x86, msr: Add support for non-contiguous cpumasks
The current rd/wrmsr_on_cpus helpers assume that the supplied
cpumasks are contiguous. However, there are machines out there
like some K8 multinode Opterons which have a non-contiguous core
enumeration on each node (e.g. cores 0,2 on node 0 instead of 0,1), see
http://www.gossamer-threads.com/lists/linux/kernel/1160268.
This patch fixes out-of-bounds writes (see URL above) by adding per-CPU
msr structs which are used on the respective cores.
Additionally, two helpers, msrs_{alloc,free}, are provided for use by
the callers of the MSR accessors.
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Aristeu Rozanski <aris@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Doug Thompson <dougthompson@xmission.com>
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20091211171440.GD31998@aftab>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/lib/msr.c b/arch/x86/lib/msr.c
index 41628b1..8728341 100644
--- a/arch/x86/lib/msr.c
+++ b/arch/x86/lib/msr.c
@@ -7,7 +7,6 @@
u32 msr_no;
struct msr reg;
struct msr *msrs;
- int off;
int err;
};
@@ -18,7 +17,7 @@
int this_cpu = raw_smp_processor_id();
if (rv->msrs)
- reg = &rv->msrs[this_cpu - rv->off];
+ reg = per_cpu_ptr(rv->msrs, this_cpu);
else
reg = &rv->reg;
@@ -32,7 +31,7 @@
int this_cpu = raw_smp_processor_id();
if (rv->msrs)
- reg = &rv->msrs[this_cpu - rv->off];
+ reg = per_cpu_ptr(rv->msrs, this_cpu);
else
reg = &rv->reg;
@@ -80,7 +79,6 @@
memset(&rv, 0, sizeof(rv));
- rv.off = cpumask_first(mask);
rv.msrs = msrs;
rv.msr_no = msr_no;
@@ -120,6 +118,26 @@
}
EXPORT_SYMBOL(wrmsr_on_cpus);
+struct msr *msrs_alloc(void)
+{
+ struct msr *msrs = NULL;
+
+ msrs = alloc_percpu(struct msr);
+ if (!msrs) {
+ pr_warning("%s: error allocating msrs\n", __func__);
+ return NULL;
+ }
+
+ return msrs;
+}
+EXPORT_SYMBOL(msrs_alloc);
+
+void msrs_free(struct msr *msrs)
+{
+ free_percpu(msrs);
+}
+EXPORT_SYMBOL(msrs_free);
+
/* These "safe" variants are slower and should be used when the target MSR
may not actually exist. */
static void __rdmsr_safe_on_cpu(void *info)