cpu_apicid", apic_set_disabled_cpu_apicid);
--
cgit v1.2.3-70-g09d2
From 5b4d1dbc24bb6fd7179ada0f47be34e27e64decb Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Wed, 15 Jan 2014 13:02:08 -0800
Subject: x86, apic: Make disabled_cpu_apicid static read_mostly, fix typos
Make disabled_cpu_apicid static and read_mostly, and fix a couple of
typos.
Reported-by: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/20140115182511.GA22737@gmail.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
---
arch/x86/kernel/apic/apic.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
(limited to 'arch/x86/kernel/apic/apic.c')
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index e78ab8c8ac2..7f26c9a70a9 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -79,7 +79,7 @@ physid_mask_t phys_cpu_present_map;
* disable_cpu_apicid=<int>, mostly used for the kdump 2nd kernel to
* avoid undefined behaviour caused by sending INIT from AP to BSP.
*/
-unsigned int disabled_cpu_apicid = BAD_APICID;
+static unsigned int disabled_cpu_apicid __read_mostly = BAD_APICID;
/*
* Map cpu index to physical APIC ID
@@ -2124,7 +2124,7 @@ int generic_processor_info(int apicid, int version)
* boot_cpu_physical_apicid is designed to have the apicid
* returned by read_apic_id(), i.e, the apicid of the
* currently booting-up processor. However, on some platforms,
- * it is temporarilly modified by the apicid reported as BSP
+ * it is temporarily modified by the apicid reported as BSP
* through MP table. Concretely:
*
* - arch/x86/kernel/mpparse.c: MP_processor_info()
@@ -2145,7 +2145,7 @@ int generic_processor_info(int apicid, int version)
disabled_cpu_apicid == apicid) {
int thiscpu = num_processors + disabled_cpus;
- pr_warning("ACPI: Disabling requested cpu."
+ pr_warning("APIC: Disabling requested cpu."
" Processor %d/0x%x ignored.\n",
thiscpu, apicid);
--
cgit v1.2.3-70-g09d2