[RFC PATCH v0 0/4] Off-load TLB invalidations to host for !GTSE

[Bharata B Rao]

Hypervisor may choose not to enable Guest Translation Shootdown Enable
(GTSE) option for the guest. When GTSE isn't ON, the guest OS isn't
permitted to use instructions like tblie and tlbsync directly, but is
expected to make hypervisor calls to get the TLB flushed.

This series enables the TLB flush routines in the radix code to
off-load TLB flushing to hypervisor via the newly proposed hcall
H_RPT_INVALIDATE. The specification of this hcall is still evolving
while the patchset is posted here for any early comments.

To easily check the availability of GTSE, it is made an MMU feature.
(TODO: Check if this can be a static key instead of MMU feature)

The OV5 handling and H_REGISTER_PROC_TBL hcall are changed to
handle GTSE as an optionally available feature and to not assume GTSE
when radix support is available.

H_RPT_INVALIDATE
================
Syntax:
int64   /* H_Success: Return code on successful completion */
        /* H_Busy - repeat the call with the same */
        /* H_P2, H_P3, H_P4, H_Parameter: Invalid parameters */
        hcall(const uint64 H_RPT_INVALIDATE, /* Invalidate process scoped RPT lookaside information */
              uint64 pid,       /* PID to invalidate */
              uint64 target,    /* Invalidation target */
              uint64 what,      /* What type of lookaside information */
              uint64 pages,     /* Page sizes */
              uint64 start,     /* Start of Effective Address (EA) range */
              uint64 end)       /* End of EA range */

Invalidation targets (target)
-----------------------------
Core MMU        0x01 /* All virtual processors in the partition */
Core local MMU  0x02 /* Current virtual processor */
Nest MMU        0x04 /* All nest/accelerator agents in use by the partition */
A combination of the above can be specified, except core and core local.

What to invalidate (what)
-------------------------
Reserved        0x0001  /* Reserved */
TLB             0x0002  /* Invalidate TLB */
PWC             0x0004  /* Invalidate Page Walk Cache */
PRS             0x0008  /* Invalidate Process Table Entries */
A combination of the above can be specified.

Page size mask (pages)
----------------------
4K              0x01
64K             0x02
2M              0x04
1G              0x08
All sizes       (-1UL)
A combination of the above can be specified.
All page sizes can be selected with -1.

Semantics: Invalidate radix tree lookaside information
           matching the parameters given.
* Return H_P2, H_P3 or H_P4 if target, what or pages parameters are
  different from the defined values.
* Return H_PARAMETER if (start, end) doesn't form a valid range.
* May invalidate more translation information than was specified.
* If start = 0 and end = -1, set the range to cover all valid addresses.
  Else start and end should be aligned to 4kB (lower 11 bits clear).
* If pid = 0 then valid addresses are quadrant 3 and quadrant 0 spaces,
  Else valid addresses are quadrant 0.
* Pages which are fully covered by the range are to be invalidated.
  Those which are partially covered are considered outside invalidation
  range, which allows a call to optimally invalidate ranges that may
  contain mixed page sizes.
* Return H_SUCCESS on success.

Bharata B Rao (3):
  powerpc/mm: Make GTSE as MMU FTR
  powerpc/prom_init: Ask for Radix GTSE only if supported.
  powerpc/pseries: H_REGISTER_PROC_TBL should ask for GTSE only if
    enabled

Nicholas Piggin (1):
  powerpc/mm/book3s64/radix: Off-load TLB invalidations to host when
    !GTSE

 arch/powerpc/include/asm/hvcall.h         |   1 +
 arch/powerpc/include/asm/mmu.h            |   4 +
 arch/powerpc/include/asm/plpar_wrappers.h |  14 +++
 arch/powerpc/kernel/dt_cpu_ftrs.c         |   2 +
 arch/powerpc/kernel/prom_init.c           |  13 +--
 arch/powerpc/mm/book3s64/radix_tlb.c      | 105 ++++++++++++++++++++--
 arch/powerpc/mm/init_64.c                 |   6 +-
 arch/powerpc/platforms/pseries/lpar.c     |   8 +-
 8 files changed, 137 insertions(+), 16 deletions(-)

-- 
2.21.3