Messages in this thread Patch in this message | | | From | Borislav Petkov <> | Subject | [PATCH 1/3] x86/msr: Pass a single MSR value to __rwmsr_on_cpus() too | Date | Wed, 10 Jun 2020 13:00:35 +0200 |
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From: Borislav Petkov <bp@suse.de>
__rwmsr_on_cpus() is the low-level worker function which is called by the exported {rd,wr}msr_on_cpus() when an MSR is supposed to be set with values for CPUs or an MSR is supposed to be read from CPUs into an array of percpu variables in @msrs.
The low-level machinery supports also passing a single MSR value for the single CPU {rd,wr}msr_on_cpu() handlers.
Pass that value to __rwmsr_on_cpus() too and enforce a mutually exclusive either a single MSR value "XOR" an array of per-CPU MSR values.
This is the prerequisite for supporting writing the same MSR value on multiple CPUs.
Signed-off-by: Borislav Petkov <bp@suse.de> --- arch/x86/lib/msr-smp.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/x86/lib/msr-smp.c b/arch/x86/lib/msr-smp.c index fee8b9c0520c..15e1157d6b29 100644 --- a/arch/x86/lib/msr-smp.c +++ b/arch/x86/lib/msr-smp.c @@ -97,7 +97,7 @@ int wrmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 q) EXPORT_SYMBOL(wrmsrl_on_cpu); static void __rwmsr_on_cpus(const struct cpumask *mask, u32 msr_no, - struct msr *msrs, + struct msr *msrs, u64 reg_val, void (*msr_func) (void *info)) { struct msr_info rv; @@ -105,8 +105,13 @@ static void __rwmsr_on_cpus(const struct cpumask *mask, u32 msr_no, memset(&rv, 0, sizeof(rv)); + /* Can't have both. */ + if (WARN_ON(msrs && reg_val)) + return; + rv.msrs = msrs; rv.msr_no = msr_no; + rv.reg.q = reg_val; this_cpu = get_cpu(); @@ -126,7 +131,7 @@ static void __rwmsr_on_cpus(const struct cpumask *mask, u32 msr_no, */ void rdmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr *msrs) { - __rwmsr_on_cpus(mask, msr_no, msrs, __rdmsr_on_cpu); + __rwmsr_on_cpus(mask, msr_no, msrs, 0, __rdmsr_on_cpu); } EXPORT_SYMBOL(rdmsr_on_cpus); @@ -140,7 +145,7 @@ EXPORT_SYMBOL(rdmsr_on_cpus); */ void wrmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr *msrs) { - __rwmsr_on_cpus(mask, msr_no, msrs, __wrmsr_on_cpu); + __rwmsr_on_cpus(mask, msr_no, msrs, 0, __wrmsr_on_cpu); } EXPORT_SYMBOL(wrmsr_on_cpus); -- 2.21.0
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