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Message-ID: <564022A1.2040003@redhat.com> Date: Mon, 9 Nov 2015 12:35:45 +0800 From: Jason Wang <jasowang@...hat.com> To: "Michael S. Tsirkin" <mst@...hat.com> Cc: gleb@...nel.org, pbonzini@...hat.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org, cornelia.huck@...ibm.com Subject: Re: [PATCH V6 0/6] Fast mmio eventfd fixes On 11/09/2015 01:11 AM, Michael S. Tsirkin wrote: > On Tue, Sep 15, 2015 at 02:41:53PM +0800, Jason Wang wrote: >> Hi: >> >> This series fixes two issues of fast mmio eventfd: >> >> 1) A single iodev instance were registerd on two buses: KVM_MMIO_BUS >> and KVM_FAST_MMIO_BUS. This will cause double in >> ioeventfd_destructor() >> 2) A zero length iodev on KVM_MMIO_BUS will never be found but >> kvm_io_bus_cmp(). This will lead e.g the eventfd will be trapped by >> qemu instead of host. >> >> 1 is fixed by allocating two instances of iodev and introduce a new >> capability for userspace. 2 is fixed by ignore the actual length if >> the length of iodev is zero in kvm_io_bus_cmp(). >> >> Please review. >> Changes from V5: >> - move patch of explicitly checking for KVM_MMIO_BUS to patch 1 and >> remove the unnecessary checks >> - even more grammar and typo fixes >> - rabase to kvm.git >> - document KVM_CAP_FAST_MMIO > What's up with userspace using this capability? It was renamed to KVM_CAP_IOEVENTFD_ANY_LENGTH. > Did patches ever get posted? See https://lkml.org/lkml/2015/9/28/208 > >> Changes from V4: >> - move the location of kvm_assign_ioeventfd() in patch 1 which reduce >> the change set. >> - commit log typo fixes >> - switch to use kvm_deassign_ioeventfd_id) when fail to register to >> fast mmio bus >> - change kvm_io_bus_cmp() as Paolo's suggestions >> - introduce a new capability to avoid new userspace crash old kernel >> - add a new patch that only try to register mmio eventfd on fast mmio >> bus >> >> Changes from V3: >> >> - Don't do search on two buses when trying to do write on >> KVM_MMIO_BUS. This fixes a small regression found by vmexit.flat. >> - Since we don't do search on two buses, change kvm_io_bus_cmp() to >> let it can find zero length iodevs. >> - Fix the unnecessary lines in tracepoint patch. >> >> Changes from V2: >> - Tweak styles and comment suggested by Cornelia. >> >> Changes from v1: >> - change ioeventfd_bus_from_flags() to return KVM_FAST_MMIO_BUS when >> needed to save lots of unnecessary changes. >> >> Jason Wang (6): >> kvm: don't try to register to KVM_FAST_MMIO_BUS for non mmio eventfd >> kvm: factor out core eventfd assign/deassign logic >> kvm: fix double free for fast mmio eventfd >> kvm: fix zero length mmio searching >> kvm: add tracepoint for fast mmio >> kvm: add fast mmio capabilitiy >> >> Documentation/virtual/kvm/api.txt | 7 ++- >> arch/x86/kvm/trace.h | 18 ++++++ >> arch/x86/kvm/vmx.c | 1 + >> arch/x86/kvm/x86.c | 1 + >> include/uapi/linux/kvm.h | 1 + >> virt/kvm/eventfd.c | 124 ++++++++++++++++++++++---------------- >> virt/kvm/kvm_main.c | 20 +++++- >> 7 files changed, 118 insertions(+), 54 deletions(-) >> >> -- >> 2.1.4 > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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