Re: [RFC PATCH 0/8] Derive XSAVE state component offsets from CPUID leaf 0xd where possible

[Paolo Bonzini <pbonzini@redhat.com>]

On 05/07/21 12:46, David Edmondson wrote:
> The offset of XSAVE state components within the XSAVE state area is
> currently hard-coded via reference to the X86XSaveArea structure. This
> structure is accurate for Intel systems at the time of writing, but
> incorrect for newer AMD systems, as the state component for protection
> keys is located differently (offset 0x980 rather than offset 0xa80).
> 
> For KVM and HVF, replace the hard-coding of the state component
> offsets with data derived from CPUID leaf 0xd information.
> 
> TCG still uses the X86XSaveArea structure, as there is no underlying
> CPU to use in determining appropriate values.
> 
> This is a replacement for the changes in
> https://lore.kernel.org/r/20210520145647.3483809-1-david.edmondson@oracle.com,
> which simply modifed the hard-coded offsets for AMD systems.
> 
> Testing on HVF is minimal (it builds and, by observation, the XSAVE
> state component offsets reported to a running VM are accurate on an
> older Intel system).

This looks great, thanks, so I am queuing it.

Paolo

> David Edmondson (8):
>    target/i386: Declare constants for XSAVE offsets
>    target/i386: Consolidate the X86XSaveArea offset checks
>    target/i386: Clarify the padding requirements of X86XSaveArea
>    target/i386: Pass buffer and length to XSAVE helper
>    target/i386: Make x86_ext_save_areas visible outside cpu.c
>    target/i386: Observe XSAVE state area offsets
>    target/i386: Populate x86_ext_save_areas offsets using cpuid where
>      possible
>    target/i386: Move X86XSaveArea into TCG
> 
>   target/i386/cpu.c            |  18 +--
>   target/i386/cpu.h            |  41 ++----
>   target/i386/hvf/hvf-cpu.c    |  34 +++++
>   target/i386/hvf/hvf.c        |   3 +-
>   target/i386/hvf/x86hvf.c     |  19 ++-
>   target/i386/kvm/kvm-cpu.c    |  36 +++++
>   target/i386/kvm/kvm.c        |  52 +------
>   target/i386/tcg/fpu_helper.c |   1 +
>   target/i386/tcg/tcg-cpu.c    |  20 +++
>   target/i386/tcg/tcg-cpu.h    |  57 ++++++++
>   target/i386/xsave_helper.c   | 267 ++++++++++++++++++++++++++---------
>   11 files changed, 381 insertions(+), 167 deletions(-)
>