Re: [PATCH 3/4] x86/DMI: fix table mapping when one lives above 1Mb

["Roger Pau Monné" <roger.pau@citrix.com>]

On Mon, Nov 23, 2020 at 01:40:30PM +0100, Jan Beulich wrote:
> Use of __acpi_map_table() is kind of an abuse here, and doesn't work
> anymore for the majority of cases if any of the tables lives outside the
> low first Mb. Keep this (ab)use only prior to reaching SYS_STATE_boot,
> primarily to avoid needing to audit whether any of the calls here can
> happen this early in the first place; quite likely this isn't necessary
> at all - at least dmi_scan_machine() gets called late enough.
> 
> For the "normal" case, call __vmap() directly, despite effectively
> duplicating acpi_os_map_memory(). There's one difference though: We
> shouldn't need to establish UC- mappings, WP or r/o WB mappings ought to
> be fine, as the tables are going to live in either RAM or ROM. Short of
> having PAGE_HYPERVISOR_WP and wanting to map the tables r/o anyway, use
> the latter of the two options. The r/o mapping implies some
> constification of code elsewhere in the file. For code touched anyway
> also switch to void (where possible) or uint8_t.
> 
> Fixes: 1c4aa69ca1e1 ("xen/acpi: Rework acpi_os_map_memory() and acpi_os_unmap_memory()")
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks, Roger.