Re: [PATCH v2 16/37] KVM: PPC: Book3S HV P9: Stop handling hcalls in real-mode in the P9 path
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2021-02-26 23:59:45
Excerpts from Cédric Le Goater's message of February 26, 2021 12:51 am:
On 2/25/21 2:46 PM, Nicholas Piggin wrote:quoted
In the interest of minimising the amount of code that is run in "real-mode", don't handle hcalls in real mode in the P9 path. POWER8 and earlier are much more expensive to exit from HV real mode and switch to host mode, because on those processors HV interrupts get to the hypervisor with the MMU off, and the other threads in the core need to be pulled out of the guest, and SLBs all need to be saved, ERATs invalidated, and host SLB reloaded before the MMU is re-enabled in host mode. Hash guests also require a lot of hcalls to run. The XICS interrupt controller requires hcalls to run. By contrast, POWER9 has independent thread switching, and in radix mode the hypervisor is already in a host virtual memory mode when the HV interrupt is taken. Radix + xive guests don't need hcalls to handle interrupts or manage translations. So it's much less important to handle hcalls in real mode in P9. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/include/asm/kvm_ppc.h | 5 +++++ arch/powerpc/kvm/book3s_hv.c | 25 ++++++++++++++++++++++--- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 5 +++++ arch/powerpc/kvm/book3s_xive.c | 25 +++++++++++++++++++++++++ 4 files changed, 57 insertions(+), 3 deletions(-)diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h index 73b1ca5a6471..db6646c2ade2 100644 --- a/arch/powerpc/include/asm/kvm_ppc.h +++ b/arch/powerpc/include/asm/kvm_ppc.h@@ -607,6 +607,7 @@ extern void kvmppc_free_pimap(struct kvm *kvm); extern int kvmppc_xics_rm_complete(struct kvm_vcpu *vcpu, u32 hcall); extern void kvmppc_xics_free_icp(struct kvm_vcpu *vcpu); extern int kvmppc_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd); +extern int kvmppc_xive_xics_hcall(struct kvm_vcpu *vcpu, u32 req); extern u64 kvmppc_xics_get_icp(struct kvm_vcpu *vcpu); extern int kvmppc_xics_set_icp(struct kvm_vcpu *vcpu, u64 icpval); extern int kvmppc_xics_connect_vcpu(struct kvm_device *dev,@@ -639,6 +640,8 @@ static inline int kvmppc_xics_enabled(struct kvm_vcpu *vcpu) static inline void kvmppc_xics_free_icp(struct kvm_vcpu *vcpu) { } static inline int kvmppc_xics_hcall(struct kvm_vcpu *vcpu, u32 cmd) { return 0; } +static inline int kvmppc_xive_xics_hcall(struct kvm_vcpu *vcpu, u32 req) + { return 0; } #endif #ifdef CONFIG_KVM_XIVE@@ -673,6 +676,7 @@ extern int kvmppc_xive_set_irq(struct kvm *kvm, int irq_source_id, u32 irq, int level, bool line_status); extern void kvmppc_xive_push_vcpu(struct kvm_vcpu *vcpu); extern void kvmppc_xive_pull_vcpu(struct kvm_vcpu *vcpu); +extern void kvmppc_xive_cede_vcpu(struct kvm_vcpu *vcpu);I can not find this routine. Is it missing or coming later in the patchset ?
Yeah it leaked into a later patch but it belongs here. I'll fix it. Thanks, Nick