Wanpeng Li <kernellwp@xxxxxxxxx> writes:
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>
> Implement PV IPIs in guest kernel.
>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
> Cc: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> ---
> arch/x86/kernel/kvm.c | 99 +++++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/kvm_para.h | 1 +
> 2 files changed, 100 insertions(+)
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index 5b2300b..7e3ee25 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -47,6 +47,7 @@
> #include <asm/hypervisor.h>
> #include <asm/kvm_guest.h>
>
> +static struct apic orig_apic;
> static int kvmapf = 1;
>
> static int __init parse_no_kvmapf(char *arg)
> @@ -454,6 +455,89 @@ static void __init sev_map_percpu_data(void)
> }
>
> #ifdef CONFIG_SMP
> +
> +#ifdef CONFIG_X86_64
> +static bool __send_ipi_mask(const struct cpumask *mask, int vector)
> +{
> + unsigned long flags, ipi_bitmap_low = 0, ipi_bitmap_high = 0, icr = 0;
> + int cpu, apic_id, ret = 1;
> +
> + if (cpumask_empty(mask))
> + return true;
> +
> + local_irq_save(flags);
> +
> + for_each_cpu(cpu, mask) {
> + apic_id = per_cpu(x86_cpu_to_apicid, cpu);
> + if (apic_id < BITS_PER_LONG)
> + __set_bit(apic_id, &ipi_bitmap_low);
> + else if (apic_id < 2 * BITS_PER_LONG)
> + __set_bit(apic_id - BITS_PER_LONG, &ipi_bitmap_high);
> + else
> + goto ipi_mask_done;
Nit:
Both the fact that we don't set 'ret' here and the fact that the label
is named 'ipi_mask_done' -- which sounds like 'all OK' at least to me --
contribute to the feeling that we just skip sending IPIs in some cases.
I would prefer to see something like
else {
ret = -EFAULT;
goto irq_restore_exit;
}
> + }
> +
> + switch (vector) {
> + default:
> + icr = APIC_DM_FIXED | vector;
> + break;
> + case NMI_VECTOR:
> + icr = APIC_DM_NMI;
> + break;
> + }
> +
> + ret = kvm_hypercall3(KVM_HC_SEND_IPI, ipi_bitmap_low, ipi_bitmap_high, icr);
> +
> +ipi_mask_done:
> + local_irq_restore(flags);
> + return ((ret == 0) ? true : false);
... and why in the first place do we need to make this function return
'bool' then? Let's just make it return 'int'.
> +}
> +
> +static void kvm_send_ipi_mask(const struct cpumask *mask, int vector)
> +{
> + if (!__send_ipi_mask(mask, vector))
> + orig_apic.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;
> + if (!__send_ipi_mask(local_mask, vector))
> + orig_apic.send_IPI_mask_allbutself(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)
> +{
> + if (!__send_ipi_mask(cpu_online_mask, vector))
> + orig_apic.send_IPI_all(vector);
> +}
> +
> +/*
> + * Set the IPI entry points
> + */
> +static void kvm_setup_pv_ipi(void)
> +{
> + orig_apic = *apic;
> +
> + 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");
> +}
> +#endif
> +
> static void __init kvm_smp_prepare_cpus(unsigned int max_cpus)
> {
> native_smp_prepare_cpus(max_cpus);
> @@ -624,12 +708,27 @@ static uint32_t __init kvm_detect(void)
> return kvm_cpuid_base();
> }
>
> +static void __init kvm_apic_init(void)
> +{
> +#if defined(CONFIG_SMP) && defined(CONFIG_X86_64)
> + if (kvm_para_has_feature(KVM_FEATURE_PV_SEND_IPI) &&
> + num_possible_cpus() <= 2 * BITS_PER_LONG)
> + kvm_setup_pv_ipi();
> +#endif
> +}
> +
> +static void __init kvm_init_platform(void)
> +{
> + x86_platform.apic_post_init = kvm_apic_init;
> +}
> +
> const __initconst struct hypervisor_x86 x86_hyper_kvm = {
> .name = "KVM",
> .detect = kvm_detect,
> .type = X86_HYPER_KVM,
> .init.guest_late_init = kvm_guest_init,
> .init.x2apic_available = kvm_para_available,
> + .init.init_platform = kvm_init_platform,
> };
>
> static __init int activate_jump_labels(void)
> diff --git a/include/uapi/linux/kvm_para.h b/include/uapi/linux/kvm_para.h
> index dcf629d..7395f38 100644
> --- a/include/uapi/linux/kvm_para.h
> +++ b/include/uapi/linux/kvm_para.h
> @@ -26,6 +26,7 @@
> #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
--
Vitaly
