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>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 5bef931f8b14..2d228fc9b4b7 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -244,6 +244,9 @@ do {                                                            \
 
 #define write_rdtscp_aux(val) wrmsr(0xc0000103, (val), 0)
 
+struct msr *msrs_alloc(void);
+void msrs_free(struct msr *msrs);
+
 #ifdef CONFIG_SMP
 int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
 int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);