linux-kernel - Re: [PATCH v3 01/34] KVM: x86: hyper-v: Resurrect dedicated KVM_REQ_HV_TLB

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Date:   Wed, 11 May 2022 14:18:31 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 01/34] KVM: x86: hyper-v: Resurrect dedicated
 KVM_REQ_HV_TLB_FLUSH flag

On Thu, 2022-04-14 at 15:19 +0200, Vitaly Kuznetsov wrote:
> In preparation to implementing fine-grained Hyper-V TLB flush and
> L2 TLB flush, resurrect dedicated KVM_REQ_HV_TLB_FLUSH request bit. As
> KVM_REQ_TLB_FLUSH_GUEST is a stronger operation, clear KVM_REQ_HV_TLB_FLUSH
> request in kvm_service_local_tlb_flush_requests() when
> KVM_REQ_TLB_FLUSH_GUEST was also requested.
> 
> No functional change intended.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---
>  arch/x86/include/asm/kvm_host.h | 2 ++
>  arch/x86/kvm/hyperv.c           | 4 ++--
>  arch/x86/kvm/x86.c              | 6 +++++-
>  3 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 2c20f715f009..1de3ad9308d8 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -105,6 +105,8 @@
>  	KVM_ARCH_REQ_FLAGS(30, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
>  #define KVM_REQ_MMU_FREE_OBSOLETE_ROOTS \
>  	KVM_ARCH_REQ_FLAGS(31, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
> +#define KVM_REQ_HV_TLB_FLUSH \
> +	KVM_ARCH_REQ_FLAGS(32, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
>  
>  #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 46f9dfb60469..b402ad059eb9 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -1876,11 +1876,11 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
>  	 * analyze it here, flush TLB regardless of the specified address space.
>  	 */
>  	if (all_cpus) {
> -		kvm_make_all_cpus_request(kvm, KVM_REQ_TLB_FLUSH_GUEST);
> +		kvm_make_all_cpus_request(kvm, KVM_REQ_HV_TLB_FLUSH);
>  	} else {
>  		sparse_set_to_vcpu_mask(kvm, sparse_banks, valid_bank_mask, vcpu_mask);
>  
> -		kvm_make_vcpus_request_mask(kvm, KVM_REQ_TLB_FLUSH_GUEST, vcpu_mask);
> +		kvm_make_vcpus_request_mask(kvm, KVM_REQ_HV_TLB_FLUSH, vcpu_mask);
>  	}
>  
>  ret_success:
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index ab336f7c82e4..f633cff8cd7f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3360,8 +3360,12 @@ void kvm_service_local_tlb_flush_requests(struct kvm_vcpu *vcpu)
>  	if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu))
>  		kvm_vcpu_flush_tlb_current(vcpu);
>  
> -	if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu))
> +	if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) {
>  		kvm_vcpu_flush_tlb_guest(vcpu);
> +		kvm_clear_request(KVM_REQ_HV_TLB_FLUSH, vcpu);
> +	} else if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) {
> +		kvm_vcpu_flush_tlb_guest(vcpu);
> +	}
>  }
>  EXPORT_SYMBOL_GPL(kvm_service_local_tlb_flush_requests);
>  

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>

Best regards,
	Maxim Levitsky