linux-kernel - Re: [PATCH 0/3] KVM: VMX: Allow to disable ioport intercept per-VM by userspace

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Date:   Tue, 8 May 2018 15:55:37 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Tim Shearer <tshearer@...aoptical.com>,
        Liran Alon <liran.alon@...cle.com>
Subject: Re: [PATCH 0/3] KVM: VMX: Allow to disable ioport intercept per-VM by userspace

2018-04-17 13:45 GMT+08:00 Wanpeng Li <kernellwp@...il.com>:
> Tim Shearer reported that "There is a guest which is running a packet
> forwarding app based on the DPDK (dpdk.org). The packet receive routine
> writes to 0xc070 using glibc's "outw_p" function which does an additional
> write to I/O port 0x80. It does this write for every packet that's
> received, causing a flood of KVM userspace context switches". He uses
> mpstat to observe a CPU performing L2 packet forwarding on a pinned
> guest vCPU, the guest time is 95 percent when allowing I/O port 0x80
> bypass, however, it is 65.78 percent when I/O port 0x80 bypss is
> disabled.
>
> This patchset introduces per-VM I/O permission bitmaps, the userspace
> can disable the ioport intercept when they are more concern the
> performance than the security.
>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: Radim Krčmář <rkrcmar@...hat.com>
> Cc: Tim Shearer <tshearer@...aoptical.com>
> Cc: Liran Alon <liran.alon@...cle.com>
>

Hi Paolo,

Did you send the patch to glibc or the patchset still can be considered?

Regards,
Wanpeng Li

> Wanpeng Li (3):
>   KVM: VMX: Introduce per-VM I/O permission bitmaps
>   KVM: X86: Allow userspace to disable ioport intercept
>   KVM: VMX: Allow I/O port 0x80 bypass when userspace prefer
>
>  Documentation/virtual/kvm/api.txt | 11 +++++++++++
>  arch/x86/include/asm/kvm_host.h   |  2 ++
>  arch/x86/kvm/vmx.c                | 41 ++++++++++++++++++++++++++++++++++++---
>  arch/x86/kvm/x86.c                |  5 +++++
>  include/uapi/linux/kvm.h          |  1 +
>  5 files changed, 57 insertions(+), 3 deletions(-)
>
> --
> 2.7.4
>