Code review comment for ~paelzer/ubuntu/+source/qemu:fix-1832622-ppc-spectre-eoan

Patches only analysis (next commit will try to take care of understanding changes):

commit 8ff43ee404d3e295839d1fd4e9e6571ca7a62a66 (v3.1.0-2772-g8ff43ee404)
Author: Suraj Jitindar Singh <email address hidden>
Date: Fri Mar 1 00:19:12 2019

    target/ppc/spapr: Add SPAPR_CAP_CCF_ASSIST

    Introduce a new spapr_cap SPAPR_CAP_CCF_ASSIST to be used to indicate
    the requirement for a hw-assisted version of the count cache flush
    workaround.

    The count cache flush workaround is a software workaround which can be
    used to flush the count cache on context switch. Some revisions of
    hardware may have a hardware accelerated flush, in which case the
    software flush can be shortened. This cap is used to set the
    availability of such hardware acceleration for the count cache flush
    routine.

    The availability of such hardware acceleration is indicated by the
    H_CPU_CHAR_BCCTR_FLUSH_ASSIST flag being set in the characteristics
    returned from the KVM_PPC_GET_CPU_CHAR ioctl.

    Signed-off-by: Suraj Jitindar Singh <email address hidden>
    Message-Id: <email address hidden>
    [dwg: Small style fixes]
    Signed-off-by: David Gibson <email address hidden>

Your comment:

"remove context dependencies on post-2.11 capabilities and migration state"

was made due to positional changes, right ?

Cause I can see only the enum index as diff from upstream.

Anyway, check my next comment (about capabilities) before answering this =o).

---- All other commits are just like upstream:

commit 399b2896d4948a1ec0278d896ea3a561df768d64 (v3.1.0-2771-g399b2896d4)
Author: Suraj Jitindar Singh <email address hidden>
Date: Fri Mar 1 00:19:11 2019

    target/ppc/spapr: Add workaround option to SPAPR_CAP_IBS

    The spapr_cap SPAPR_CAP_IBS is used to indicate the level of capability
    for mitigations for indirect branch speculation. Currently the available
    values are broken (default), fixed-ibs (fixed by serialising indirect
    branches) and fixed-ccd (fixed by diabling the count cache).

    Introduce a new value for this capability denoted workaround, meaning that
    software can work around the issue by flushing the count cache on
    context switch. This option is available if the hypervisor sets the
    H_CPU_BEHAV_FLUSH_COUNT_CACHE flag in the cpu behaviours returned from
    the KVM_PPC_GET_CPU_CHAR ioctl.

    Signed-off-by: Suraj Jitindar Singh <email address hidden>
    Message-Id: <email address hidden>
    Signed-off-by: David Gibson <email address hidden>

commit 8fea70440eb0d095442de7e80d586a285cf96be5 (v2.12.0-1230-g8fea70440e)
Author: Suraj Jitindar Singh <email address hidden>
Date: Fri May 11 03:25:07 2018

    target/ppc: Factor out the parsing in kvmppc_get_cpu_characteristics()

    Factor out the parsing of struct kvm_ppc_cpu_char in
    kvmppc_get_cpu_characteristics() into a separate function for each cap
    for simplicity.

    Signed-off-by: Suraj Jitindar Singh <email address hidden>
    Signed-off-by: David Gibson <email address hidden>

commit 8c5909c41916f25b47bfdc465059a926603c1319 (v2.11.0-1603-g8c5909c419)
Author: Suraj Jitindar Singh <email address hidden>
Date: Wed Feb 14 22:44:41 2018

    ppc/spapr-caps: Change migration macro to take full spapr-cap name

    Change the macro that generates the vmstate migration field and the needed
    function for the spapr-caps to take the full spapr-cap name. This has
    the benefit of meaning this instance will be picked up when greping
    for the spapr-caps and making it more obvious what this macro is doing.

    Signed-off-by: Suraj Jitindar Singh <email address hidden>
    Signed-off-by: David Gibson <email address hidden>