x86/hyperv: Add comments about hv_vpset and var size hypercall input args

Current code varies in how the size of the variable size input header
for hypercalls is calculated when the input contains s

x86/hyperv: Add comments about hv_vpset and var size hypercall input args

Current code varies in how the size of the variable size input header
for hypercalls is calculated when the input contains struct hv_vpset.
Surprisingly, this variation is correct, as different hypercalls make
different choices for what portion of struct hv_vpset is treated as part
of the variable size input header. The Hyper-V TLFS is silent on these
details, but the behavior has been confirmed with Hyper-V developers.

To avoid future confusion about these differences, add comments to
struct hv_vpset, and to hypercall call sites with input that contains
a struct hv_vpset. The comments describe the overall situation and
the calculation that should be used at each particular call site.

No functional change as only comments are updated.

Signed-off-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <[email protected]>

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hyperv: Add definitions for root partition driver to hv headers

A few additional definitions are required for the mshv driver code
(to follow). Introduce those here and clean up a little bit while
a

hyperv: Add definitions for root partition driver to hv headers

A few additional definitions are required for the mshv driver code
(to follow). Introduce those here and clean up a little bit while
at it.

Signed-off-by: Nuno Das Neves <[email protected]>
Reviewed-by: Roman Kisel <[email protected]>
Reviewed-by: Stanislav Kinsburskii <[email protected]>
Reviewed-by: Tianyu Lan <[email protected]>
Link: https://lore.kernel.org/r/1741980536-3865-10-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1741980536-3865-10-git-send-email-nunodasneves@linux.microsoft.com>

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hyperv: Move hv_current_partition_id to arch-generic code

Move hv_current_partition_id and hv_get_partition_id() to hv_common.c,
and call hv_get_partition_id() on arm64 in hyperv_init(). These aren'

hyperv: Move hv_current_partition_id to arch-generic code

Move hv_current_partition_id and hv_get_partition_id() to hv_common.c,
and call hv_get_partition_id() on arm64 in hyperv_init(). These aren't
specific to x86_64 and will be needed by common code.

Set hv_current_partition_id to HV_PARTITION_ID_SELF by default.

Rename struct hv_get_partition_id to hv_output_get_partition_id, to
make it distinct from the function hv_get_partition_id(), and match
the original Hyper-V struct name.

Remove the BUG()s. Failing to get the id need not crash the machine.

Signed-off-by: Nuno Das Neves <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/1738955002-20821-2-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <[email protected]>
Message-ID: <1738955002-20821-2-git-send-email-nunodasneves@linux.microsoft.com>

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