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

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