From aaffcfd1e82d3378538408d0310b7424b98d8f81 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Mon, 23 Jul 2018 14:39:52 +0800 Subject: [PATCH] KVM: X86: Implement PV IPIs in linux guest MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Implement paravirtual apic hooks to enable PV IPIs for KVM if the "send IPI" hypercall is available. The hypercall lets a guest send IPIs, with at most 128 destinations per hypercall in 64-bit mode and 64 vCPUs per hypercall in 32-bit mode. Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Vitaly Kuznetsov Signed-off-by: Wanpeng Li Signed-off-by: Paolo Bonzini --- arch/x86/include/uapi/asm/kvm_para.h | 1 + arch/x86/kernel/kvm.c | 96 ++++++++++++++++++++++++++++ include/uapi/linux/kvm_para.h | 1 + 3 files changed, 98 insertions(+) diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h index 0ede697c3961..19980ec1a316 100644 --- a/arch/x86/include/uapi/asm/kvm_para.h +++ b/arch/x86/include/uapi/asm/kvm_para.h @@ -28,6 +28,7 @@ #define KVM_FEATURE_PV_UNHALT 7 #define KVM_FEATURE_PV_TLB_FLUSH 9 #define KVM_FEATURE_ASYNC_PF_VMEXIT 10 +#define KVM_FEATURE_PV_SEND_IPI 11 #define KVM_HINTS_REALTIME 0 diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 39d79720380f..62cbd089f709 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -454,6 +454,98 @@ static void __init sev_map_percpu_data(void) } #ifdef CONFIG_SMP +#define KVM_IPI_CLUSTER_SIZE (2 * BITS_PER_LONG) + +static void __send_ipi_mask(const struct cpumask *mask, int vector) +{ + unsigned long flags; + int cpu, apic_id, icr; + int min = 0, max = 0; +#ifdef CONFIG_X86_64 + __uint128_t ipi_bitmap = 0; +#else + u64 ipi_bitmap = 0; +#endif + + if (cpumask_empty(mask)) + return; + + local_irq_save(flags); + + switch (vector) { + default: + icr = APIC_DM_FIXED | vector; + break; + case NMI_VECTOR: + icr = APIC_DM_NMI; + break; + } + + for_each_cpu(cpu, mask) { + apic_id = per_cpu(x86_cpu_to_apicid, cpu); + if (!ipi_bitmap) { + min = max = apic_id; + } else if (apic_id < min && max - apic_id < KVM_IPI_CLUSTER_SIZE) { + ipi_bitmap <<= min - apic_id; + min = apic_id; + } else if (apic_id < min + KVM_IPI_CLUSTER_SIZE) { + max = apic_id < max ? max : apic_id; + } else { + kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, + (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); + min = max = apic_id; + ipi_bitmap = 0; + } + __set_bit(apic_id - min, (unsigned long *)&ipi_bitmap); + } + + if (ipi_bitmap) { + kvm_hypercall4(KVM_HC_SEND_IPI, (unsigned long)ipi_bitmap, + (unsigned long)(ipi_bitmap >> BITS_PER_LONG), min, icr); + } + + local_irq_restore(flags); +} + +static void kvm_send_ipi_mask(const struct cpumask *mask, int vector) +{ + __send_ipi_mask(mask, vector); +} + +static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector) +{ + unsigned int this_cpu = smp_processor_id(); + struct cpumask new_mask; + const struct cpumask *local_mask; + + cpumask_copy(&new_mask, mask); + cpumask_clear_cpu(this_cpu, &new_mask); + local_mask = &new_mask; + __send_ipi_mask(local_mask, vector); +} + +static void kvm_send_ipi_allbutself(int vector) +{ + kvm_send_ipi_mask_allbutself(cpu_online_mask, vector); +} + +static void kvm_send_ipi_all(int vector) +{ + __send_ipi_mask(cpu_online_mask, vector); +} + +/* + * Set the IPI entry points + */ +static void kvm_setup_pv_ipi(void) +{ + apic->send_IPI_mask = kvm_send_ipi_mask; + apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself; + apic->send_IPI_allbutself = kvm_send_ipi_allbutself; + apic->send_IPI_all = kvm_send_ipi_all; + pr_info("KVM setup pv IPIs\n"); +} + static void __init kvm_smp_prepare_cpus(unsigned int max_cpus) { native_smp_prepare_cpus(max_cpus); @@ -626,6 +718,10 @@ static uint32_t __init kvm_detect(void) static void __init kvm_apic_init(void) { +#if defined(CONFIG_SMP) + if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI)) + kvm_setup_pv_ipi(); +#endif } static void __init kvm_init_platform(void) diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h index f3893ef82b65..6c0ce49931e5 100644 --- a/include/uapi/linux/kvm_para.h +++ b/include/uapi/linux/kvm_para.h @@ -27,6 +27,7 @@ #define KVM_HC_MIPS_EXIT_VM 7 #define KVM_HC_MIPS_CONSOLE_OUTPUT 8 #define KVM_HC_CLOCK_PAIRING 9 +#define KVM_HC_SEND_IPI 10 /* * hypercalls use architecture specific