Re: [Qemu-ppc] [PATCH v4 0/8] ISA 3.00 KVM guest support

[Sam Bobroff]

On Fri, Mar 17, 2017 at 03:01:11PM +1100, David Gibson wrote:
> On Thu, Mar 16, 2017 at 05:08:12PM +1100, Sam Bobroff wrote:
> > 
> > ISA 3.00 KVM guest support
> > 
> > Notes for v4:
> > 
> > * Patch "spapr: Small cleanup of PPC MMU enums" has already been accepted,
> >   so it's dropped.
> > * Patches "scripts/update-linux-headers.sh: refactor extra files" and
> >   "scripts/update-linux-headers.sh: add new files for ARM" have been posted 
> > to
> >   qemu-devel separately so are dropped here.
> > * Patch "Update headers using update-linux-headers.sh" is no longer 
> > necessary
> >   because a header update has been done upstream, so it is dropped.
> > 
> > Because KVM will soon provide the necessary infrastructure for KVM guests to
> > run on POWER9 CPUs, we can now start exploiting this new functionality from
> > QEMU. See:
> > https://lists.ozlabs.org/pipermail/linuxppc-dev/2017-January/153433.html
> > 
> > This set aims to support only the following scenarios:
> > * A POWER9 host running in radix mode, running a guest in radix mode.
> > * A POWER9 host running in hash mode, running a guest in hash mode.
> > * A POWER9 host running in hash mode, running a guest in legacy(+) mode.
> > (+) Where legacy means that the guest does not support ISA 3.00.
> > 
> > Hash or radix mode for the host is controlled via the "disable_radix" kernel
> > command line parameter: the host will use radix unless disable_radix is 
> > given.
> > For the guest it should be automatically selected to match the host.
> > 
> > Bad legacy guests: There are some recent kernels (e.g. 4.9) that will, when 
> > run
> > as a KVM guest and if the ibm,pa-features entry in the device tree has the
> > Radix MMU bit set, attempt to initialize the MMU as if they were a host 
> > (which
> > will cause them to crash). To avoid exposing this problem, the Radix MMU bit
> > is removed from ibm,pa-features when a legacy guest is detected.
> > 
> > Notes:
> > * This set is based on David Gibson's ppc-for-2.10 branch, available
> > in his tree on github at https://github.com/dgibson/qemu.git .
> > * This set sits on top of Suraj's recent patch set titled "target/ppc:
> > Implement POWER9 pseries TCG legacy support", archved here:
> > https://lists.gnu.org/archive/html/qemu-ppc/2017-03/msg00004.html .
> > * I have merged my patch that implements with h_register_process_table()
> > with the patches Suraj's work that implement the same function for TCG (to 
> > make
> > integration easier). The patches are now:
> >     * target/ppc: Add new H-CALL shells for in memory table translation
> >     * target/ppc: Implement H_REGISTER_PROCESS_TABLE H_CALL
> > * The set itself and Suraj's related work are availbe in a branch called 
> > p9-cas,
> > from my tree on github at https://github.com/sambltc/qemu.git .
> 
> This is basically good, but there are enough nits that I'd like a
> respin (most of the problems I'd just fix during merge, but some of
> the compile failures are a bit more fiddly).

No problem, I'll have another draft out ASAP. Thanks for all the
reviewing :-)

> For future reference, before sending can you, as a matter of course:
>    * Compile test for all targets (use ./configure with no parameters)
>    * Do the above on both ppc and x86 hosts
>    * Run checkpatch.pl on all patches

Sure. (I do already run checkpatch automatically.)

