[Xen-devel] HVM (hypercall_grant_table_op) Problem

["马耀" <327801865@xxxxxx>]

Hi:

    I modified the netfont.c of Linux HVM domU installed PVonHVM.In it, I call hypercall_grant_table_op

(GNTTABOP_map_grant_ref...), then dom0 shutdown and restart at once.

    I'm confused about this.

    Before Xen 3.4.3, Xen/arch/x86/HVM/hvm.c look like this:

static long hvm_grant_table_op(unsigned int cmd, XEN_GUEST_HANDLE(void) uop, unsigned int count)
{
    if ( (cmd != GNTTABOP_query_size) && (cmd != GNTTABOP_setup_table) )
        return -ENOSYS; /* all other commands need auditing */
    return do_grant_table_op(cmd, uop, count);
}

    I know it hadn't support all grant_table_op but only two:GNTTABOP_query_size and GNTTABOP_setup_table.

 

    Now, after Xen4.0.0 and later, it look like below:

static long hvm_grant_table_op( unsigned int cmd, XEN_GUEST_HANDLE(void) uop, unsigned int count)
{
    if ( !grant_table_op_is_allowed(cmd) )
        return -ENOSYS; /* all other commands need auditing */
    return do_grant_table_op(cmd, uop, count);
}

static int grant_table_op_is_allowed(unsigned int cmd)
{
    switch (cmd) {
    case GNTTABOP_query_size:
    case GNTTABOP_setup_table:
    case GNTTABOP_set_version:
    case GNTTABOP_copy:
    case GNTTABOP_map_grant_ref:
    case GNTTABOP_unmap_grant_ref:
        return 1;
    default:
        /* all other commands need auditing */
        return 0;
    }
}

    From above, I conclude that I can map a HVM's page to another HVM, just like two PVs.

Am I wrong? Who can give me some suggestion?

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