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From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Tim Shearer" <tshearer@advaoptical.com>,
	"Liran Alon" <liran.alon@oracle.com>
Subject: [PATCH 0/3] KVM: VMX: Allow to disable ioport intercept per-VM by userspace
Date: Mon, 16 Apr 2018 22:45:59 -0700	[thread overview]
Message-ID: <1523943962-25415-1-git-send-email-wanpengli@tencent.com> (raw)

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@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Tim Shearer <tshearer@advaoptical.com>
Cc: Liran Alon <liran.alon@oracle.com>

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

             reply	other threads:[~2018-04-17  5:46 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  5:45 Wanpeng Li [this message]
2018-04-17  5:46 ` [PATCH 1/3] KVM: VMX: Introduce per-VM I/O permission bitmaps Wanpeng Li
2018-05-11 15:39   ` Konrad Rzeszutek Wilk
2018-05-15 21:55     ` Jim Mattson
2018-04-17  5:46 ` [PATCH 2/3] KVM: X86: Allow userspace to disable ioport intercept Wanpeng Li
2018-05-11 15:42   ` Konrad Rzeszutek Wilk
2018-05-11 15:43     ` Konrad Rzeszutek Wilk
2018-05-15 21:56       ` Jim Mattson
2018-05-16  1:13         ` Wanpeng Li
2018-04-17  5:46 ` [PATCH 3/3] KVM: VMX: Allow I/O port 0x80 bypass when userspace prefer Wanpeng Li
2018-05-11 15:44   ` Konrad Rzeszutek Wilk
2018-05-15 21:57     ` Jim Mattson
2018-05-08  7:55 ` [PATCH 0/3] KVM: VMX: Allow to disable ioport intercept per-VM by userspace Wanpeng Li
2018-05-08 16:14   ` Paolo Bonzini
2018-05-11 15:40 ` Konrad Rzeszutek Wilk
2018-05-12  1:03   ` Wanpeng Li
2018-05-14 13:48     ` Tim Shearer

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