> 
> > 
> > Patch set changelog follows:
> > 
> > ====== Version 3 -> version 4: ======
> > 
> > Patch 1/8: spapr: Add ibm,processor-radix-AP-encodings to the device tree
> > * Don't clear ppc->radix_page_info when not using KVM.
> > 
> > Patch 3/8: spapr: Only setup HPT if necessary
> > * Fixed typo in title.
> > * Reworked to track that no HPT has been allocated using the GR bit of PATB.
> > 
> > Patch 5/8: target/ppc: Implement H_REGISTER_PROCESS_TABLE H_CALL
> > * h_register_process_table(): Moved bit ops out of macro definitions and
> >   associated code reorganization.
> > 
> > Patch 7/8: spapr: Enable ISA 3.0 MMU mode selection via CAS
> > * spapr_populate_pa_features(): Removed explicit array length specifier. It
> >   would be nice toadd a QEMU_BUILD_BUG_ON() in it's place but it's not 
> > possible
> >   because the pa_features array can't be const.
> > 
> > ====== Version 2 -> version 3: ======
> > 
> > Patch 2/13: spapr: Small cleanup of PPC MMU enums
> > * Slight changes due to reordering patches.
> > * Fixed additional uses of POWERPC_MMU_3_00 caused by reordering.
> > 
> > Patch 8/13: spapr: Only setup HTP if necessary.
> > * in spapr_setup_hpt_and_vrma() replaced MACHINE(qdev_get_machine()) with 
> > MACHINE(spapr).
> > 
> > Patch 9/13: target/ppc: Add new H-CALL shells for in memory table 
> > translation
> > * Brought in from Suraj's work.
> > 
> > Patch 10/13: target/ppc: Implement H_REGISTER_PROCESS_TABLE H_CALL
> > * KVM-only implementation of h_register_process_table() integrated into the 
> > TCG version.
> > 
> > Patch 12/13: spapr: Enable ISA 3.0 MMU mode selection via CAS
> > * Added some terse documentation for the ibm,pa_features bits for ISA 3.00.
> > * Shortened the error reports for guest termination a little.
> > 
> > Patch 13/13: spapr: Workaround for broken radix guests
> > * Legacy guest detection now uses the ISA 3.00 bit in option vector 1.
> > 
> > ====== Version 1 -> version 2: ======
> > 
> > Patch 4/14: scripts/update-linux-headers.sh: refactor extra files
> > I've factored the script to make it easier to add new files.
> > 
> > Patch 5/14: scripts/update-linux-headers.sh: add new files for ARM
> > * Added the two new arm headers.
> > 
> > Patch 6/14: Move virtio_mmio.h to fix update-linux-headers.sh
> > * FWIW, here's one way of fixing it.
> > 
> > Patch 7/14: Update headers using update-linux-headers.sh
> > * Added information about where the headers came from.
> > 
> > Patch 8/14: spapr: Add ibm,processor-radix-AP-encodings to the device tree
> > * ppc_radix_page_info now kept in native format, conversion to BE done when 
> > adding to the device tree.
> > * radix_page_info moved into the CPU class, cleaning up some code.
> > 
> > Patch 9/14: target-ppc: support KVM_CAP_PPC_MMU_RADIX, 
> > KVM_CAP_PPC_MMU_HASH_V3
> > * cap_mmu_hash renamed to cap_mmu_hash_v3.
> > 
> > Patch 10/14: spapr: Only setup HTP if necessary.
> > * This patch has been mostly rewritten to move the late HPT allocation to 
> > CAS.
> > This allows a guest to start in radix mode (when it's in real mode) and then
> > change to hash, even if it is a legacy guest and will not call
> > h_register_process_table().
> > * Added an exported function to spapr.c to perform HPT allocation and adjust
> > the vrma if necessary. This makes it possible to allocate the HPT from
> > h_client_architecture_support() in spapr_hcall.c.
> > 
> > Patch 11/14: spapr: Add h_register_process_table() hypercall
> > * I haven't addressed review comments for this patch because it overlaps 
> > with
> > Suraj's implementation of the same function and we'll work together to
> > integrate them.
> > 
> > Patch 13/14: spapr: Enable ISA 3.0 MMU mode selection via CAS
> > * Unused bits removed.
> > * Logic and bit definitions changed due to architectural change.
> > * Cleanly terminate QEMU if the guest requests an unavailable mode (as 
> > required
> >   by the new architecture).
> > * Legacy guest workaround moved to it's own patch.
> > * I'm sorry for the bitfield constants in spapr_dt_ov5_platform_support() 
> > but
> >   there don't seem to be convienent macros for converting an option vector
> >   specifier (OV_BIT(x,y)) into a byte-mask. I'm open to suggestions.
> > 
> > 
> > Sam Bobroff (6):
> >   spapr: Add ibm,processor-radix-AP-encodings to the device tree
> >   target-ppc: support KVM_CAP_PPC_MMU_RADIX, KVM_CAP_PPC_MMU_HASH_V3
> >   spapr: Only setup HPT if necessary
> >   spapr: move spapr_populate_pa_features()
> >   spapr: Enable ISA 3.0 MMU mode selection via CAS
> >   spapr: Workaround for broken radix guests
> > 
> > Suraj Jitindar Singh (2):
> >   target/ppc: Add new H-CALL shells for in memory table translation
> >   target/ppc: Implement H_REGISTER_PROCESS_TABLE H_CALL
> > 
> >  hw/ppc/spapr.c              | 228 
> > ++++++++++++++++++++++++++++++--------------
> >  hw/ppc/spapr_hcall.c        | 179 +++++++++++++++++++++++++++++++++-
> >  include/hw/ppc/spapr.h      |   6 ++
> >  include/hw/ppc/spapr_ovec.h |   8 ++
> >  include/sysemu/kvm.h        |   1 +
> >  target/ppc/cpu-qom.h        |   1 +
> >  target/ppc/cpu.h            |   4 +
> >  target/ppc/kvm.c            |  62 ++++++++++++
> >  target/ppc/kvm_ppc.h        |  14 +++
> >  9 files changed, 427 insertions(+), 76 deletions(-)
> > 
> 
> -- 
> David Gibson                  | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au        | minimalist, thank you.  NOT _the_ 
> _other_
>                               | _way_ _around_!
> http://www.ozlabs.org/~dgibson