1 files changed, 92 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.25/0032-x86-microcode-Sanitize-per-cpu-microcode-reloading-i.patch b/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.25/0032-x86-microcode-Sanitize-per-cpu-microcode-reloading-i.patch
new file mode 100644
index 00000000..824c0394
--- /dev/null
+++ b/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.25/0032-x86-microcode-Sanitize-per-cpu-microcode-reloading-i.patch
@@ -0,0 +1,92 @@
+From 6a7d02f3957e572d5e35fc71df90a3a7311e383d Mon Sep 17 00:00:00 2001
+From: Borislav Petkov <borislav.petkov@amd.com>
+Date: Thu, 21 Jun 2012 14:07:16 +0200
+Subject: [PATCH 32/73] x86, microcode: Sanitize per-cpu microcode reloading
+ interface
+
+commit c9fc3f778a6a215ace14ee556067c73982b6d40f upstream.
+
+Microcode reloading in a per-core manner is a very bad idea for both
+major x86 vendors. And the thing is, we have such interface with which
+we can end up with different microcode versions applied on different
+cores of an otherwise homogeneous wrt (family,model,stepping) system.
+
+So turn off the possibility of doing that per core and allow it only
+system-wide.
+
+This is a minimal fix which we'd like to see in stable too thus the
+more-or-less arbitrary decision to allow system-wide reloading only on
+the BSP:
+
+$ echo 1 > /sys/devices/system/cpu/cpu0/microcode/reload
+...
+
+and disable the interface on the other cores:
+
+$ echo 1 > /sys/devices/system/cpu/cpu23/microcode/reload
+-bash: echo: write error: Invalid argument
+
+Also, allowing the reload only from one CPU (the BSP in
+that case) doesn't allow the reload procedure to degenerate
+into an O(n^2) deal when triggering reloads from all
+/sys/devices/system/cpu/cpuX/microcode/reload sysfs nodes
+simultaneously.
+
+A more generic fix will follow.
+
+Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
+Cc: Peter Zijlstra <peterz@infradead.org>
+Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
+Link: http://lkml.kernel.org/r/1340280437-7718-2-git-send-email-bp@amd64.org
+Signed-off-by: H. Peter Anvin <hpa@zytor.com>
+Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
+---
+ arch/x86/kernel/microcode_core.c |   26 +++++++++++++++++++-------
+ 1 files changed, 19 insertions(+), 7 deletions(-)
+
+diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
+index 19c7af1..29c95d7 100644
+--- a/arch/x86/kernel/microcode_core.c
++++ b/arch/x86/kernel/microcode_core.c
+@@ -297,19 +297,31 @@ static ssize_t reload_store(struct sys_device *dev,
+                            const char *buf, size_t size)
+ {
+        unsigned long val;
+-       int cpu = dev->id;
+-       ssize_t ret = 0;
++       int cpu;
++       ssize_t ret = 0, tmp_ret;
++
++       /* allow reload only from the BSP */
++       if (boot_cpu_data.cpu_index != dev->id)
++               return -EINVAL;
+ 
+        ret = kstrtoul(buf, 0, &val);
+        if (ret)
+                return ret;
+ 
+-       if (val == 1) {
+-               get_online_cpus();
+-               if (cpu_online(cpu))
+-                       ret = reload_for_cpu(cpu);
+-               put_online_cpus();
++       if (val != 1)
++               return size;
++
++       get_online_cpus();
++       for_each_online_cpu(cpu) {
++               tmp_ret = reload_for_cpu(cpu);
++               if (tmp_ret != 0)
++                       pr_warn("Error reloading microcode on CPU %d\n", cpu);
++
++               /* save retval of the first encountered reload error */
++               if (!ret)
++                       ret = tmp_ret;
+        }
++       put_online_cpus();
+ 
+        if (!ret)
+                ret = size;
+-- 
+1.7.7.6
+