On Fri, 29 Dec 2017 10:37:40 +0000 "Zhoujian (jay)" <jianjay.z...@huawei.com> wrote:
> Hi Igor, > > > -----Original Message----- > > From: Igor Mammedov [mailto:imamm...@redhat.com] > > Sent: Friday, December 29, 2017 5:31 PM > > To: Zhoujian (jay) <jianjay.z...@huawei.com> > > Cc: qemu-devel@nongnu.org; Huangweidong (C) <weidong.hu...@huawei.com>; > > m...@redhat.com; wangxin (U) <wangxinxin.w...@huawei.com>; Liuzhe (Cloud > > Open Labs, NFV) <gary.liu...@huawei.com>; Gonglei (Arei) > > <arei.gong...@huawei.com> > > Subject: Re: [Qemu-devel] [PATCH v3] vhost: add used memslot number for > > vhost-user and vhost-kernel separately > > > > On Fri, 29 Dec 2017 10:35:11 +0800 > > Jay Zhou <jianjay.z...@huawei.com> wrote: > > > > > Used_memslots is equal to dev->mem->nregions now, it is true for vhost > > > kernel, but not for vhost user, which uses the memory regions that > > > have file descriptor. In fact, not all of the memory regions have file > > > descriptor. > > > It is usefully in some scenarios, e.g. used_memslots is 8, and only > > > 5 memory slots can be used by vhost user, it is failed to hotplug a > > > new DIMM memory because vhost_has_free_slot just returned false, > > > however we can hotplug it safely in fact. > > > > > > Meanwhile, instead of asserting in vhost_user_set_mem_table(), error > > > number is used to gracefully prevent device to start. This fixed the > > > VM crash issue. > > > > below mostly style related comments, > > otherwise patch looks good to me > > > > > > Suggested-by: Igor Mammedov <imamm...@redhat.com> > > > Signed-off-by: Jay Zhou <jianjay.z...@huawei.com> > > > Signed-off-by: Zhe Liu <gary.liu...@huawei.com> > > > --- > > > hw/virtio/vhost-backend.c | 14 +++++++ > > > hw/virtio/vhost-user.c | 84 +++++++++++++++++++++++++++++--- > > ------- > > > hw/virtio/vhost.c | 16 ++++---- > > > include/hw/virtio/vhost-backend.h | 4 ++ > > > 4 files changed, 91 insertions(+), 27 deletions(-) > > > > > > diff --git a/hw/virtio/vhost-backend.c b/hw/virtio/vhost-backend.c > > > index 7f09efa..866718c 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) { @@ -233,6 +235,16 @@ > > > 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 unsigned int vhost_kernel_get_used_memslots(void) > > > +{ > > > + return vhost_kernel_used_memslots; } > > > + > > > static const VhostOps kernel_ops = { > > > .backend_type = VHOST_BACKEND_TYPE_KERNEL, > > > .vhost_backend_init = vhost_kernel_init, @@ -264,6 +276,8 @@ > > > 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, > > > + .vhost_get_used_memslots = vhost_kernel_get_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 093675e..0f913be 100644 > > > --- a/hw/virtio/vhost-user.c > > > +++ b/hw/virtio/vhost-user.c > > > @@ -122,6 +122,8 @@ static VhostUserMsg m __attribute__ ((unused)); > > > /* The version of the protocol we support */ > > > #define VHOST_USER_VERSION (0x1) > > > > > > +static unsigned int vhost_user_used_memslots; > > > + > > > struct vhost_user { > > > CharBackend *chr; > > > int slave_fd; > > > @@ -289,12 +291,53 @@ 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, VhostUserMsg > > *msg, > > > + int *fds) { > > > + int r = 0; > > > + int i, fd; > > > + size_t fd_num = 0; > > fd_num is redundant > > you can use msg->payload.memory.nregions as a counter > > If using msg->payload.memory.nregions as a counter, referencing > the member of msg->payload.memory.regions will be like this: > > msg->payload.memory.regions[msg->payload.memory.nregions].userspace_addr = > ... > msg->payload.memory.regions[msg->payload.memory.nregions].memory_size = ... > > which will make the line more longer... > > > > > > + > > > + for (i = 0; i < dev->mem->nregions; ++i) { > > for (i = 0, msg->payload.memory.nregions = 0; ... > > > > > + 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) { > > instead of shifting below block to the right, I'd write it like this: > > Without this patch, the number of characters for these two lines > > msg.payload.memory.regions[fd_num].userspace_addr = > reg->userspace_addr; > msg.payload.memory.regions[fd_num].guest_phys_addr = > reg->guest_phys_addr; > > are more than 80 already... > > > > > if (msg->payload.memory.nregions == > > VHOST_MEMORY_MAX_NREGIONS) { > > return -1; > > } > > msg->payload.memory.nregions as a counter for vhost-user setting mem table, > while fd_num as a counter for vhost_user_used_memslots, IIUC they can not be > merged into one counter. > > If return -1 when > msg->payload.memory.nregions == VHOST_MEMORY_MAX_NREGIONS, the > vhost_user_used_memslots maybe not assigned correctly. fd_num should > be added by one if fd > 0 regardless of whether msg->payload.memory.nregions > equals to or larger than VHOST_MEMORY_MAX_NREGIONS. why do you need to continue counting beyond VHOST_MEMORY_MAX_NREGIONS? 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