Re: [win-pv-devel] [PATCH 1/2] Add foreign page mapping functions to the GNTTAB interface

[RafaÅ WojdyÅa <omeg@xxxxxxxxxxxxxxxxxxxxxx>]

On 2015-09-04 14:39, RafaÅ WojdyÅa wrote:
> On 2015-09-04 10:58, Paul Durrant wrote:
>>> -----Original Message-----
>>> From: win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx [mailto:win-pv-devel-
>>> bounces@xxxxxxxxxxxxxxxxxxxx] On Behalf Of Rafal Wojdyla
>>> Sent: 25 August 2015 17:16
>>> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
>>> Subject: [win-pv-devel] [PATCH 1/2] Add foreign page mapping functions to
>>> the GNTTAB interface
>>>
>>> +__checkReturn
>>> +XEN_API
>>> +NTSTATUS
>>> +GrantTableMapForeignPage(
>>> +    IN  USHORT                  Domain,
>>> +    IN  ULONG                   GrantRef,
>>> +    IN  PHYSICAL_ADDRESS        Address,
>>> +    IN  BOOLEAN                 ReadOnly,
>>> +    OUT ULONG                   *Handle
>>> +    )
>>> +{
>>> +    struct gnttab_map_grant_ref op;
>>> +    LONG_PTR rc;
>>> +    NTSTATUS status;
>>> +
>>> +    RtlZeroMemory(&op, sizeof(op));
>>> +    op.dom = Domain;
>>> +    op.ref = GrantRef;
>>> +    op.flags = GNTMAP_host_map;
>>> +    if (ReadOnly)
>>> +        op.flags |= GNTMAP_readonly;
>>> +    op.host_addr = Address.QuadPart;
>>> +
>>> +    rc = GrantTableOp(GNTTABOP_map_grant_ref, &op, 1);
>>> +
>>> +    if (rc < 0) {
>>> +        ERRNO_TO_STATUS(-rc, status);
>>> +        goto fail1;
>>> +    }
>>> +
>>> +    if (op.status != GNTST_okay) {
>>> +        status = STATUS_UNSUCCESSFUL;
>>> +        goto fail2;
>>> +    }
>>> +
>>> +    *Handle = op.handle;
>>> +
>>> +    return STATUS_SUCCESS;
>>> +
>>> +fail2:
>>> +    Error("fail2: op.status = %d\n", op.status);
>>
>> In general I've tried to keep 'Error' messages other than 'fail1:'
plain. Rather than just setting status to unsuccessful and logging the
raw grant status here it would be nicer to have a GNTST_TO_STATUS()
macro to set status to something meaningful and then just log that in
the 'fail1:' below.
> Noted.
Unfortunately most of the GNTST_* values don't really have any
meaningful NTSTATUS equivalents. Any ideas on how to approach this? I
guess we could define custom values but that doesn't sound ideal...

-- 
RafaÅ WojdyÅa
Qubes Tools for Windows developer
https://www.qubes-os.org/

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