linux-kernel - Re: [PATCH v8 1/4] KVM: X86: Add vCPU running/preempted state

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3fb56993-3bb6-442c-f12e-0c99c06ef5c2@redhat.com>
Date:   Wed, 13 Dec 2017 11:20:32 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Wanpeng Li <kernellwp@...il.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH v8 1/4] KVM: X86: Add vCPU running/preempted state

On 13.12.2017 02:33, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@...mail.com>
> 
> This patch reuses the preempted field in kvm_steal_time, and will export
> the vcpu running/pre-empted information to the guest from host. This will
> enable guest to intelligently send ipi to running vcpus and set flag for
> pre-empted vcpus. This will prevent waiting for vcpus that are not running.
> 
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Radim Krčmář <rkrcmar@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
> ---
>  arch/x86/include/uapi/asm/kvm_para.h | 3 +++
>  arch/x86/kernel/kvm.c                | 2 +-
>  arch/x86/kvm/x86.c                   | 4 ++--
>  3 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
> index 09cc064..763b692 100644
> --- a/arch/x86/include/uapi/asm/kvm_para.h
> +++ b/arch/x86/include/uapi/asm/kvm_para.h
> @@ -51,6 +51,9 @@ struct kvm_steal_time {
>  	__u32 pad[11];
>  };
>  
> +#define KVM_VCPU_NOT_PREEMPTED      (0 << 0)
> +#define KVM_VCPU_PREEMPTED          (1 << 0)

Is it really helpful to have two flags?

Just use KVM_VCPU_PREEMPTED  and clear that one in record_steal_time()


-- 

Thanks,

David / dhildenb