Re: [Qemu-devel] [PATCH v4 18/29] vhost+postcopy: Resolve client address

[Marc-André Lureau]

Hi

On Thu, Mar 8, 2018 at 8:58 PM, Dr. David Alan Gilbert (git)
<address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Resolve fault addresses read off the clients UFD into RAMBlock
> and offset, and call back to the postcopy code to ask for the page.
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> Reviewed-by: Peter Xu <address@hidden>

Reviewed-by: Marc-André Lureau <address@hidden>


> ---
>  hw/virtio/trace-events |  3 +++
>  hw/virtio/vhost-user.c | 31 ++++++++++++++++++++++++++++++-
>  2 files changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index d7e9e1084b..3afd12cfea 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -7,6 +7,9 @@ vhost_region_add_section_abut(const char *name, uint64_t 
> new_size) "%s: 0x%"PRIx
>  vhost_section(const char *name, int r) "%s:%d"
>
>  # hw/virtio/vhost-user.c
> +vhost_user_postcopy_fault_handler(const char *name, uint64_t fault_address, 
> int nregions) "%s: @0x%"PRIx64" nregions:%d"
> +vhost_user_postcopy_fault_handler_loop(int i, uint64_t client_base, uint64_t 
> size) "%d: client 0x%"PRIx64" +0x%"PRIx64
> +vhost_user_postcopy_fault_handler_found(int i, uint64_t region_offset, 
> uint64_t rb_offset) "%d: region_offset: 0x%"PRIx64" rb_offset:0x%"PRIx64
>  vhost_user_postcopy_listen(void) ""
>  vhost_user_set_mem_table_postcopy(uint64_t client_addr, uint64_t qhva, int 
> reply_i, int region_i) "client:0x%"PRIx64" for hva: 0x%"PRIx64" reply %d 
> region %d"
>  vhost_user_set_mem_table_withfd(int index, const char *name, uint64_t 
> memory_size, uint64_t guest_phys_addr, uint64_t userspace_addr, uint64_t 
> offset) "%d:%s: size:0x%"PRIx64" GPA:0x%"PRIx64" QVA/userspace:0x%"PRIx64" RB 
> offset:0x%"PRIx64
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index fd65616961..e19b9ef9cf 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -26,6 +26,7 @@
>  #include <sys/socket.h>
>  #include <sys/un.h>
>  #include <linux/vhost.h>
> +#include <linux/userfaultfd.h>
>
>  #define VHOST_MEMORY_MAX_NREGIONS    8
>  #define VHOST_USER_F_PROTOCOL_FEATURES 30
> @@ -974,7 +975,35 @@ out:
>  static int vhost_user_postcopy_fault_handler(struct PostCopyFD *pcfd,
>                                               void *ufd)
>  {
> -    return 0;
> +    struct vhost_dev *dev = pcfd->data;
> +    struct vhost_user *u = dev->opaque;
> +    struct uffd_msg *msg = ufd;
> +    uint64_t faultaddr = msg->arg.pagefault.address;
> +    RAMBlock *rb = NULL;
> +    uint64_t rb_offset;
> +    int i;
> +
> +    trace_vhost_user_postcopy_fault_handler(pcfd->idstr, faultaddr,
> +                                            dev->mem->nregions);
> +    for (i = 0; i < MIN(dev->mem->nregions, u->region_rb_len); i++) {
> +        trace_vhost_user_postcopy_fault_handler_loop(i,
> +                u->postcopy_client_bases[i], 
> dev->mem->regions[i].memory_size);
> +        if (faultaddr >= u->postcopy_client_bases[i]) {
> +            /* Ofset of the fault address in the vhost region */
> +            uint64_t region_offset = faultaddr - u->postcopy_client_bases[i];
> +            if (region_offset < dev->mem->regions[i].memory_size) {
> +                rb_offset = region_offset + u->region_rb_offset[i];

It may be worth to add an assert (i < u->region_rb_len) ?

> +                trace_vhost_user_postcopy_fault_handler_found(i,
> +                        region_offset, rb_offset);
> +                rb = u->region_rb[i];
> +                return postcopy_request_shared_page(pcfd, rb, faultaddr,
> +                                                    rb_offset);
> +            }
> +        }
> +    }
> +    error_report("%s: Failed to find region for fault %" PRIx64,
> +                 __func__, faultaddr);
> +    return -1;
>  }
>
>  /*
> --
> 2.14.3
>
>



-- 
Marc-André Lureau