From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> Remove APIC_BUS_FREQUENCY and calculate it based on nanoseconds per APIC bus cycle. APIC_BUS_FREQUENCY is used only for HV_X64_MSR_APIC_FREQUENCY. The MSR is not frequently read, calculate it every time. There are two constants related to the APIC bus frequency: APIC_BUS_FREQUENCY and APIC_BUS_CYCLE_NS. Only one value is required because one can be calculated from the other: APIC_BUS_CYCLES_NS = 1000 * 1000 * 1000 / APIC_BUS_FREQUENCY. Remove APIC_BUS_FREQUENCY and instead calculate it when needed. This prepares for support of configurable APIC bus frequency by requiring to change only a single variable. Suggested-by: Maxim Levitsky <maximlevitsky@xxxxxxxxx> Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> Reviewed-by: Maxim Levitsky <maximlevitsky@xxxxxxxxx> Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> Reviewed-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx> [reinette: rework changelog] Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> --- Changes v5: - Add Rick's Reviewed-by tag. Changes v4: - Modify subject to match custom: "KVM: x86/hyperv:" -> "KVM: x86: hyper-v:" and use standard capitalization for Hyper-V ("hyper-v" -> "Hyper-V"). - Rework changelog to remove pronouns ("we"). - Change logic in commit log: "APIC bus cycles per NS" -> "nanoseconds per APIC bus cycle". - Fix typos. (Maxim and Xiaoyao) - Add Maxim and Xiaoyao's Reviewed-by tags. - Add Maxim's "Suggested-by". Changes v3: - Newly added according to Maxim Levitsky suggestion. --- arch/x86/kvm/hyperv.c | 2 +- arch/x86/kvm/lapic.h | 1 - 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 8a47f8541eab..1030701db967 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -1737,7 +1737,7 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, data = (u64)vcpu->arch.virtual_tsc_khz * 1000; break; case HV_X64_MSR_APIC_FREQUENCY: - data = APIC_BUS_FREQUENCY; + data = div64_u64(1000000000ULL, APIC_BUS_CYCLE_NS); break; default: kvm_pr_unimpl_rdmsr(vcpu, msr); diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index 0a0ea4b5dd8c..a20cb006b6c8 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -17,7 +17,6 @@ #define APIC_DEST_MASK 0x800 #define APIC_BUS_CYCLE_NS 1 -#define APIC_BUS_FREQUENCY (1000000000ULL / APIC_BUS_CYCLE_NS) #define APIC_BROADCAST 0xFF #define X2APIC_BROADCAST 0xFFFFFFFFul -- 2.34.1