On 28/07/2015 01:17, Steve Rutherford wrote:
> First patch in a series which enables the relocation of the
> PIC/IOAPIC to userspace.
>
> Adds capability KVM_CAP_SPLIT_IRQCHIP;
>
> KVM_CAP_SPLIT_IRQCHIP enables the construction of LAPICs without the
> rest of the irqchip.
>
> Compile tested for x86.
>
> Signed-off-by: Steve Rutherford <[email protected]>
> Suggested-by: Andrew Honig <[email protected]>
> ---
> Documentation/virtual/kvm/api.txt | 15 +++++++++++++++
> arch/powerpc/kvm/irq.h | 1 -
> arch/s390/kvm/irq.h | 1 -
> arch/x86/include/asm/kvm_host.h | 2 ++
> arch/x86/kvm/i8254.c | 5 ++++-
> arch/x86/kvm/ioapic.h | 9 +++++++++
> arch/x86/kvm/irq.h | 6 ++++++
> arch/x86/kvm/irq_comm.c | 9 ++++++++-
> arch/x86/kvm/lapic.c | 9 ++++++---
> arch/x86/kvm/vmx.c | 4 ++--
> arch/x86/kvm/x86.c | 23 +++++++++++++++++++++--
> include/kvm/arm_vgic.h | 1 +
> include/linux/kvm_host.h | 1 +
> include/uapi/linux/kvm.h | 1 +
> 14 files changed, 76 insertions(+), 11 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt
> b/Documentation/virtual/kvm/api.txt
> index a4ebcb7..b655024 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -3620,6 +3620,21 @@ struct {
>
> KVM handlers should exit to userspace with rc = -EREMOTE.
>
> +7.5 KVM_SPLIT_IRQCHIP
> +
> +Architectures: x86
> +Parameters: None
> +Returns: 0 on success, -1 on error
> +
> +Create a local apic for each processor in the kernel. With this capability
> +enabled, the userspace VMM is expected to emulate the IOAPIC and PIC.
> +
> +This supersedes KVM_CREATE_IRQCHIP, creating only local APICs, but no in
> kernel
> +IOAPIC or PIC. This also enables in kernel routing of interrupt requests.
> +
> +Fails if VCPU has already been created, or if the irqchip is already in the
> +kernel (i.e. KVM_CREATE_IRQCHIP has already been called).
> +
>
> 8. Other capabilities.
> ----------------------
> diff --git a/arch/powerpc/kvm/irq.h b/arch/powerpc/kvm/irq.h
> index 5a9a10b..772fa8c 100644
> --- a/arch/powerpc/kvm/irq.h
> +++ b/arch/powerpc/kvm/irq.h
> @@ -16,5 +16,4 @@ static inline int irqchip_in_kernel(struct kvm *kvm)
> smp_rmb();
> return ret;
> }
> -
> #endif
> diff --git a/arch/s390/kvm/irq.h b/arch/s390/kvm/irq.h
> index d98e415..9a21a86 100644
> --- a/arch/s390/kvm/irq.h
> +++ b/arch/s390/kvm/irq.h
> @@ -18,5 +18,4 @@ static inline int irqchip_in_kernel(struct kvm *kvm)
> {
> return 1;
> }
> -
> #endif
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index fa32b53..18a110b 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -669,6 +669,8 @@ struct kvm_arch {
> bool boot_vcpu_runs_old_kvmclock;
>
> u64 disabled_quirks;
> +
> + bool irqchip_split;
> };
>
> struct kvm_vm_stat {
> diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
> index f90952f..5708850 100644
> --- a/arch/x86/kvm/i8254.c
> +++ b/arch/x86/kvm/i8254.c
> @@ -35,6 +35,7 @@
> #include <linux/kvm_host.h>
> #include <linux/slab.h>
>
> +#include "ioapic.h"
> #include "irq.h"
> #include "i8254.h"
> #include "x86.h"
> @@ -333,7 +334,9 @@ static void create_pit_timer(struct kvm *kvm, u32 val,
> int is_period)
> struct kvm_kpit_state *ps = &kvm->arch.vpit->pit_state;
> s64 interval;
>
> - if (!irqchip_in_kernel(kvm) || ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
> + if (!irqchip_in_kernel(kvm) ||
> + !ioapic_in_kernel(kvm) ||
Here the irqchip_in_kernel check is unnecessary.
> + ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)
> return;
>
> interval = muldiv64(val, NSEC_PER_SEC, KVM_PIT_FREQ);
> diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
> index ca0b0b4..d8cc54b 100644
> --- a/arch/x86/kvm/ioapic.h
> +++ b/arch/x86/kvm/ioapic.h
> @@ -98,6 +98,15 @@ static inline struct kvm_ioapic *ioapic_irqchip(struct kvm
> *kvm)
> return kvm->arch.vioapic;
> }
>
> +static inline int ioapic_in_kernel(struct kvm *kvm)
> +{
> + int ret;
> +
> + ret = (ioapic_irqchip(kvm) != NULL);
> + smp_rmb();
> + return ret;
> +}
> +
> static inline bool kvm_ioapic_handles_vector(struct kvm *kvm, int vector)
> {
> struct kvm_ioapic *ioapic = kvm->arch.vioapic;
> diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
> index ad68c73..2f13dd5 100644
> --- a/arch/x86/kvm/irq.h
> +++ b/arch/x86/kvm/irq.h
> @@ -83,11 +83,17 @@ static inline struct kvm_pic *pic_irqchip(struct kvm *kvm)
> return kvm->arch.vpic;
> }
>
> +static inline int irqchip_split(struct kvm *kvm)
> +{
> + return kvm->arch.irqchip_split;
> +}
> +
> static inline int irqchip_in_kernel(struct kvm *kvm)
> {
> int ret;
>
> ret = (pic_irqchip(kvm) != NULL);
> + ret |= irqchip_split(kvm);
> smp_rmb();
> return ret;
> }
> diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
> index 9efff9e..67f6b62 100644
> --- a/arch/x86/kvm/irq_comm.c
> +++ b/arch/x86/kvm/irq_comm.c
> @@ -208,7 +208,7 @@ void kvm_free_irq_source_id(struct kvm *kvm, int
> irq_source_id)
> goto unlock;
> }
> clear_bit(irq_source_id, &kvm->arch.irq_sources_bitmap);
> - if (!irqchip_in_kernel(kvm))
> + if (!ioapic_in_kernel(kvm))
> goto unlock;
>
> kvm_ioapic_clear_all(kvm->arch.vioapic, irq_source_id);
> @@ -328,3 +328,10 @@ int kvm_setup_default_irq_routing(struct kvm *kvm)
> return kvm_set_irq_routing(kvm, default_routing,
> ARRAY_SIZE(default_routing), 0);
> }
> +
> +static const struct kvm_irq_routing_entry empty_routing[] = {};
> +
> +int kvm_setup_empty_irq_routing(struct kvm *kvm)
> +{
> + return kvm_set_irq_routing(kvm, empty_routing, 0, 0);
> +}
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 2a5ca97..536b79e 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -209,7 +209,8 @@ out:
> if (old)
> kfree_rcu(old, rcu);
>
> - kvm_vcpu_request_scan_ioapic(kvm);
> + if (!irqchip_split(kvm))
Here please check ioapic_in_kernel.
> + kvm_vcpu_request_scan_ioapic(kvm);
> }
>
> static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
> @@ -1838,7 +1839,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
> kvm_x86_ops->hwapic_isr_update(vcpu->kvm,
> apic_find_highest_isr(apic));
> kvm_make_request(KVM_REQ_EVENT, vcpu);
> - kvm_rtc_eoi_tracking_restore_one(vcpu);
> + if (!irqchip_split(vcpu->kvm))
Here please check ioapic_in_kernel.
> + kvm_rtc_eoi_tracking_restore_one(vcpu);
> }
>
> void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
> @@ -1921,7 +1923,8 @@ static void apic_sync_pv_eoi_to_guest(struct kvm_vcpu
> *vcpu,
> /* Cache not set: could be safe but we don't bother. */
> apic->highest_isr_cache == -1 ||
> /* Need EOI to update ioapic. */
> - kvm_ioapic_handles_vector(vcpu->kvm, apic->highest_isr_cache)) {
> + kvm_ioapic_handles_vector(vcpu->kvm, apic->highest_isr_cache) ||
> + irqchip_split(vcpu->kvm)) {
This is ugly (and if anything irqchip_split should be done before
kvm_ioapic_handles_vector). Could this just test the EOI exit bitmap
instead?
Also, who sets TMR in the split irqchip case? I'll post a patch roday
or tomorrow to compute TMR in __apic_accept_irq and to do the
aforementioned EOI exit bitmap test.
> /*
> * PV EOI was disabled by apic_sync_pv_eoi_from_guest
> * so we need not do anything here.
