> -----Original Message----- > From: Michael S. Tsirkin [mailto:m...@redhat.com] > Sent: Tuesday, March 20, 2018 8:36 PM > To: Zhoujian (jay) <jianjay.z...@huawei.com> > Cc: qemu-devel@nongnu.org; imamm...@redhat.com; Huangweidong (C) > <weidong.hu...@huawei.com>; wangxin (U) <wangxinxin.w...@huawei.com>; Gonglei > (Arei) <arei.gong...@huawei.com>; Liuzhe (Ahriy, Euler) <liuzh...@huawei.com> > Subject: Re: [PATCH v9] vhost: used_memslots refactoring > > On Tue, Mar 20, 2018 at 03:39:17AM +0000, Zhoujian (jay) wrote: > > > > > > > -----Original Message----- > > > From: Michael S. Tsirkin [mailto:m...@redhat.com] > > > Sent: Tuesday, March 20, 2018 10:51 AM > > > To: Zhoujian (jay) <jianjay.z...@huawei.com> > > > Cc: qemu-devel@nongnu.org; imamm...@redhat.com; Huangweidong (C) > > > <weidong.hu...@huawei.com>; wangxin (U) > > > <wangxinxin.w...@huawei.com>; Gonglei > > > (Arei) <arei.gong...@huawei.com>; Liuzhe (Ahriy, Euler) > > > <liuzh...@huawei.com> > > > Subject: Re: [PATCH v9] vhost: used_memslots refactoring > > > > > > On Tue, Mar 20, 2018 at 02:09:34AM +0000, Zhoujian (jay) wrote: > > > > Hi Michael, > > > > > > > > > -----Original Message----- > > > > > From: Michael S. Tsirkin [mailto:m...@redhat.com] > > > > > Sent: Tuesday, March 20, 2018 9:34 AM > > > > > To: Zhoujian (jay) <jianjay.z...@huawei.com> > > > > > Cc: qemu-devel@nongnu.org; imamm...@redhat.com; Huangweidong (C) > > > > > <weidong.hu...@huawei.com>; wangxin (U) > > > > > <wangxinxin.w...@huawei.com>; Gonglei > > > > > (Arei) <arei.gong...@huawei.com>; Liuzhe (Ahriy, Euler) > > > > > <liuzh...@huawei.com> > > > > > Subject: Re: [PATCH v9] vhost: used_memslots refactoring > > > > > > > > > > On Mon, Mar 05, 2018 at 05:12:49PM +0800, Jay Zhou wrote: > > > > > > Used_memslots is shared by vhost kernel and user, it is equal > > > > > > to > > > > > > dev->mem->nregions, which is correct for vhost kernel, but not > > > > > > dev->mem->for > > > > > > vhost user, the latter one uses memory regions that have file > > > > > > descriptor. E.g. a VM has a vhost-user NIC and 8(vhost user > > > > > > memslot upper limit) memory slots, it will be failed to > > > > > > hotplug a new DIMM device since vhost_has_free_slot() finds no > > > > > > free slot left. It should be successful if only part of memory > > > > > > slots have file descriptor, so setting used memslots for > > > > > > vhost-user and vhost- > > > kernel respectively. > > > > > > > > > > > > > > > Below should go after --- > > > > > > > > Thanks for reminding. > > > > > > > > > > > > > > > v7 ... v9: > > > > > > - rebased on the master > > > > > > v2 ... v6: > > > > > > - delete the "used_memslots" global variable, and add it > > > > > > for vhost-user and vhost-kernel separately > > > > > > - refine the function, commit log > > > > > > - used_memslots refactoring > > > > > > > > > > > > Signed-off-by: Igor Mammedov <imamm...@redhat.com> > > > > > > Signed-off-by: Jay Zhou <jianjay.z...@huawei.com> > > > > > > Signed-off-by: Liuzhe <liuzh...@huawei.com> > > > > > > > > > > When built with clang this causes runtime warnings (during make > > > > > check) about misaligned access to structures. > > > > > > > > > > The issue is that vhost_user_prepare_msg requests > > > > > VhostUserMemory which compiler assumes but is then used with a > > > > > pointer into a packed structure - where fields are not aligned. > > > > > > > > Sorry I missed the patch you have sent to fix the alignment, I > > > > have replied to that thread. > > > > > > > > > > > > > > > > > > > > --- > > > > > > hw/virtio/vhost-backend.c | 15 +++++++- > > > > > > hw/virtio/vhost-user.c | 77 ++++++++++++++++++++++++++- > ---- > > > ---- > > > > > ---- > > > > > > hw/virtio/vhost.c | 13 +++---- > > > > > > include/hw/virtio/vhost-backend.h | 6 ++- > > > > > > 4 files changed, 75 insertions(+), 36 deletions(-) > > > > > > > > > > > > diff --git a/hw/virtio/vhost-backend.c > > > > > > b/hw/virtio/vhost-backend.c index 7f09efa..59def69 100644 > > > > > > --- a/hw/virtio/vhost-backend.c > > > > > > +++ b/hw/virtio/vhost-backend.c > > > > > > @@ -15,6 +15,8 @@ > > > > > > #include "hw/virtio/vhost-backend.h" > > > > > > #include "qemu/error-report.h" > > > > > > > > > > > > +static unsigned int vhost_kernel_used_memslots; > > > > > > + > > > > > > static int vhost_kernel_call(struct vhost_dev *dev, unsigned > > > > > > long int > > > > > request, > > > > > > void *arg) { @@ -62,6 +64,11 @@ > > > > > > static int vhost_kernel_memslots_limit(struct vhost_dev *dev) > > > > > > return limit; > > > > > > } > > > > > > > > > > > > +static bool vhost_kernel_has_free_memslots(struct vhost_dev *dev) > { > > > > > > + return vhost_kernel_used_memslots < > > > > > > +vhost_kernel_memslots_limit(dev); } > > > > > > + > > > > > > static int vhost_kernel_net_set_backend(struct vhost_dev *dev, > > > > > > struct > > > > > > vhost_vring_file > > > > > > *file) { @@ -233,11 +240,16 @@ static void > > > > > > vhost_kernel_set_iotlb_callback(struct vhost_dev *dev, > > > > > > qemu_set_fd_handler((uintptr_t)dev->opaque, NULL, > > > > > > NULL, NULL); } > > > > > > > > > > > > +static void vhost_kernel_set_used_memslots(struct vhost_dev *dev) > { > > > > > > + vhost_kernel_used_memslots = dev->mem->nregions; } > > > > > > + > > > > > > static const VhostOps kernel_ops = { > > > > > > .backend_type = VHOST_BACKEND_TYPE_KERNEL, > > > > > > .vhost_backend_init = vhost_kernel_init, > > > > > > .vhost_backend_cleanup = vhost_kernel_cleanup, > > > > > > - .vhost_backend_memslots_limit = > vhost_kernel_memslots_limit, > > > > > > + .vhost_backend_has_free_memslots = > > > > > > + vhost_kernel_has_free_memslots, > > > > > > .vhost_net_set_backend = vhost_kernel_net_set_backend, > > > > > > .vhost_scsi_set_endpoint = vhost_kernel_scsi_set_endpoint, > > > > > > .vhost_scsi_clear_endpoint = > > > > > > vhost_kernel_scsi_clear_endpoint, @@ -264,6 +276,7 @@ static > > > > > > const VhostOps kernel_ops = { #endif /* CONFIG_VHOST_VSOCK */ > > > > > > .vhost_set_iotlb_callback = > vhost_kernel_set_iotlb_callback, > > > > > > .vhost_send_device_iotlb_msg = > > > > > > vhost_kernel_send_device_iotlb_msg, > > > > > > + .vhost_set_used_memslots = > > > > > > + vhost_kernel_set_used_memslots, > > > > > > }; > > > > > > > > > > > > int vhost_set_backend_type(struct vhost_dev *dev, > > > > > > VhostBackendType > > > > > > backend_type) diff --git a/hw/virtio/vhost-user.c > > > > > > b/hw/virtio/vhost-user.c index 41ff5cf..ef14249 100644 > > > > > > --- a/hw/virtio/vhost-user.c > > > > > > +++ b/hw/virtio/vhost-user.c > > > > > > @@ -163,6 +163,8 @@ static VhostUserMsg m __attribute__ > > > > > > ((unused)); > > > > > > /* The version of the protocol we support */ > > > > > > #define VHOST_USER_VERSION (0x1) > > > > > > > > > > > > +static bool vhost_user_free_memslots = true; > > > > > > + > > > > > > struct vhost_user { > > > > > > CharBackend *chr; > > > > > > int slave_fd; > > > > > > @@ -330,12 +332,43 @@ static int > > > > > > vhost_user_set_log_base(struct vhost_dev > > > > > *dev, uint64_t base, > > > > > > return 0; > > > > > > } > > > > > > > > > > > > +static