On Thu, Dec 13, 2012 at 08:19:01AM +0000, Zhang, Yang Z wrote:
> Gleb Natapov wrote on 2012-12-13:
> > On Thu, Dec 13, 2012 at 08:03:06AM +0000, Zhang, Yang Z wrote:
> >> Gleb Natapov wrote on 2012-12-13:
> >>> On Thu, Dec 13, 2012 at 07:54:35AM +0000, Zhang, Yang Z wrote:
> >>>> Gleb Natapov wrote on 2012-12-13:
> >>>>> On Thu, Dec 13, 2012 at 03:29:39PM +0800, Yang Zhang wrote:
> >>>>>> From: Yang Zhang <[email protected]>
> >>>>>>
> >>>>>> Ack interrupt on vmexit is required by Posted Interrupt. With it,
> >>>>>> when external interrupt caused vmexit, the cpu will acknowledge the
> >>>>>> interrupt controller and save the interrupt's vector in vmcs. Only
> >>>>>> enable it when posted interrupt is enabled.
> >>>>>>
> >>>>>> There are several approaches to enable it. This patch uses a simply
> >>>>>> way: re-generate an interrupt via self ipi.
> >>>>>>
> >>>>>> Signed-off-by: Yang Zhang <[email protected]>
> >>>>>> ---
> >>>>>> arch/x86/kvm/vmx.c | 20 +++++++++++++++++---
> >>>>>> 1 files changed, 17 insertions(+), 3 deletions(-)
> >>>>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> >>>>>> index 8cd9eb7..6b6bd03 100644
> >>>>>> --- a/arch/x86/kvm/vmx.c
> >>>>>> +++ b/arch/x86/kvm/vmx.c
> >>>>>> @@ -2549,7 +2549,7 @@ static __init int setup_vmcs_config(struct
> >>>>> vmcs_config *vmcs_conf)
> >>>>>> #ifdef CONFIG_X86_64
> >>>>>> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE;
> >>>>>> #endif
> >>>>>> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT;
> >>>>>> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT |
> >>>>> VM_EXIT_ACK_INTR_ON_EXIT;
> >>>>>> if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS,
> >>>>>> &_vmexit_control) < 0) return
> >>>>>> -EIO; @@ -3913,6 +3913,7 @@
> >>>>>> static int vmx_vcpu_setup(struct vcpu_vmx *vmx) unsigned long a;
> >>>>>> #endif int i;
> >>>>>> + u32 vmexit_ctrl = vmcs_config.vmexit_ctrl;
> >>>>>>
> >>>>>> /* I/O */ vmcs_write64(IO_BITMAP_A,
> >>>>>> __pa(vmx_io_bitmap_a)); @@
> >>>>>> -3996,8 +3997,10 @@ static int vmx_vcpu_setup(struct vcpu_vmx
> >>>>>> *vmx) vmx->guest_msrs[j].mask = -1ull;
> >>>>>> ++vmx->nmsrs; }
> >>>>>> -
> >>>>>> - vmcs_write32(VM_EXIT_CONTROLS, vmcs_config.vmexit_ctrl);
> >>>>>> +
> >>>>>> + if(!enable_apicv_pi)
> >>>>>> + vmexit_ctrl &= ~VM_EXIT_ACK_INTR_ON_EXIT;
> >>>>>> + vmcs_write32(VM_EXIT_CONTROLS, vmexit_ctrl);
> >>>>>>
> >>>>>> /* 22.2.1, 20.8.1 */
> >>>>>> vmcs_write32(VM_ENTRY_CONTROLS, vmcs_config.vmentry_ctrl);
> >>>>>> @@ -6267,6 +6270,17 @@ static void vmx_complete_atomic_exit(struct
> >>>>> vcpu_vmx *vmx)
> >>>>>> asm("int $2");
> >>>>>> kvm_after_handle_nmi(&vmx->vcpu);
> >>>>>> }
> >>>>>> + if ((exit_intr_info & INTR_INFO_INTR_TYPE_MASK) ==
> >>>>>> INTR_TYPE_EXT_INTR && + (exit_intr_info &
> >>>>>> INTR_INFO_VALID_MASK)
> >>>>>> && enable_apicv_pi) { + unsigned int vector, tmr; + +
> >>>>>> vector =
> >>>>>> exit_intr_info & INTR_INFO_VECTOR_MASK; + tmr =
> >>>>>> apic_read(APIC_TMR
> >>>>>> + ((vector &
> >>> ~0x1f)
> >>>>>>>> 1)); + apic_eoi(); + if ( !((1 << (vector %
> >>>>>>>> 32)) & tmr) )
> >>>>>> + apic->send_IPI_self(vector); + }
> >>>>> What happen with the idea to dispatch interrupt through idt without IPI?
> >>>> I am not sure upstream guys will allow to export idt to a module. If it
> >>>> is not a problem, then can do it as you suggested.
> >>>>
> >>> I replied to that before. No need to export idt to modules. Add function
> >>> to entry_32/64.S that does dispatching and export it instead.
> >> It still need to touch common code. Do you think upstream guys will
> >> buy-in this?
> >>
> > What's the problem with touching common code? Show the code, get the
> > acks. But wait for merge window to close.
> You are right. We hope to push the PI patch ASAP. If touch common code, it
> may need long time to discuss to get final decision.
> As we discussion early, I will enable this feature in kvm not just when PI is
> enabled later. At that time, we can get some performance data and to see
> whether self ipi has big problem. Before the data ready, I think to limit all
> changes inside KVM modules should be a better way. How do you think?
>
I think we have plenty of time till 3.9. We should do it right, not
quick.
--
Gleb.
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