[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: hypercalls with 64-bit results

On 16.06.21 18:04, Jan Beulich wrote:

several years back do_memory_op() in libxc was changed to have "long"
return type. This is because some of the sub-ops return potentially
large values as the hypercall return value (i.e. not in an argument
structure field). This change, however, didn't have the intended
effect from all I can tell, which apparently manifests in the present
two remaining ovmf failures in the staging osstest flights. Anthony
tells me that ovmf as of not very long ago puts the shared info page
at a really high address, thus making the p2m of the guest very large.
Its size gets returned by XENMEM_maximum_gpfn, as function return

Since hypercalls from the tool stack are based on ioctl(), and since
ioctl() has a return type of "int", I'm afraid there's no way we can
deal with this by adjusting function return types in the libraries.
Instead we appear to need either a new privcmd ioctl or new XENMEM_*
subops (for those cases where potentially large values get returned).

I think we can just use a multicall in libxc to wrap the affected


Attachment: OpenPGP_0xB0DE9DD628BF132F.asc
Description: OpenPGP public key

Attachment: OpenPGP_signature
Description: OpenPGP digital signature



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.