On Wed, Jan 30, 2013 at 09:03:11PM -0200, Marcelo Tosatti wrote:
> On Fri, Jan 25, 2013 at 12:40:21AM +0000, Zhang, Yang Z wrote:
> > Marcelo Tosatti wrote on 2013-01-25:
> > > On Thu, Dec 13, 2012 at 03:29:40PM +0800, Yang Zhang wrote:
> > >> From: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> > >>
> > >> Posted Interrupt allows APIC interrupts to inject into guest directly
> > >> without any vmexit.
> > >>
> > >> - When delivering a interrupt to guest, if target vcpu is running,
> > >> update Posted-interrupt requests bitmap and send a notification event
> > >> to the vcpu. Then the vcpu will handle this interrupt automatically,
> > >> without any software involvemnt.
> > >> - If target vcpu is not running or there already a notification event
> > >> pending in the vcpu, do nothing. The interrupt will be handled by
> > >> next vm entry.
> > >> Signed-off-by: Yang Zhang <yang.z.zhang@xxxxxxxxx>
> > >> ---
> > >> arch/x86/include/asm/entry_arch.h | 1 +
> > >> arch/x86/include/asm/hw_irq.h | 1 + arch/x86/include/asm/irq.h
> > >> | 1 + arch/x86/include/asm/irq_vectors.h | 4 +
> > >> arch/x86/include/asm/kvm_host.h | 3 + arch/x86/include/asm/vmx.h
> > >> | 4 + arch/x86/kernel/entry_64.S | 2 +
> > >> arch/x86/kernel/irq.c | 25 +++++++
> > >> arch/x86/kernel/irqinit.c | 2 + arch/x86/kvm/lapic.c
> > >> | 16 +++- arch/x86/kvm/lapic.h | 1 +
> > >> arch/x86/kvm/vmx.c | 133
> > >> +++++++++++++++++++++++++++++++++--- 12 files changed, 180
> > >> insertions(+), 13 deletions(-)
> > >> diff --git a/arch/x86/include/asm/entry_arch.h
> > >> b/arch/x86/include/asm/entry_arch.h index 40afa00..7b0a29e 100644 ---
> > >> a/arch/x86/include/asm/entry_arch.h +++
> > >> b/arch/x86/include/asm/entry_arch.h @@ -18,6 +18,7 @@
> > >> BUILD_INTERRUPT(reboot_interrupt,REBOOT_VECTOR)
> > >> #endif
> > >>
> > >> BUILD_INTERRUPT(x86_platform_ipi, X86_PLATFORM_IPI_VECTOR)
> > >> +BUILD_INTERRUPT(posted_intr_ipi, POSTED_INTR_VECTOR)
> > >>
> > >> /*
> > >> * every pentium local APIC has two 'local interrupts', with a
> > >> diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
> > >> index eb92a6e..ee61af3 100644
> > >> --- a/arch/x86/include/asm/hw_irq.h
> > >> +++ b/arch/x86/include/asm/hw_irq.h
> > >> @@ -28,6 +28,7 @@
> > >> /* Interrupt handlers registered during init_IRQ */ extern void
> > >> apic_timer_interrupt(void); extern void x86_platform_ipi(void);
> > >> +extern void posted_intr_ipi(void); extern void error_interrupt(void);
> > >> extern void irq_work_interrupt(void);
> > >> diff --git a/arch/x86/include/asm/irq.h b/arch/x86/include/asm/irq.h
> > >> index ba870bb..cff9933 100644
> > >> --- a/arch/x86/include/asm/irq.h
> > >> +++ b/arch/x86/include/asm/irq.h
> > >> @@ -30,6 +30,7 @@ extern void irq_force_complete_move(int);
> > >> #endif
> > >>
> > >> extern void (*x86_platform_ipi_callback)(void); +extern void
> > >> (*posted_intr_callback)(void); extern void native_init_IRQ(void);
> > >> extern bool handle_irq(unsigned irq, struct pt_regs *regs);
> > >> diff --git a/arch/x86/include/asm/irq_vectors.h
> > >> b/arch/x86/include/asm/irq_vectors.h index 1508e51..8f2e383 100644 ---
> > >> a/arch/x86/include/asm/irq_vectors.h +++
> > >> b/arch/x86/include/asm/irq_vectors.h @@ -102,6 +102,10 @@
> > >> */
> > >> #define X86_PLATFORM_IPI_VECTOR 0xf7
> > >> +#ifdef CONFIG_HAVE_KVM
> > >> +#define POSTED_INTR_VECTOR 0xf2
