|
From: | Nikolay Nikolaev |
Subject: | Re: [Qemu-devel] vhost-user: broken mem regions |
Date: | Wed, 25 Jun 2014 17:13:21 +0300 |
ok, sorry, adding list...
On 25 Jun 2014, at 15:53, Michael S. Tsirkin <address@hidden> wrote:
> On Wed, Jun 25, 2014 at 01:45:09PM +0000, Damjan Marion (damarion) wrote:
>>
>> Michael,
>>
>> there is another issue with commited vhost-user code.
>
> I'm answering just this once, but I have a policy against
> answering off-list mail.
> Pls send follow-ups to the list.
yes, but it will happen that multiple regions have same FD so call to mmap()
>
>> If there is bigger mem allocation (i.e. 4G or 6G of RAM) then
>> we have memory gap and then it happens that buffer pointer points to
>> memory which is not mmaped. I already filled bug report:
>>
>> https://bugs.launchpad.net/qemu/+bug/1333688
>
> FYI I mostly ignore launchpad.
> Because of the unfortunate association with Ubuntu, most bugs
> there are distro-specific.
>
>> Bellow is my proposed change to the code. Two things:
>> - it will require changes on the user side also
>
> why would it?
> format seems unchanged, right?
should look different, I’m still playing with this on user side...
>
>> - not sure if qemu_get_ram_fd() is the best way to get FD
>
> Paolo, what do you think?
>
>> Any comments or better idea how to fix this?
>>
>> Thanks,
>>
>> Damjan
>>
>> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
>> index 0df6a93..89fe5c7 100644
>> --- a/hw/virtio/vhost-user.c
>> +++ b/hw/virtio/vhost-user.c
>> @@ -14,6 +14,7 @@
>> #include "sysemu/kvm.h"
>> #include "qemu/error-report.h"
>> #include "qemu/sockets.h"
>> +#include "exec/ram_addr.h"
>>
>> #include <fcntl.h>
>> #include <unistd.h>
>> @@ -183,10 +184,10 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
>> {
>> VhostUserMsg msg;
>> VhostUserRequest msg_request;
>> - RAMBlock *block = 0;
>> struct vhost_vring_file *file = 0;
>> int need_reply = 0;
>> int fds[VHOST_MEMORY_MAX_NREGIONS];
>> + int i, fd;
>> size_t fd_num = 0;
>>
>> assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
>> @@ -212,14 +213,14 @@ static int vhost_user_call(struct vhost_dev *dev, unsigned long int request,
>> break;
>>
>> case VHOST_SET_MEM_TABLE:
>> - QTAILQ_FOREACH(block, &ram_list.blocks, next)
>> - {
>> - if (block->fd > 0) {
>> - msg.memory.regions[fd_num].userspace_addr =
>> - (uintptr_t) block->host;
>> - msg.memory.regions[fd_num].memory_size = block->length;
>> - msg.memory.regions[fd_num].guest_phys_addr = block->offset;
>> - fds[fd_num++] = block->fd;
>> + for (i = 0; i < dev->mem->nregions; ++i) {
>> + struct vhost_memory_region *reg = dev->mem->regions + i;
>> + fd = qemu_get_ram_fd(reg->guest_phys_addr);
>> + if (fd > 0) {
>> + msg.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
>> + msg.memory.regions[fd_num].memory_size = reg->memory_size;
>> + msg.memory.regions[fd_num].guest_phys_addr = reg->memory_size;
>> + fds[fd_num++] = fd;
>> }
>> }
>>
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