Wei Liu <wei.liu@xxxxxxxxxx> writes:
> This is a new variant which removes `self' cpu from the vpset. It will
> be used in Hyper-V enlightened IPI code.
>
> Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx>
> ---
> Provide a new variant instead of adding a new parameter because it makes
> it easier to backport -- we don't need to fix the users of
> cpumask_to_vpset.
> ---
> include/asm-generic/mshyperv.h | 20 ++++++++++++++++++--
> 1 file changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index 9a000ba2bb75..d89690ee95aa 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -184,10 +184,12 @@ static inline int hv_cpu_number_to_vp_number(int cpu_number)
> return hv_vp_index[cpu_number];
> }
>
> -static inline int cpumask_to_vpset(struct hv_vpset *vpset,
> - const struct cpumask *cpus)
> +static inline int cpumask_to_vpset_ex(struct hv_vpset *vpset,
I'd suggest to avoid '_ex' suffix as we use it for 'extended hypercalls'
(e.g. __send_ipi_mask_ex). Assuming nobody needs to call
cpumask_to_vpset_ex() directly, should we just go with
__cpumask_to_vpset() instead?
> + const struct cpumask *cpus,
> + bool exclude_self)
> {
> int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1;
> + int this_cpu = smp_processor_id();
>
> /* valid_bank_mask can represent up to 64 banks */
> if (hv_max_vp_index / 64 >= 64)
> @@ -205,6 +207,8 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset,
> * Some banks may end up being empty but this is acceptable.
> */
> for_each_cpu(cpu, cpus) {
> + if (exclude_self && cpu == this_cpu)
> + continue;
> vcpu = hv_cpu_number_to_vp_number(cpu);
> if (vcpu == VP_INVAL)
> return -1;
> @@ -219,6 +223,18 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset,
> return nr_bank;
> }
>
> +static inline int cpumask_to_vpset(struct hv_vpset *vpset,
> + const struct cpumask *cpus)
> +{
> + return cpumask_to_vpset_ex(vpset, cpus, false);
> +}
> +
> +static inline int cpumask_to_vpset_noself(struct hv_vpset *vpset,
> + const struct cpumask *cpus)
> +{
> + return cpumask_to_vpset_ex(vpset, cpus, true);
We need to make sure this is called with preemption disabled. We
could've just swapped smp_processor_id() for get_cpu() in
cpumask_to_vpset_ex() but this is hardly a solution: we can get
preempted right after put_cpu() so it's really the caller of this
function which needs to be protected.
TL;DR: I suggest we add 'WARN_ON_ONCE(preemptible());' or something like
this here to catch wrong usage.
> +}
> +
> void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die);
> bool hv_is_hyperv_initialized(void);
> bool hv_is_hibernation_supported(void);
--
Vitaly
