From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 26 Jul 2019 09:07:50 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20190726080750.GA2657@work-vm> References: <4221bd26-c6a0-6853-e455-aee8239349bd@gmail.com> <20190722164709.GE3035@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Virtio-fs] Failure as Operation not permitted on aarch64 machine List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Masayoshi Mizuma Cc: virtio-fs@redhat.com * Masayoshi Mizuma (msys.mizuma@gmail.com) wrote: > Hi Dave, > > On 7/22/19 12:47 PM, Dr. David Alan Gilbert wrote: > > * Masayoshi Mizuma (msys.mizuma@gmail.com) wrote: > >> Hello, > > > > Hi Masa, > > > >> I would appreciate if you could help me to resolve following failure. > >> > >> I tried to use virtio-fs on aarch64 [1], however, qemu [2] failed to boot > >> as Operation not permitted. > >> > >> --- > >> # ./virtiofsd -o vhost_user_socket=/tmp/vhostqemu -o source=/tmp/share -o cache=none & > >> > >> # qemu-system-aarch64 -machine virt,accel=kvm,gic-version=3 -cpu host -smp 8 ... [3] > >> > >> UEFI firmware starting. > >> kvm_set_phys_mem: error registering slot: Operation not permitted > >> --- > >> > >> >From the ftrace log, the error happened because kvm_set_user_memory_region() > >> returned as -1 (EPERM). > >> > >> --- > >> qemu-system-aar-28381 [003] .... 6683.601097: tracing_mark_write: kvm_set_user_memory Slot#3 flags=0x0 gpa=0x8000000000 size=0x40000000 ua=0xfffe0ba00000 ret=-1 > >> --- > >> > >> kvm_set_user_memory_region() returned -1 because kvm_arch_prepare_memory_region() > >> in kernel returned as -EPERM. > > > > Right, yes we know this is a problem on aarch64; for aarch we disable > > the DAX mode; if you check out our -dev branches and apply the > > following hack to the kernel: > > > > > > diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c > > index 3f3c018571ee..60a9724f9c71 100644 > > --- a/fs/fuse/virtio_fs.c > > +++ b/fs/fuse/virtio_fs.c > > @@ -541,7 +541,7 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs) > > (u8)VIRTIO_FS_SHMCAP_ID_CACHE); > > if (!have_cache) { > > dev_err(&vdev->dev, "%s: No cache capability\n", __func__); > > - return -ENXIO; > > + return 0; > > } else { > > dev_notice(&vdev->dev, "Cache len: 0x%llx @ 0x%llx\n", > > cache_reg.len, cache_reg.addr); > > > > and start the qemu with: > > -device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs,cache-size=0 > > > > it should start up for you. > > Thanks and the cache-size=0 option works for me! > qemu boots successfully and I can mount the myfs. That's great; our dev world has that fix in, so it'll be in our next release as well. Dave > Thanks! > Masa > > > > >> --- > >> int kvm_arch_prepare_memory_region(struct kvm *kvm, > >> struct kvm_memory_slot *memslot, > >> const struct kvm_userspace_memory_region *mem, > >> enum kvm_mr_change change) > >> { > >> ... > >> if (writable && !(vma->vm_flags & VM_WRITE)) { > >> ret = -EPERM; > >> break; > >> } > >> --- > >> > >> Actually, the /proc/PID/maps showed ua=0xfffe0ba00000 didn't have PROT_WRITE. > >> > >> --- > >> ... > >> 014b0000-014f0000 rw-p 00000000 00:00 0 > >> 1c840000-1d470000 rw-p 00000000 00:00 0 [heap] > >> fffe0ba00000-fffe4ba00000 ---p 00000000 00:00 0 <=== > >> fffe4ba00000-fffe4ba10000 ---p 00000000 00:00 0 > >> fffe4bc00000-fffe4fc00000 rw-p 00000000 00:00 0 > >> fffe4fc00000-fffe4fc10000 ---p 00000000 00:00 0 > >> fffe4fe00000-fffe53e00000 rw-p 00000000 00:00 0 > >> fffe53e00000-fffe53e10000 ---p 00000000 00:00 0 > >> ... > >> --- > >> > >> I'm not sure why ua=0xfffe0ba00000 didn't have PROT_WRITE because the memory > >> was allocated by qemu_anon_ram_alloc() and it should set PROT_READ | PROT_WRITE. > > > > Because we explicitly mprotect it later (and in current versions we > > allocate with PROT_NONE) - on x86 this works fine, but aarch doesn't > > like it; we've not quite figured the rules why yet. > > > > Dave > > > >> > >> --- > >> qemu-system-aar-28372 [022] .... 6674.795027: tracing_mark_write: qemu_anon_ram_alloc size 1073741824 ptr 0xfffe0ba00000 > >> --- > >> > >> qemu boots successfully if I remove "-device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs", > >> so I suppose the option is related to the failure... > >> > >> > >> [1]: host kernel is 5.2.0. > >> guest kernel is https://github.com/rhvgoyal/linux/, branch: virtio-fs-dev-5.1. > >> > >> [2]: I got the qemu from: > >> https://gitlab.com/virtio-fs/qemu.git > >> > >> [3]: Qemu option is: > >> > >> $QEMU -machine virt,accel=kvm,gic-version=3 \ > >> -cpu host \ > >> -smp 8 \ > >> -m 4G,maxmem=4G \ > >> -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on \ > >> -numa node,memdev=mem \ > >> -drive file=/usr/share/AAVMF/AAVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on \ > >> -drive file=$VARS,if=pflash,format=raw,unit=1 \ > >> -chardev socket,id=char0,path=/tmp/vhostqemu \ > >> -device vhost-user-fs-pci,queue-size=1024,chardev=char0,tag=myfs \ > >> -nographic \ > >> -serial mon:stdio \ > >> --trace events=/tmp/qemu-trace-events \ > >> -drive if=virtio,file=/var/lib/libvirt/images/guest.qcow2 > >> > >> Thanks, > >> Masa > >> > >> _______________________________________________ > >> Virtio-fs mailing list > >> Virtio-fs@redhat.com > >> https://www.redhat.com/mailman/listinfo/virtio-fs > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK