Re: [RFC][PATCH 02/34] x86/xen: Remove early "debug" physical address lookups

Jürgen Groß
2024-03-11T13:16:12Z

On 22.02.24 19:39, Dave Hansen wrote:
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> The __pa() facility is subject to debugging checks if CONFIG_DEBUG_VIRTUAL=y.
> One of those debugging checks is whether the physical address is valid
> on the platform. That information is normally available via CPUID. But
> the __pa() code currently looks it up in 'boot_cpu_data' which is not
> fully set up in early Xen PV boot.
>
> The Xen PV code currently tries to get this info with
> get_cpu_address_sizes() which also depends on 'boot_cpu_data' to be at
> least somewhat set up. The result is that the c->x86_phys_bits gets a
> sane value, but not one that has anything to do with the hardware. In
> other words, the CONFIG_DEBUG_VIRTUAL checks are performed with what
> amounts to garbage inputs.
>
> Garbage checks are worse than no check at all. Move over to the
> "nodebug" variant to axe the checks.
>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Juergen Gross <jgross@suse.com>

Reviewed-by: Juergen Gross <jgross@suse.com>

Juergen