int vhost_user_prepare_msg(struct vhost_dev *dev, > > > > > > +VhostUserMemory > > > > > *mem, > > > > > > + int *fds) { > > > > > > + int i, fd; > > > > > > + > > > > > > + vhost_user_free_memslots = true; > > > > > > + for (i = 0, mem->nregions = 0; i < dev->mem->nregions; ++i) { > > > > > > + struct vhost_memory_region *reg = dev->mem->regions + i; > > > > > > + ram_addr_t offset; > > > > > > + MemoryRegion *mr; > > > > > > + > > > > > > + assert((uintptr_t)reg->userspace_addr == reg- > >userspace_addr); > > > > > > + mr = memory_region_from_host((void *)(uintptr_t)reg- > > > > > >userspace_addr, > > > > > > + &offset); > > > > > > + fd = memory_region_get_fd(mr); > > > > > > + if (fd > 0) { > > > > > > + if (mem->nregions == VHOST_MEMORY_MAX_NREGIONS) { > > > > > > + vhost_user_free_memslots = false; > > > > > > + return -1; > > > > > > + } > > > > > > + > > > > > > + mem->regions[mem->nregions].userspace_addr = reg- > > > > > >userspace_addr; > > > > > > + mem->regions[mem->nregions].memory_size = reg- > >memory_size; > > > > > > + mem->regions[mem->nregions].guest_phys_addr = > > > > > > + reg- > > > > > >guest_phys_addr; > > > > > > + mem->regions[mem->nregions].mmap_offset = offset; > > > > > > + fds[mem->nregions++] = fd; > > > > > > + } > > > > > > + } > > > > > > + > > > > > > + return 0; > > > > > > +} > > > > > > + > > > > > > static int vhost_user_set_mem_table(struct vhost_dev *dev, > > > > > > struct vhost_memory *mem) { > > > > > > int fds[VHOST_MEMORY_MAX_NREGIONS]; > > > > > > - int i, fd; > > > > > > - size_t fd_num = 0; > > > > > > + size_t fd_num; > > > > > > bool reply_supported = > > > > > > virtio_has_feature(dev->protocol_features, > > > > > > > > > > > > VHOST_USER_PROTOCOL_F_REPLY_ACK); > > > > > > > > > > > > @@ -348,29 +381,12 @@ static int > > > > > > vhost_user_set_mem_table(struct vhost_dev > > > > > *dev, > > > > > > msg.hdr.flags |= VHOST_USER_NEED_REPLY_MASK; > > > > > > } > > > > > > > > > > > > - for (i = 0; i < dev->mem->nregions; ++i) { > > > > > > - struct vhost_memory_region *reg = dev->mem->regions + i; > > > > > > - ram_addr_t offset; > > > > > > - MemoryRegion *mr; > > > > > > - > > > > > > - assert((uintptr_t)reg->userspace_addr == reg- > >userspace_addr); > > > > > > - mr = memory_region_from_host((void *)(uintptr_t)reg- > > > > > >userspace_addr, > > > > > > - &offset); > > > > > > - fd = memory_region_get_fd(mr); > > > > > > - if (fd > 0) { > > > > > > - if (fd_num == VHOST_MEMORY_MAX_NREGIONS) { > > > > > > - error_report("Failed preparing vhost-user memory > table > > > > > msg"); > > > > > > - return -1; > > > > > > - } > > > > > > - msg.payload.memory.regions[fd_num].userspace_addr = > reg- > > > > > >userspace_addr; > > > > > > - msg.payload.memory.regions[fd_num].memory_size = reg- > > > > > >memory_size; > > > > > > - msg.payload.memory.regions[fd_num].guest_phys_addr = > reg- > > > > > >guest_phys_addr; > > > > > > - msg.payload.memory.regions[fd_num].mmap_offset = > offset; > > > > > > - fds[fd_num++] = fd; > > > > > > - } > > > > > > + if (vhost_user_prepare_msg(dev, &msg.payload.memory, fds) < 0) > { > > > > > > + error_report("Failed preparing vhost-user memory table > msg"); > > > > > > + return -1; > > > > > > } > > > > > > > > > > > > - msg.payload.memory.nregions = fd_num; > > > > > > + fd_num = msg.payload.memory.nregions; > > > > > > > > > > > > if (!fd_num) { > > > > > > error_report("Failed initializing vhost-user memory map, " > > > > > > @@ -886,9 +902,9 @@ static int vhost_user_get_vq_index(struct > > > > > > vhost_dev > > > > > *dev, int idx) > > > > > > return idx; > > > > > > } > > > > > > > > > > > > -static int vhost_user_memslots_limit(struct vhost_dev *dev) > > > > > > +static bool vhost_user_has_free_memslots(struct vhost_dev > > > > > > +*dev) > > > > > > { > > > > > > - return VHOST_MEMORY_MAX_NREGIONS; > > > > > > + return vhost_user_free_memslots; > > > > > > } > > > > > > > > > > > > static bool vhost_user_requires_shm_log(struct vhost_dev > > > > > > *dev) @@ > > > > > > -1156,11 +1172,19 @@ vhost_user_crypto_close_session(struct > > > > > > vhost_dev *dev, > > > > > uint64_t session_id) > > > > > > return 0; > > > > > > } > > > > > > > > > > > > +static void vhost_user_set_used_memslots(struct vhost_dev *dev) { > > > > > > + int fds[VHOST_MEMORY_MAX_NREGIONS]; > > > > > > + VhostUserMsg msg; > > > > > > + > > > > > > + vhost_user_prepare_msg(dev, &msg.payload.memory, fds); > > > > > > > > > > Oops. This is something I don't understand. > > > > > > > > > > Why is the message prepared here and then discarded? > > > > > > > > > > > > > The purpose of vhost_user_set_used_memslots() is to set the > > > > boolean value of vhost_user_free_memslots, which indicating > > > > whether there're free memeslots for vhost user. Since there're > > > > code duplicating inside > > > > vhost_user_set_used_memslots() and vhost_user_set_mem_table(), > > > > Igor suggested that we could create a new function to avoid duplicating. > > > > Here, the value of VhostUserMsg is not needed by the caller > > > > vhost_user_set_used_memslots(), so we just discarded. > > > > > > > > Regards, > > > > Jay > > > > > > > > > I think I misunderstood the meaning of that variable. > > > It seems to be set when there are more slots than supported. > > > > Yes. > > > > > > > > What vhost_user_free_memslots implies is that it is set when there > > > are no free slots, even if existing config fits. > > > > > > A better name would be vhost_user_out_of_memslots maybe? > > > > vhost_user_free_memslots is set TRUE by default, if there are more > > slots than supported it is set to FALSE. > > vhost_user_out_of_memslots is another option, I think it should be set > > FALSE by default, if there are more slots than supported it is set to TRUE. > > > > Since two functions vhost_has_free_slot() and the callback > > vhost_backend_has_free_memslots() are using this variable, the name > > vhost_user_free_memslots seems a little matching to these function > > names. > > So vhost_has_free_slot is actually slightly wrong after your patch too.
It should be set to FALSE if the number of slots is equal to the limit, indeed. Regards, Jay > > > > If you still prefer vhost_user_out_of_memslots, pls let me know. > > > > > > > > > > > And I missed the fact that it (as well as the prepare call) can > > > actually fail when out of slots. > > > Shouldn't it return status too? > > > > vhost_user_free_memslots is always set to false when prepare call > > failed, this is what vhost_user_set_used_memslots() wants to do, so > > e.g. when we hotplug memory DIMM devices, it will return false while > calling vhost_has_free_slot(). > > > > So, I think vhost_user_set_used_memslots() doesn't need to handle or > > care about the return status of vhost_user_prepare_msg(), the return > > value is only useful to another caller vhost_user_set_mem_table() > > > > Regards, > > Jay > > So function names are a problem here I think. If the function has an > important side effect it should be reflected in the name. Or we could add a > wrapper which does the right thing. > > -- > MST
