From 9c5a432a558105d6145b058fad78eb6fcf3d4c38 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Tue, 23 Nov 2021 19:52:31 +1000 Subject: KVM: PPC: Book3S HV P9: Remove subcore HMI handling On POWER9 and newer, rather than the complex HMI synchronisation and subcore state, have each thread un-apply the guest TB offset before calling into the early HMI handler. This allows the subcore state to be avoided, including subcore enter / exit guest, which includes an expensive divide that shows up slightly in profiles. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211123095231.1036501-54-npiggin@gmail.com --- arch/powerpc/kvm/book3s_hv_ras.c | 54 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) (limited to 'arch/powerpc/kvm/book3s_hv_ras.c') diff --git a/arch/powerpc/kvm/book3s_hv_ras.c b/arch/powerpc/kvm/book3s_hv_ras.c index d4bca93b79f6..ccfd96965630 100644 --- a/arch/powerpc/kvm/book3s_hv_ras.c +++ b/arch/powerpc/kvm/book3s_hv_ras.c @@ -136,6 +136,60 @@ void kvmppc_realmode_machine_check(struct kvm_vcpu *vcpu) vcpu->arch.mce_evt = mce_evt; } + +long kvmppc_p9_realmode_hmi_handler(struct kvm_vcpu *vcpu) +{ + struct kvmppc_vcore *vc = vcpu->arch.vcore; + long ret = 0; + + /* + * Unapply and clear the offset first. That way, if the TB was not + * resynced then it will remain in host-offset, and if it was resynced + * then it is brought into host-offset. Then the tb offset is + * re-applied before continuing with the KVM exit. + * + * This way, we don't need to actually know whether not OPAL resynced + * the timebase or do any of the complicated dance that the P7/8 + * path requires. + */ + if (vc->tb_offset_applied) { + u64 new_tb = mftb() - vc->tb_offset_applied; + mtspr(SPRN_TBU40, new_tb); + if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) { + new_tb += 0x1000000; + mtspr(SPRN_TBU40, new_tb); + } + vc->tb_offset_applied = 0; + } + + local_paca->hmi_irqs++; + + if (hmi_handle_debugtrig(NULL) >= 0) { + ret = 1; + goto out; + } + + if (ppc_md.hmi_exception_early) + ppc_md.hmi_exception_early(NULL); + +out: + if (vc->tb_offset) { + u64 new_tb = mftb() + vc->tb_offset; + mtspr(SPRN_TBU40, new_tb); + if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) { + new_tb += 0x1000000; + mtspr(SPRN_TBU40, new_tb); + } + vc->tb_offset_applied = vc->tb_offset; + } + + return ret; +} + +/* + * The following subcore HMI handling is all only for pre-POWER9 CPUs. + */ + /* Check if dynamic split is in force and return subcore size accordingly. */ static inline int kvmppc_cur_subcore_size(void) { -- cgit v1.2.3