| Message ID | 1479454122-26994-11-git-send-email-paulus@ozlabs.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Paul Mackerras <paulus@ozlabs.org> 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@ozlabs.org> > --- > 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 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Nov 18, 2016 at 08:17:25PM +0530, Aneesh Kumar K.V wrote: > Paul Mackerras <paulus@ozlabs.org> 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@ozlabs.org> > > --- > > 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_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 ? The comment just above this function says: /* * Send an interrupt or message to another CPU. * This can only be called in real mode. * The caller needs to include any barrier needed to order writes * to memory vs. the IPI/message. */ so no. In fact all of its callers do smp_mb() before calling it. (And no we don't want to move the smp_mb() into kvmhv_rm_send_ipi(); see kvmhv_interrupt_vcore() for why.) Paul. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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; + } + /* 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;
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@ozlabs.org> --- arch/powerpc/kvm/book3s_hv.c | 11 ++++++++++- arch/powerpc/kvm/book3s_hv_builtin.c | 10 ++++++++-- 2 files changed, 18 insertions(+), 3 deletions(-)