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    SubjectRe: [PATCH v7 0/7] KVM: x86: Allow Qemu/KVM to use PVH entry point
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    On 17/04/18 01:09, Maran Wilson wrote:
    > For certain applications it is desirable to rapidly boot a KVM virtual
    > machine. In cases where legacy hardware and software support within the
    > guest is not needed, Qemu should be able to boot directly into the
    > uncompressed Linux kernel binary without the need to run firmware.
    >
    > There already exists an ABI to allow this for Xen PVH guests and the ABI
    > is supported by Linux and FreeBSD:
    >
    > https://xenbits.xen.org/docs/unstable/misc/pvh.html
    >
    > This patch series would enable Qemu to use that same entry point for
    > booting KVM guests.

    Hi Maran, what happened to this series (and to the QEMU work)?

    Paolo

    > Changes from v6:
    >
    > * Addressed issues caught by the kbuild test robot:
    > - Restored an #include line that had been dropped by mistake (patch 4)
    > - Removed a pair of #include lines that were no longer needed in a
    > common code file and causing problems for certain 32-bit configs
    > (patchs 4 and 7)
    >
    > Changes from v5:
    >
    > * The interface changes to the x86/HVM start info layout have
    > now been accepted into the Xen tree.
    > * Rebase and merge upstream PVH file changes.
    > * (Patch 6) Synced up to the final version of the header file that was
    > acked and pulled into the Xen tree.
    > * (Patch 1) Fixed typo and removed redundant "def_bool n" line.
    >
    > Changes from v4:
    >
    > Note: I've withheld Juergen's earlier "Reviewed-by" tags from patches
    > 1 and 7 since there were minor changes (mostly just addition of
    > CONFIG_KVM_GUEST_PVH as requested) that came afterwards.
    >
    > * Changed subject prefix from RFC to PATCH
    > * Added CONFIG_KVM_GUEST_PVH as suggested
    > * Relocated the PVH common files to
    > arch/x86/platform/pvh/{enlighten.c,head.S}
    > * Realized I also needed to move the objtool override for those files
    > * Updated a few code comments per reviewer feedback
    > * Sent out a patch of the hvm_start_info struct changes against the Xen
    > tree since that is the canonical copy of the header. Discussions on
    > that thread have resulted in some (non-functional) updates to
    > start_info.h (patch 6/7) and those changes are reflected here as well
    > in order to keep the files in sync. The header file has since been
    > ack'ed for the Xen tree by Jan Beulich.
    >
    > Changes from v3:
    >
    > * Implemented Juergen's suggestion for refactoring and moving the PVH
    > code so that CONFIG_XEN is no longer required for booting KVM guests
    > via the PVH entry point.
    > Functionally, nothing has changed from V3 really, but the patches
    > look completely different now because of all the code movement and
    > refactoring. Some of these patches can be combined, but I've left
    > them very small in some cases to make the refactoring and code
    > movement easier to review.
    > My approach for refactoring has been to create a PVH entry layer that
    > still has understanding and knowledge about Xen vs non-Xen guest types
    > so that it can make run time decisions to handle either case, as
    > opposed to going all the way and re-writing it to be a completely
    > hypervisor agnostic and architecturally pure layer that is separate
    > from guest type details. The latter seemed a bit overkill in this
    > situation. And I've handled the complexity of having to support
    > Qemu/KVM boot of kernels compiled with or without CONFIG_XEN via a
    > pair of xen specific __weak routines that can be overridden in kernels
    > that support Xen guests. Importantly, the __weak routines are for
    > xen specific code only (not generic "guest type" specific code) so
    > there is no clashing between xen version of the strong routine and,
    > say, a KVM version of the same routine. But I'm sure there are many
    > ways to skin this cat, so I'm open to alternate suggestions if there
    > is a compelling reason for not using __weak in this situation.
    >
    > Changes from v2:
    >
    > * All structures (including memory map table entries) are padded and
    > aligned to an 8 byte boundary.
    >
    > * Removed the "packed" attributes and made changes to comments as
    > suggested by Jan.
    >
    > Changes from v1:
    >
    > * Adopted Paolo's suggestion for defining a v2 PVH ABI that includes the
    > e820 map instead of using the second module entry to pass the table.
    >
    > * Cleaned things up a bit to reduce the number of xen vs non-xen special
    > cases.
    >
    >
    > Maran Wilson (7):
    > xen/pvh: Split CONFIG_XEN_PVH into CONFIG_PVH and CONFIG_XEN_PVH
    > xen/pvh: Move PVH entry code out of Xen specific tree
    > xen/pvh: Create a new file for Xen specific PVH code
    > xen/pvh: Move Xen specific PVH VM initialization out of common file
    > xen/pvh: Move Xen code for getting mem map via hcall out of common
    > file
    > xen/pvh: Add memory map pointer to hvm_start_info struct
    > KVM: x86: Allow Qemu/KVM to use PVH entry point
    >
    > MAINTAINERS | 1 +
    > arch/x86/Kbuild | 2 +
    > arch/x86/Kconfig | 14 +++
    > arch/x86/kernel/head_64.S | 2 +-
    > arch/x86/platform/pvh/Makefile | 5 +
    > arch/x86/platform/pvh/enlighten.c | 136 ++++++++++++++++++++++++
    > arch/x86/{xen/xen-pvh.S => platform/pvh/head.S} | 0
    > arch/x86/xen/Kconfig | 3 +-
    > arch/x86/xen/Makefile | 2 -
    > arch/x86/xen/enlighten_pvh.c | 93 +++-------------
    > include/xen/interface/hvm/start_info.h | 63 ++++++++++-
    > 11 files changed, 240 insertions(+), 81 deletions(-)
    > create mode 100644 arch/x86/platform/pvh/Makefile
    > create mode 100644 arch/x86/platform/pvh/enlighten.c
    > rename arch/x86/{xen/xen-pvh.S => platform/pvh/head.S} (100%)
    >

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