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Re: [PATCH for-4.22 0/4] x86/kexec: Improvements for FRED
- To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Mon, 22 Jun 2026 18:26:16 +0100
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Delivery-date: Mon, 22 Jun 2026 17:26:32 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 19/03/2026 12:25 pm, Andrew Cooper wrote:
> Kexec with FRED happens to already function.
>
> Looking at the logic, several unsafe actions are occuring. Fix the worst of
> them.
>
> Andrew Cooper (4):
> x86/kexec: Stop hooking NMIs with trap_nop()
> x86/kexec: Fix and expands comments for kexec_reloc()
> x86/kexec: Invalidate the IDT earlier in kexec_reloc()
> x86/kexec: Disable FRED earlier in kexec_reloc()
>
> xen/arch/x86/crash.c | 20 +++++-----
> xen/arch/x86/x86_64/kexec_reloc.S | 62 ++++++++++++++++++++++---------
> 2 files changed, 55 insertions(+), 27 deletions(-)
>
This is fully reviewed/acked but fell through the cracks an I didn't get
it committed in time. Sorry.
Please could I request a release ack?
Now that FRED is active by default on AMD hardware in 4.22, a poorly
timed NMI will break transitioning into the crash environment. i.e.
it's fixing a corner-case bug in a new feature for 4.22.
~Andrew
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