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SubjectRe: [PATCH v3 14/37] KVM: x86: Move "flush guest's TLB" logic to separate kvm_x86_ops hook
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On 25/03/20 11:23, Vitaly Kuznetsov wrote:
> What do you think about the following (very lightly
> tested)?
>
> commit 485b4a579605597b9897b3d9ec118e0f7f1138ad
> Author: Vitaly Kuznetsov <vkuznets@redhat.com>
> Date: Wed Mar 25 11:14:25 2020 +0100
>
> KVM: x86: make Hyper-V PV TLB flush use tlb_flush_guest()
>
> Hyper-V PV TLB flush mechanism does TLB flush on behalf of the guest
> so doing tlb_flush_all() is an overkill, switch to using tlb_flush_guest()
> (just like KVM PV TLB flush mechanism) instead. Introduce
> KVM_REQ_HV_TLB_FLUSH to support the change.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 167729624149..8c5659ed211b 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -84,6 +84,7 @@
> #define KVM_REQ_APICV_UPDATE \
> KVM_ARCH_REQ_FLAGS(25, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
> #define KVM_REQ_TLB_FLUSH_CURRENT KVM_ARCH_REQ(26)
> +#define KVM_REQ_HV_TLB_FLUSH KVM_ARCH_REQ(27)
>
> #define CR0_RESERVED_BITS \
> (~(unsigned long)(X86_CR0_PE | X86_CR0_MP | X86_CR0_EM | X86_CR0_TS \
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index a86fda7a1d03..0d051ed11f38 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -1425,8 +1425,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *current_vcpu, u64 ingpa,
> * vcpu->arch.cr3 may not be up-to-date for running vCPUs so we can't
> * analyze it here, flush TLB regardless of the specified address space.
> */
> - kvm_make_vcpus_request_mask(kvm,
> - KVM_REQ_TLB_FLUSH | KVM_REQUEST_NO_WAKEUP,
> + kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH,
> vcpu_mask, &hv_vcpu->tlb_flush);
>

Looks good, but why are you dropping KVM_REQUEST_NO_WAKEUP?

Paolo

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