Re: [dpdk-dev] [PATCH v2] vhost: fix add_guest_pages bug

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Tue, Dec 06, 2016 at 01:40:52PM +0800, linhaifeng wrote:
> 在 2016/12/6 10:28, Yuanhan Liu 写道:
> > On Thu, Dec 01, 2016 at 07:42:02PM +0800, Haifeng Lin wrote:
> >> When reg_size < page_size the function read in
> >> rte_mem_virt2phy would not return, becausue
> >> host_user_addr is invalid.
> >>
> >> Signed-off-by: Haifeng Lin <haifeng.lin@huawei.com>
> >> ---
> >> v2:
> >> fix TYPO_SPELLING warning
> >> ---
> >>  lib/librte_vhost/vhost_user.c | 10 +++++-----
> >>  1 file changed, 5 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> >> index 6b83c15..ce55e85 100644
> >> --- a/lib/librte_vhost/vhost_user.c
> >> +++ b/lib/librte_vhost/vhost_user.c
> >> @@ -447,14 +447,14 @@ add_guest_pages(struct virtio_net *dev, struct virtio_memory_region *reg,
> >>  	reg_size -= size;
> >>  
> >>  	while (reg_size > 0) {
> >> +		size = reg_size >= page_size ? page_size : reg_size;
> > 
> > I'd use RTE_MIN(reg_size, page_size) here. Also, this patch miss a
> > fixline (http://dpdk.org/dev):
> > 
> >     Fixes: e246896178e6 ("vhost: get guest/host physical address mappings")
> > 
> > Applied to dpdk-next-virtio, with above fixed.
> > 
> > Thanks for the fix!
> > 
> > 	--yliu
> > 
> >>  		host_phys_addr = rte_mem_virt2phy((void *)(uintptr_t)
> >>  						  host_user_addr);
> >> -		add_one_guest_page(dev, guest_phys_addr, host_phys_addr,
> >> -				   page_size);
> >> +		add_one_guest_page(dev, guest_phys_addr, host_phys_addr, size);
> >>  
> >> -		host_user_addr  += page_size;
> >> -		guest_phys_addr += page_size;
> >> -		reg_size -= page_size;
> >> +		host_user_addr  += size;
> >> +		guest_phys_addr += size;
> >> +		reg_size -= size;
> >>  	}
> >>  }
> >>  
> >> -- 
> >> 1.8.3.1
> >>
> > 
> > .
> > 
> 
> Hi，yliu
> The bug would happen like this：
> 
>         -----------------------------
>         |     region                |
>         -----------------------------
>         :                  : remain :
>  --------------            ---------------
>  |  hugepage  |   ...      |   hugepage   |
>  --------------            ---------------
> so the remain reg_size maybe smaller than a hugepage size, and "reg_size -= page_size" is not correct.
> 
> apply all the patch?

Yes, I actually have applied the whole patch, with some minor fixes
stated above. It makes no senes to apply partial of one patch after
all.

	--yliu