> > >> +#endif
> > >> +
> > >> /*
> > >> * IRQ work vector:
> > >> */
> > >> diff --git a/arch/x86/include/asm/kvm_host.h
> > >> b/arch/x86/include/asm/kvm_host.h index 7e26d1a..82423a8 100644 ---
> > >> a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h
> > >> @@ -700,6 +700,9 @@ struct kvm_x86_ops {
> > >> int (*has_virtual_interrupt_delivery)(struct kvm_vcpu *vcpu);
> > >> void (*update_irq)(struct kvm_vcpu *vcpu);
> > >> void (*update_eoi_exitmap)(struct kvm_vcpu *vcpu, int vector, bool set);
> > >> + int (*has_posted_interrupt)(struct kvm_vcpu *vcpu);
> > >> + int (*send_nv)(struct kvm_vcpu *vcpu, int vector);
> > >> + void (*update_irr)(struct kvm_vcpu *vcpu);
> > >> int (*set_tss_addr)(struct kvm *kvm, unsigned int addr);
> > >> int (*get_tdp_level)(void);
> > >> u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
> > >> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> > >> index 1003341..7b9e1d0 100644
> > >> --- a/arch/x86/include/asm/vmx.h
> > >> +++ b/arch/x86/include/asm/vmx.h
> > >> @@ -152,6 +152,7 @@
> > >> #define PIN_BASED_EXT_INTR_MASK 0x00000001
> > >> #define PIN_BASED_NMI_EXITING 0x00000008
> > >> #define PIN_BASED_VIRTUAL_NMIS 0x00000020
> > >> +#define PIN_BASED_POSTED_INTR 0x00000080
> > >>
> > >> #define VM_EXIT_SAVE_DEBUG_CONTROLS 0x00000002 #define
> > >> VM_EXIT_HOST_ADDR_SPACE_SIZE 0x00000200 @@ -174,6 +175,7 @@
> > >> /* VMCS Encodings */ enum vmcs_field { VIRTUAL_PROCESSOR_ID
> > >> = 0x00000000, + POSTED_INTR_NV = 0x00000002,
> > >> GUEST_ES_SELECTOR = 0x00000800, GUEST_CS_SELECTOR
> > >> = 0x00000802, GUEST_SS_SELECTOR = 0x00000804,
> > >> @@ -208,6 +210,8 @@ enum vmcs_field { VIRTUAL_APIC_PAGE_ADDR_HIGH
> > >> = 0x00002013, APIC_ACCESS_ADDR = 0x00002014,
> > >> APIC_ACCESS_ADDR_HIGH = 0x00002015,
> > >> + POSTED_INTR_DESC_ADDR = 0x00002016,
> > >> + POSTED_INTR_DESC_ADDR_HIGH = 0x00002017,
> > >> EPT_POINTER = 0x0000201a,
> > >> EPT_POINTER_HIGH = 0x0000201b,
> > >> EOI_EXIT_BITMAP0 = 0x0000201c,
> > >> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> > >> index b51b2c7..d06eea1 100644
> > >> --- a/arch/x86/kernel/entry_64.S
> > >> +++ b/arch/x86/kernel/entry_64.S
> > >> @@ -1160,6 +1160,8 @@ apicinterrupt LOCAL_TIMER_VECTOR \
> > >> apic_timer_interrupt smp_apic_timer_interrupt
> > >> apicinterrupt X86_PLATFORM_IPI_VECTOR \
> > >> x86_platform_ipi smp_x86_platform_ipi
> > >> +apicinterrupt POSTED_INTR_VECTOR \
> > >> + posted_intr_ipi smp_posted_intr_ipi
> > >>
> > >> apicinterrupt THRESHOLD_APIC_VECTOR \
> > >> threshold_interrupt smp_threshold_interrupt
> > >> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
> > >> index e4595f1..781d324 100644
> > >> --- a/arch/x86/kernel/irq.c
> > >> +++ b/arch/x86/kernel/irq.c
> > >> @@ -22,6 +22,9 @@ atomic_t irq_err_count;
> > >>
> > >> /* Function pointer for generic interrupt vector handling */
> > >> void (*x86_platform_ipi_callback)(void) = NULL;
> > >> +/* Function pointer for posted interrupt vector handling */
> > >> +void (*posted_intr_callback)(void) = NULL;
> > >> +EXPORT_SYMBOL_GPL(posted_intr_callback);
> > >>
> > >> /*
> > >> * 'what should we do if we get a hw irq event on an illegal vector'.
> > >> @@ -228,6 +231,28 @@ void smp_x86_platform_ipi(struct pt_regs *regs)
> > >> set_irq_regs(old_regs);
> > >> }
> > >> +/*
> > >> + * Handler for POSTED_INTERRUPT_VECTOR.
