Re: [Qemu-devel] [PATCH v2] vhost-user: fix VHOST_USER_SET_MEM_TABLE

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Jun 26, 2014 at 11:35:13AM +0000, Damjan Marion (damarion) wrote:
> 
> On 26 Jun 2014, at 13:30, Michael S. Tsirkin <mst@redhat.com> wrote:
> 
> > On Thu, Jun 26, 2014 at 12:22:59PM +0200, Damjan Marion wrote:
> >> Old code was affected by memory gaps which
> >> resulted in buffer pointers pointing to
> >> address outside of the mapped regions.
> >> 
> >> Signed-off-by: Damjan Marion <damarion@cisco.com>
> >> ---
> > 
> > changelog?
> 
> Ok
> 
> > 
> > does not look like all comments have been addressed.
> 
> Like?

I'm sorry you will have to look for them on the list.

> > 
> >> docs/specs/vhost-user.txt |  7 ++++---
> >> exec.c                    |  7 +++++++
> >> hw/virtio/vhost-user.c    | 23 ++++++++++++++---------
> >> include/exec/ram_addr.h   |  1 +
> >> 4 files changed, 26 insertions(+), 12 deletions(-)
> >> 
> >> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
> >> index 2641390..c108d07 100644
> >> --- a/docs/specs/vhost-user.txt
> >> +++ b/docs/specs/vhost-user.txt
> >> @@ -78,13 +78,14 @@ Depending on the request type, payload can be:
> >>    Padding: 32-bit
> >> 
> >>    A region is:
> >> -   ---------------------------------------
> >> -   | guest address | size | user address |
> >> -   ---------------------------------------
> >> +   -----------------------------------------------------------
> >> +   | guest address | size | user address | shared mem offset |
> >> +   -----------------------------------------------------------
> >> 
> >>    Guest address: a 64-bit guest address of the region
> >>    Size: a 64-bit size
> >>    User address: a 64-bit user address
> >> +   Shared mem offset: 64-bit offset where region is located in the shared memory
> >> 
> >> 
> >> In QEMU the vhost-user message is implemented with the following struct:
> >> diff --git a/exec.c b/exec.c
> >> index c849405..a94c583 100644
> >> --- a/exec.c
> >> +++ b/exec.c
> >> @@ -1456,6 +1456,13 @@ int qemu_get_ram_fd(ram_addr_t addr)
> >>     return block->fd;
> >> }
> >> 
> >> +void *qemu_get_ram_block_host_ptr(ram_addr_t addr)
> >> +{
> >> +    RAMBlock *block = qemu_get_ram_block(addr);
> >> +
> >> +    return block->host;
> >> +}
> >> +
> >> /* Return a host pointer to ram allocated with qemu_ram_alloc.
> >>    With the exception of the softmmu code in this file, this should
> >>    only be used for local memory (e.g. video ram) that the device owns,
> >> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> >> index 0df6a93..b9d7baa 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>
> >> @@ -47,6 +48,7 @@ typedef struct VhostUserMemoryRegion {
> >>     uint64_t guest_phys_addr;
> >>     uint64_t memory_size;
> >>     uint64_t userspace_addr;
> >> +    uint64_t shm_offset;
> >> } VhostUserMemoryRegion;
> >> 
> >> typedef struct VhostUserMemory {
> >> @@ -183,10 +185,10 @@ 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);
> >> @@ -212,16 +214,19 @@ 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->guest_phys_addr;
> >> +                msg.memory.regions[fd_num].shm_offset = reg->userspace_addr -
> >> +                    (uint64_t) qemu_get_ram_block_host_ptr(reg->guest_phys_addr);
> >> +                fds[fd_num++] = fd;
> >>             }
> >>         }
> >> +        assert(fd_num <= VHOST_MEMORY_MAX_NREGIONS);
> >> 
> >>         msg.memory.nregions = fd_num;
> >> 
> >> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
> >> index 55ca676..e9eb831 100644
> >> --- a/include/exec/ram_addr.h
> >> +++ b/include/exec/ram_addr.h
> >> @@ -29,6 +29,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
> >>                                    MemoryRegion *mr);
> >> ram_addr_t qemu_ram_alloc(ram_addr_t size, MemoryRegion *mr);
> >> int qemu_get_ram_fd(ram_addr_t addr);
> >> +void *qemu_get_ram_block_host_ptr(ram_addr_t addr);
> >> void *qemu_get_ram_ptr(ram_addr_t addr);
> >> void qemu_ram_free(ram_addr_t addr);
> >> void qemu_ram_free_from_ptr(ram_addr_t addr);
> >> -- 
> >> 1.9.1