Re: [PATCH] KVM: PPC: Book3S HV: Define usage types for rmap array in guest memslot

[Paul Mackerras <paulus@ozlabs.org>]

On Tue, Aug 20, 2019 at 04:13:49PM +1000, Suraj Jitindar Singh wrote:
> The rmap array in the guest memslot is an array of size number of guest
> pages, allocated at memslot creation time. Each rmap entry in this array
> is used to store information about the guest page to which it
> corresponds. For example for a hpt guest it is used to store a lock bit,
> rc bits, a present bit and the index of a hpt entry in the guest hpt
> which maps this page. For a radix guest which is running nested guests
> it is used to store a pointer to a linked list of nested rmap entries
> which store the nested guest physical address which maps this guest
> address and for which there is a pte in the shadow page table.
> 
> As there are currently two uses for the rmap array, and the potential
> for this to expand to more in the future, define a type field (being the
> top 8 bits of the rmap entry) to be used to define the type of the rmap
> entry which is currently present and define two values for this field
> for the two current uses of the rmap array.
> 
> Since the nested case uses the rmap entry to store a pointer, define
> this type as having the two high bits set as is expected for a pointer.
> Define the hpt entry type as having bit 56 set (bit 7 IBM bit ordering).
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>

Thanks, applied to my kvm-ppc-next branch.

Paul.