> > >> + */
> > >> +void smp_posted_intr_ipi(struct pt_regs *regs)
> > >> +{
> > >> + struct pt_regs *old_regs = set_irq_regs(regs);
> > >> +
> > >> + ack_APIC_irq();
> > >> +
> > >> + irq_enter();
> > >> +
> > >> + exit_idle();
> > >> +
> > >> + if (posted_intr_callback)
> > >> + posted_intr_callback();
> > >> +
> > >> + irq_exit();
> > >> +
> > >> + set_irq_regs(old_regs);
> > >> +}
> > >> +
> > >> +
> > >> EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);
> > >>
> > >> #ifdef CONFIG_HOTPLUG_CPU
> > >> diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
> > >> index 6e03b0d..d15ca4f 100644
> > >> --- a/arch/x86/kernel/irqinit.c
> > >> +++ b/arch/x86/kernel/irqinit.c
> > >> @@ -205,6 +205,8 @@ static void __init apic_intr_init(void)
> > >>
> > >> /* IPI for X86 platform specific use */
> > >> alloc_intr_gate(X86_PLATFORM_IPI_VECTOR, x86_platform_ipi);
> > >> + /* IPI for posted interrupt use */
> > >> + alloc_intr_gate(POSTED_INTR_VECTOR, posted_intr_ipi);
> > >>
> > >> /* IPI vectors for APIC spurious and error interrupts */
> > >> alloc_intr_gate(SPURIOUS_APIC_VECTOR, spurious_interrupt);
> > >> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> > >> index 2109a6a..d660b9d 100644
> > >> --- a/arch/x86/kvm/lapic.c
> > >> +++ b/arch/x86/kvm/lapic.c
> > >> @@ -350,6 +350,7 @@ static inline int apic_find_highest_irr(struct kvm_lapic
> > > *apic)
> > >> if (!apic->irr_pending)
> > >> return -1;
> > >> + kvm_x86_ops->update_irr(apic->vcpu);
> > >> result = apic_search_irr(apic);
> > >> ASSERT(result == -1 || result >= 16);
> > >> @@ -725,18 +726,25 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int
> > > delivery_mode,
> > >> if (trig_mode) {
> > >> apic_debug("level trig mode for vector %d", vector);
> > >> apic_set_vector(vector, apic->regs + APIC_TMR);
> > >> - } else
> > >> + } else {
> > >> apic_clear_vector(vector, apic->regs + APIC_TMR);
> > >> -
> > >> + if (kvm_x86_ops->has_posted_interrupt(vcpu)) {
> > >> + result = 1;
> > >> + apic->irr_pending = true;
> > >> + kvm_x86_ops->send_nv(vcpu, vector);
> > >> + goto out;
> > >> + }
> > >
> > > Hi,
> > >
> > > Steps 4, 5 and 6 of section 29.6 are executed in both VMX root/non-root
> > > modes, or only non-root mode?
> > SDM doesn't tell. But we don't need know this in software level.
> >
> > >
> > >
> > > If only non-root mode, there is a problem if target vcpu<->pcpu vm-exits
> > > before receiving and acking the interrupt. In that case PIR set bits are
> > > not transferred to VIRR.
> > >
> > > It would be necessary to read notification bit on VM-exit and, if set,
> > > do PIR->VIRR transfer in software. The downside, is lack of an atomic
> > In current implementation, it will sync PIR to VIRR before vmentry.
> >
> > > (VIRR |= PIR; PIR = 0) in software. So it would require synchronization
> > > to KVM APIC injection (which ATM relies on atomic test_and_set of IRR).
>
> Some comments:
>
> Enable ack-on-exit feature patch:
> 1) Value of register VM_EXIT_INTR_INFO is available at
> vmx->exit_intr_info. See commit
> 887864758580c80710947c38a4692032163777df.
>
> Posted interrupt patch:
> 2) Must move IN_GUEST_MODE assignment after local_irq_disable, in
> vcpu_enter_guest function. Otherwise:
>
> cpu0 vcpu1<->cpu1
>
> vcpu->mode = IN_GUEST_MODE
>
> if IN_GUEST_MODE == true
> send IPI
> local_irq_disable
>
> PIR not transferred to VIRR, misses interrupt.
>
> 3) Must check outstanding PIR notification bit unconditionally on
> every VM-entry, because:
>
> 1. local_irq_disable
> 2. vcpu->mode = IN_GUEST_MODE
> 3. vmenter
> 4. vmexit
> 5. vcpu->mode = OUTSIDE_GUEST_MODE
>
> If PIR-IPI-interrupt is sent between an event which triggers VM-exit
> (for example, an external interrupt due to a device), and step 5
> (assignment of vcpu->mode), the PIR->VIRR transfer before vmentry must
> be made.
Check for outstanding PIR notification bit must be made after disabling
local interrupts, in vcpu_enter_guest. If PIR notification bit is
set, should set KVM_REQ_EVENT in vcpu->requests, so that ->run is not
executed, and vcpu_enter_guest reexecuted.
Then the PIR->VIRR SW transfer can be made in KVM_REQ_EVENT processing
(in a separate function please, not from get_interrupt).
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