Paul Mackerras <paulus@xxxxxxxxxx> writes:
> On POWER9, the msgsnd instruction is able to send interrupts to
> other cores, as well as other threads on the local core. Since
> msgsnd is generally simpler and faster than sending an IPI via the
> XICS, we use msgsnd for all IPIs sent by KVM on POWER9.
>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
> ---
> arch/powerpc/kvm/book3s_hv.c | 11 ++++++++++-
> arch/powerpc/kvm/book3s_hv_builtin.c | 10 ++++++++--
> 2 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 8395a7f..ace89df 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -147,12 +147,21 @@ static inline struct kvm_vcpu *next_runnable_thread(struct kvmppc_vcore *vc,
>
> static bool kvmppc_ipi_thread(int cpu)
> {
> + unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
> +
> + /* On POWER9 we can use msgsnd to IPI any cpu */
> + if (cpu_has_feature(CPU_FTR_ARCH_300)) {
> + msg |= get_hard_smp_processor_id(cpu);
> + smp_mb();
> + __asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
> + return true;
> + }
> +
> /* On POWER8 for IPIs to threads in the same core, use msgsnd */
> if (cpu_has_feature(CPU_FTR_ARCH_207S)) {
> preempt_disable();
> if (cpu_first_thread_sibling(cpu) ==
> cpu_first_thread_sibling(smp_processor_id())) {
> - unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
> msg |= cpu_thread_in_core(cpu);
> smp_mb();
> __asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
> diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c
> index 0c84d6b..37ed045 100644
> --- a/arch/powerpc/kvm/book3s_hv_builtin.c
> +++ b/arch/powerpc/kvm/book3s_hv_builtin.c
> @@ -205,12 +205,18 @@ static inline void rm_writeb(unsigned long paddr, u8 val)
> void kvmhv_rm_send_ipi(int cpu)
> {
> unsigned long xics_phys;
> + unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
>
> - /* On POWER8 for IPIs to threads in the same core, use msgsnd */
> + /* On POWER9 we can use msgsnd for any destination cpu. */
> + if (cpu_has_feature(CPU_FTR_ARCH_300)) {
> + msg |= get_hard_smp_processor_id(cpu);
> + __asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
> + return;
Do we need a "sync" there before msgsnd ?
> + }
> + /* On POWER8 for IPIs to threads in the same core, use msgsnd. */
> if (cpu_has_feature(CPU_FTR_ARCH_207S) &&
> cpu_first_thread_sibling(cpu) ==
> cpu_first_thread_sibling(raw_smp_processor_id())) {
> - unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
> msg |= cpu_thread_in_core(cpu);
> __asm__ __volatile__ (PPC_MSGSND(%0) : : "r" (msg));
> return;
> --
> 2.7.4
>
> --
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