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 4014a82..08203a1 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -948,7 +948,7 @@ static inline bool cpu_has_vmx_tpr_shadow(void)
>
> static inline bool vm_need_tpr_shadow(struct kvm *kvm)
> {
> - return (cpu_has_vmx_tpr_shadow()) && (irqchip_in_kernel(kvm));
> + return (cpu_has_vmx_tpr_shadow()) && irqchip_in_kernel(kvm);
> }
>
> static inline bool cpu_has_secondary_exec_ctrls(void)
> @@ -9485,7 +9485,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu,
> struct vmcs12 *vmcs12)
> /* vmcs12's VM_ENTRY_LOAD_IA32_EFER and VM_ENTRY_IA32E_MODE are
> * emulated by vmx_set_efer(), below.
> */
> - vm_entry_controls_init(vmx,
> + vm_entry_controls_init(vmx,
> (vmcs12->vm_entry_controls & ~VM_ENTRY_LOAD_IA32_EFER &
> ~VM_ENTRY_IA32E_MODE) |
> (vmcs_config.vmentry_ctrl & ~VM_ENTRY_IA32E_MODE));
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 28076c2..6d4b4dc 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2461,6 +2461,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long
> ext)
> case KVM_CAP_TSC_DEADLINE_TIMER:
> case KVM_CAP_ENABLE_CAP_VM:
> case KVM_CAP_DISABLE_QUIRKS:
> + case KVM_CAP_SPLIT_IRQCHIP:
> #ifdef CONFIG_KVM_DEVICE_ASSIGNMENT
> case KVM_CAP_ASSIGN_DEV_IRQ:
> case KVM_CAP_PCI_2_3:
> @@ -3568,6 +3569,23 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
> kvm->arch.disabled_quirks = cap->args[0];
> r = 0;
> break;
> + case KVM_CAP_SPLIT_IRQCHIP: {
> + mutex_lock(&kvm->lock);
> + r = -EEXIST;
> + if (irqchip_in_kernel(kvm))
> + goto split_irqchip_unlock;
> + r = -EINVAL;
> + if (atomic_read(&kvm->online_vcpus))
> + goto split_irqchip_unlock;
> + r = kvm_setup_empty_irq_routing(kvm);
> + if (r)
> + goto split_irqchip_unlock;
Need a smp_wmb() here, pairing with irqchip_in_kernel.
Paolo
> + kvm->arch.irqchip_split = true;
> + r = 0;
> +split_irqchip_unlock:
> + mutex_unlock(&kvm->lock);
> + break;
> + }
> default:
> r = -EINVAL;
> break;
> @@ -3686,7 +3704,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
> }
>
> r = -ENXIO;
> - if (!irqchip_in_kernel(kvm))
> + if (!irqchip_in_kernel(kvm) || !ioapic_in_kernel(kvm))
> goto get_irqchip_out;
> r = kvm_vm_ioctl_get_irqchip(kvm, chip);
> if (r)
> @@ -3710,7 +3728,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
> }
>
> r = -ENXIO;
> - if (!irqchip_in_kernel(kvm))
> + if (!irqchip_in_kernel(kvm) || !ioapic_in_kernel(kvm))
> goto set_irqchip_out;
> r = kvm_vm_ioctl_set_irqchip(kvm, chip);
> if (r)
> @@ -3836,6 +3854,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
> r = kvm_vm_ioctl_enable_cap(kvm, &cap);
> break;
> }
> +
> default:
> r = kvm_vm_ioctl_assigned_device(kvm, ioctl, arg);
> }
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 133ea00..ffe1f4e 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -329,6 +329,7 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
> int kvm_vgic_vcpu_active_irq(struct kvm_vcpu *vcpu);
>
> #define irqchip_in_kernel(k) (!!((k)->arch.vgic.in_kernel))
> +#define lapic_in_kernel(k) (irqchip_in_kernel(k))
> #define vgic_initialized(k) (!!((k)->arch.vgic.nr_cpus))
> #define vgic_ready(k) ((k)->arch.vgic.ready)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 51103f0..f7eab09 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1000,6 +1000,7 @@ static inline int mmu_notifier_retry(struct kvm *kvm,
> unsigned long mmu_seq)
> #endif
>
> int kvm_setup_default_irq_routing(struct kvm *kvm);
> +int kvm_setup_empty_irq_routing(struct kvm *kvm);
> int kvm_set_irq_routing(struct kvm *kvm,
> const struct kvm_irq_routing_entry *entries,
> unsigned nr,
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 9ef19eb..e4304d0 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -818,6 +818,7 @@ struct kvm_ppc_smmu_info {
> #define KVM_CAP_DISABLE_QUIRKS 116
> #define KVM_CAP_X86_SMM 117
> #define KVM_CAP_MULTI_ADDRESS_SPACE 118
> +#define KVM_CAP_SPLIT_IRQCHIP 119
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
>
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