On 10.09.2024 10:15, Juergen Gross wrote:
> On 20.08.24 11:56, Jan Beulich wrote:
>> On 20.08.2024 10:20, Juergen Gross wrote:
>>> @@ -838,6 +839,31 @@ void __init xen_do_remap_nonram(void)
>>> pr_info("Remapped %u non-RAM page(s)\n", remapped);
>>> }
>>>
>>> +/*
>>> + * Xen variant of acpi_os_ioremap() taking potentially remapped non-RAM
>>> + * regions into acount.
>>> + * Any attempt to map an area crossing a remap boundary will produce a
>>> + * WARN() splat.
>>> + */
>>> +static void __iomem *xen_acpi_os_ioremap(acpi_physical_address phys,
>>> + acpi_size size)
>>> +{
>>> + unsigned int i;
>>> + struct nonram_remap *remap = xen_nonram_remap;
>>
>> const (also in one of the functions in patch 5)?
>
> Yes.
>
>>
>>> + for (i = 0; i < nr_nonram_remap; i++) {
>>> + if (phys + size > remap->maddr &&
>>> + phys < remap->maddr + remap->size) {
>>> + WARN_ON(phys < remap->maddr ||
>>> + phys + size > remap->maddr + remap->size);
>>> + phys = remap->paddr + phys - remap->maddr;
>>> + break;
>>> + }
>>> + }
>>> +
>>> + return x86_acpi_os_ioremap(phys, size);
>>> +}
>>
>> At least this, perhaps also what patch 5 adds, likely wants to be limited
>> to the XEN_DOM0 case? Or else I wonder whether ...
>>
>>> @@ -850,6 +876,10 @@ void __init xen_add_remap_nonram(phys_addr_t maddr, phys_addr_t paddr,
>>> BUG();
>>> }
>>>
>>> + /* Switch to the Xen acpi_os_ioremap() variant. */
>>> + if (nr_nonram_remap == 0)
>>> + acpi_os_ioremap = xen_acpi_os_ioremap;
>>
>> ... this would actually build when XEN_DOM0=n.
>>
>> I'm actually surprised there's no Dom0-only code section in this file,
>> where the new code could then simply be inserted.
>
> I'd rather make this conditional on CONFIG_ACPI.
Oh, sure.
> Depending on how Xen tools will handle a PV-domain with "e820_host=1" this
> code might be important for domUs, too.
Right, if that's a possibility for PV (I thought that was a HVM-only thing,
yet maybe it really is precisely the other way around), then yes, DomU-s
may too need to cope with unexpected overlaps.
Jan
