Subject: [PATCH v2 0/3] Off-load TLB invalidations to host for !GTSE

From: Bharata B Rao <[email-masked]>
Date: Fri, 26 Jun 2020 18:39:57 +0530

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. 

To easily check the availability of GTSE, it is made an 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.

The actual hcall implementation for KVM isn't included in this
patchset and will be posted separately.

Changes in v2
=============
- Dropped the patch that added H_RPT_INVALIDATE calls for the nested
  case. This patch will be posted separately along with KVM hcall
  implementation.
- Merged first two patches
- A few cleanups
- Rebased to powerpc/next

v1: https://lore.kernel.org/linuxppc-dev/[email-masked]/

H_RPT_INVALIDATE
================
Syntax:
int64   /* H_Success: Return code on successful completion */
        /* H_Busy - repeat the call with the same */
        /* H_Parameter, H_P2, H_P3, H_P4, H_P5 : Invalid parameters */
        hcall(const uint64 H_RPT_INVALIDATE, /* Invalidate RPT translation lookaside information */
              uint64 pid,       /* PID/LPID to invalidate */
              uint64 target,    /* Invalidation target */
              uint64 type,      /* Type of lookaside information */
              uint64 pageSizes,     /* Page sizes */
              uint64 start,     /* Start of Effective Address (EA) range (inclusive) */
              uint64 end)       /* End of EA range (exclusive) */

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.

Type of translation to invalidate (type)
---------------------------------------
NESTED       0x0001  /* Invalidate nested guest partition-scope */
TLB          0x0002  /* Invalidate TLB */
PWC          0x0004  /* Invalidate Page Walk Cache */
PRT          0x0008  /* Invalidate Process Table Entries if NESTED is clear */
PAT          0x0008  /* Invalidate Partition Table Entries if NESTED is set */

A combination of the above can be specified.

Page size mask (pageSizes)
--------------------------
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, type, or pageSizes parameters are
  different from the defined values.
* Return H_PARAMETER if NESTED is set and pid is not a valid nested
  LPID allocated to this partition
* Return H_P5 if (start, end) doesn't form a valid range. Start and end
  should be a valid Quadrant address and  end > start.
* Return H_NotSupported if the partition is not in running in radix
  translation mode.
* May invalidate more translation information than requested.
* 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 NESTED is clear, then invalidate process scoped lookaside information.
  Else pid specifies a nested LPID, and the invalidation is performed
  on nested guest partition table and nested guest partition scope real
  addresses.
* If pid = 0 and NESTED is clear, 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 caller to optimally invalidate ranges that may
  contain mixed page sizes.
* Return H_SUCCESS on success.

Bharata B Rao (2):
  powerpc/mm: Enable 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

 .../include/asm/book3s/64/tlbflush-radix.h    | 15 ++++
 arch/powerpc/include/asm/hvcall.h             | 34 +++++++-
 arch/powerpc/include/asm/mmu.h                |  4 +
 arch/powerpc/include/asm/plpar_wrappers.h     | 50 +++++++++++
 arch/powerpc/kernel/dt_cpu_ftrs.c             |  1 +
 arch/powerpc/kernel/prom_init.c               | 13 +--
 arch/powerpc/mm/book3s64/radix_tlb.c          | 82 +++++++++++++++++--
 arch/powerpc/mm/init_64.c                     |  5 +-
 arch/powerpc/platforms/pseries/lpar.c         |  8 +-
 9 files changed, 195 insertions(+), 17 deletions(-)

-- 
2.21.3