Re: [Xen-devel] [PATCH v2] libxc: add xc_domain_add_to_physmap_batch to wrap XENMEM_add_to_physmap_batch

[Zhongze Liu <blackskygg@xxxxxxxxx>]

Hi Wei,

2017-06-21 23:44 GMT+08:00 Wei Liu <wei.liu2@xxxxxxxxxx>:
> On Wed, Jun 21, 2017 at 01:29:26AM +0800, Zhongze Liu wrote:
>> This is a preparation for the proposal "allow setting up shared memory areas
>> between VMs from xl config file". See:
>> V2: https://lists.xen.org/archives/html/xen-devel/2017-06/msg02256.html
>> V1: https://lists.xen.org/archives/html/xen-devel/2017-05/msg01288.html
>>
>> The plan is to use XENMEM_add_to_physmap_batch in xl to map foregin pages 
>> from
>> one DomU to another so that the page could be shared. But currently there is 
>> no
>> wrapper for XENMEM_add_to_physmap_batch in libxc, so we just add a wrapper 
>> for
>> it.
>>
>> Signed-off-by: Zhongze Liu <blackskygg@xxxxxxxxx>
>> ---
>> +int xc_domain_add_to_physmap_batch(xc_interface *xch,
>> +                                   domid_t domid,
>> +                                   domid_t foreign_domid,
>> +                                   unsigned int space,
>> +                                   unsigned int size,
>> +                                   xen_ulong_t *idxs,
>> +                                   xen_pfn_t *gpfns,
>> +             .                      int *errs)
>> +{
>> +    int rc;
>> +    DECLARE_HYPERCALL_BOUNCE(idxs, size * sizeof(*idxs), 
>> XC_HYPERCALL_BUFFER_BOUNCE_IN);
>> +    DECLARE_HYPERCALL_BOUNCE(gpfns, size * sizeof(*gpfns), 
>> XC_HYPERCALL_BUFFER_BOUNCE_IN);
>> +    DECLARE_HYPERCALL_BOUNCE(errs, size * sizeof(*errs), 
>> XC_HYPERCALL_BUFFER_BOUNCE_OUT);
>> +
>> +    struct xen_add_to_physmap_batch xatp_batch = {
>> +        .domid = domid,
>> +        .space = space,
>> +        .size = size,
>> +        .u = {.foreign_domid = foreign_domid}
>
> Coding style issue.

Do you mean that I should add a space between '{' and '.' near ".u =
{.foreign" in this line?

>
> Just a note, the struct is different for pre-4.7 and post-4.7 Xen. You
> don't need to implement a version of this function for pre-4.7 Xen.
>
>> +    };
>> +
>> +    if ( xc_hypercall_bounce_pre(xch, idxs)  ||
>> +         xc_hypercall_bounce_pre(xch, gpfns) ||
>> +         xc_hypercall_bounce_pre(xch, errs)  )
>> +    {
>> +        PERROR("Could not bounce memory for XENMEM_add_to_physmap_batch");
>> +        goto out;
>
> rc will be uninitialised in this exit path.
>
>> +    }
>> +
>> +    set_xen_guest_handle(xatp_batch.idxs, idxs);
>> +    set_xen_guest_handle(xatp_batch.gpfns, gpfns);
>> +    set_xen_guest_handle(xatp_batch.errs, errs);
>> +
>> +    rc = do_memory_op(xch, XENMEM_add_to_physmap_batch,
>> +                      &xatp_batch, sizeof(xatp_batch));
>> +
>> +out:
>> +    xc_hypercall_bounce_post(xch, idxs);
>> +    xc_hypercall_bounce_post(xch, gpfns);
>> +    xc_hypercall_bounce_post(xch, errs);
>> +
>> +    return rc;
>> +}
>> +
>>  int xc_domain_claim_pages(xc_interface *xch,
>>                                 uint32_t domid,
>>                                 unsigned long nr_pages)
>> --
>> 2.13.1
>>


Cheers,

Zhongze Liu

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