Re: [PATCH] x86/xen: fix percpu vcpu_info allocation

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Fri, Nov 24, 2023 at 08:48:52AM +0100, Juergen Gross wrote:
> Today the percpu struct vcpu_info is allocated via DEFINE_PER_CPU(),
> meaning that it could cross a page boundary. In this case registering
> it with the hypervisor will fail, resulting in a panic().
> 
> This can easily be fixed by using DEFINE_PER_CPU_ALIGNED() instead,
> as struct vcpu_info is guaranteed to have a size of 64 bytes, matching
> the cache line size of x86 64-bit processors (Xen doesn't support
> 32-bit processors).
> 
> Fixes: 5ead97c84fa7 ("xen: Core Xen implementation")
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

FWIW, on FreeBSD we also switched to the same approach quite
recently:

https://cgit.freebsd.org/src/commit/sys/xen/xen_common.c?id=20fc5bf7df1db698f2651eaa04a3bc71290e1636

Should have checked the Linux side, sorry.

Roger.