On 12/21/21 03:45, Wang, Wei W wrote:
KVM_GET_XSAVE2 and KVM_SET_XSAVE respectively write and read as many
bytes as are returned by KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2), when
invoked on the vm file descriptor. Currently,
KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) will only return a value that is
greater than 4096 bytes if any dynamic features have been enabled with
``arch_prctl()``; this however may change in the future.
Would this make people think that KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) doesn’t
return the value (i.e. return 0) if it is smaller than 4096?
(i.e. KVM_GET_XSAVE2 doesn't work with size < 4096, which isn’t true)
I plan to just reword a bit:
Currently, KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) will only return a size value,
and the value is greater than 4096 bytes if any dynamic features have been enabled with
``arch_prctl()``. More types of values could be returned in the future.
Next refinement:
The size value returned by KVM_CHECK_EXTENSION(KVM_CAP_XSAVE2) will
always be at least 4096. Currently, it is only greater than 4096 if a
dynamic feature has been enabled with ``arch_prctl()``, but this may
change in the future.
(I'm not sure if the first sentence is true in the code, but if not it
is a bug that has to be fixed :)).
Paolo
