From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 22 Jul 2019 17:47:09 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20190722164709.GE3035@work-vm> References: <4221bd26-c6a0-6853-e455-aee8239349bd@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4221bd26-c6a0-6853-e455-aee8239349bd@gmail.com> 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: > 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. > --- > 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