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Re: [Qemu-devel] INVLPG and IPI emulation in KVM
From: |
Avi Kivity |
Subject: |
Re: [Qemu-devel] INVLPG and IPI emulation in KVM |
Date: |
Sun, 13 Nov 2011 14:44:41 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20110930 Thunderbird/7.0.1 |
On 11/13/2011 02:27 PM, Xin Tong wrote:
> I am investigating how INVLPG is emulated in kvm.
You're on the wrong list.
> It turns out that it calls
>
> kvm_mmu_invlpg
> kvm_mmu_flush_tlb
> kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
>
> and the kvm_make_request set the vcpu->requests bit to high, when the
> guest os resumes, it handles the bit. I have 2 questions
>
>
> 1. How does the make_request mechanism work ?
See vcpu_enter_guest().
> how does the guest
> handle the requests ?
The guest never sees them, this is all internal to kvm.
> 2. INVLPG invalidates a tlb entry, it is typically used when the page
> table changes. However, an ipi is typically used to invalidate the tlb
> entries in other processor cores, However, i can not find the
> emulation code for IPI instruction.
There is no IPI instruction, see lapic.c:apic_send_ipi().
--
error compiling committee.c: too many arguments to function