NACK: [SRU][N,J][PATCH v2 0/1] disable XSAVES workaround

[Bethany Jamison]

I accidentally sent this before finishing the cover letter, need to add 
impact/fix/test/future issues sections. Will resubmit shortly. Thanks -- 
Bethany

On 9/6/24 12:16 PM, Bethany Jamison wrote:
> BugLink: https://bugs.launchpad.net/bugs/2077321
>
> This patch fixes bug LP#2077321. An older commit (b056346) completely
> disables XSAVES instruction on all AMD ZEN1/2 hardware to avoid a bug
> within that instruction (utilizes XSAVEC instruction instead). This
> method of working around this issue is a bit too broad and causes an
> issue with migrating QEMU VMs from older kernels that use XSAVES to
> newer kernels with XSAVES disabled. This patch implements a commit
> (29ba89f) to improve the workaround. It disables XSAVES only on
> machines that lack a revised piece of microcode that addresses the
> XSAVES bug.
>
> Above Commits:
> b056346 (x86/CPU/AMD: Disable XSAVES on AMD family 0x17) - https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/jammy/commit/?id=b0563468eeac88ebc70559d52a0b66efc37e4e9d
> 29ba89f (x86/CPU/AMD: Improve the erratum 1386 workaround) - https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=29ba89f1895285f06c333546882e0c5ae9a6df23
>
> v2: adjusted to better match the stable patch format
>
> Borislav Petkov (AMD) (1):
>    x86/CPU/AMD: Improve the erratum 1386 workaround
>
>   arch/x86/include/asm/cpu_device_id.h |  8 ++++++++
>   arch/x86/kernel/cpu/amd.c            | 12 ++++++++++++
>   2 files changed, 20 insertions(+)
>