On 11/06/2025 15:49, Stewart Hildebrand wrote:
> On 6/10/25 03:27, Orzel, Michal wrote:
>> On 09/06/2025 20:34, Stewart Hildebrand wrote:
>>> Similarly to fba1b0974dd8, when a device is passed through to a
>>> direct-map dom0less domU, the xen,reg ranges may overlap with the
>>> extended regions. Remove xen,reg from direct-map domU extended regions.
>>>
>>> Take the opportunity to update the comment ahead of find_memory_holes().
>>>
>>> Signed-off-by: Stewart Hildebrand <stewart.hildebr...@amd.com>
>>> ---
>>> v3->v4:
>>> * conditionally allocate xen_reg
>>> * use rangeset_report_ranges()
>>> * make find_unallocated_memory() cope with NULL entry
>>>
>>> v2->v3:
>>> * new patch
>>> ---
>>> xen/arch/arm/domain_build.c | 77 +++++++++++++++++++++++++--
>>> xen/common/device-tree/domain-build.c | 5 ++
>>> 2 files changed, 77 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>>> index 590f38e52053..6632191cf602 100644
>>> --- a/xen/arch/arm/domain_build.c
>>> +++ b/xen/arch/arm/domain_build.c
>>> @@ -792,15 +792,17 @@ static int __init handle_pci_range(const struct
>>> dt_device_node *dev,
>>> }
>>>
>>> /*
>>> - * Find the holes in the Host DT which can be exposed to Dom0 as extended
>>> - * regions for the special memory mappings. In order to calculate regions
>>> - * we exclude every addressable memory region described by "reg" and
>>> "ranges"
>>> - * properties from the maximum possible addressable physical memory range:
>>> + * Find the holes in the Host DT which can be exposed to Dom0 or a
>>> direct-map
>>> + * domU as extended regions for the special memory mappings. In order to
>>> + * calculate regions we exclude every addressable memory region described
>>> by
>>> + * "reg" and "ranges" properties from the maximum possible addressable
>>> physical
>>> + * memory range:
>>> * - MMIO
>>> * - Host RAM
>>> * - PCI aperture
>>> * - Static shared memory regions, which are described by special property
>>> * "xen,shared-mem"
>>> + * - xen,reg mappings
>>> */
>>> static int __init find_memory_holes(const struct kernel_info *kinfo,
>>> struct membanks *ext_regions)
>>> @@ -882,6 +884,13 @@ static int __init find_memory_holes(const struct
>>> kernel_info *kinfo,
>>> }
>>> }
>>>
>>> + if ( kinfo->xen_reg_assigned )
>>> + {
>>> + res = rangeset_subtract(mem_holes, kinfo->xen_reg_assigned);
>>> + if ( res )
>>> + goto out;
>>> + }
>>> +
>>> start = 0;
>>> end = (1ULL << p2m_ipa_bits) - 1;
>>> res = rangeset_report_ranges(mem_holes, PFN_DOWN(start), PFN_DOWN(end),
>>> @@ -962,11 +971,48 @@ static int __init find_domU_holes(const struct
>>> kernel_info *kinfo,
>>> return res;
>>> }
>>>
>>> +static int __init count(unsigned long s, unsigned long e, void *data)
>>> +{
>>> + unsigned int *cnt = data;
>>> +
>>> + (*cnt)++;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int __init rangeset_to_membank(unsigned long s_gfn, unsigned long
>>> e_gfn,
>>> + void *data)
>>> +{
>>> + struct membanks *membank = data;
>>> + paddr_t s = pfn_to_paddr(s_gfn);
>>> + paddr_t e = pfn_to_paddr(e_gfn + 1) - 1;
>> Why do you subtract 1 here if ...
>>
>>> +
>>> + if ( membank->nr_banks >= membank->max_banks )
>>> + return 0;
>>> +
>>> + membank->bank[membank->nr_banks].start = s;
>>> + membank->bank[membank->nr_banks].size = e - s + 1;
>> you add it again here.
>
> To be consistent with add_ext_regions() and add_hwdom_free_regions(),
> but I suppose there's no need for that. I'll drop the extraneous -1 and
> +1.
>
>>> + membank->nr_banks++;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> static int __init find_host_extended_regions(const struct kernel_info
>>> *kinfo,
>>> struct membanks *ext_regions)
>>> {
>>> int res;
>>> struct membanks *gnttab = membanks_xzalloc(1, MEMORY);
>>> + struct membanks *xen_reg =
>>> + kinfo->xen_reg_assigned
>>> + ? ({
>>> + unsigned int xen_reg_cnt = 0;
>>> +
>>> + rangeset_report_ranges(kinfo->xen_reg_assigned, 0,
>>> + PFN_DOWN((1ULL << p2m_ipa_bits) - 1),
>>> count,
>>> + &xen_reg_cnt);
>> This does not look really nice with ({. Why can't we create a helper
>> function to
>> report the count for xen_reg_assigned and call it here? You could then also
>> open
>> code your 'count' function that is not used by anything else and is quite
>> ambiguous.
>
> If I'm reading this right, I think you're suggesting something like this
> (in domain_build.c):
>
> static unsigned int __init count_ranges(struct rangeset *r)
> {
> unsigned int xen_reg_cnt = 0;
>
> rangeset_report_ranges(r,
> 0,
> PFN_DOWN((1ULL << p2m_ipa_bits) - 1),
> ({
> int count(unsigned long s, unsigned long e,
> void *data)
> {
> unsigned int *cnt = data;
>
> (*cnt)++;
>
> return 0;
> }
> count;
> }),
> &xen_reg_cnt);
>
> return xen_reg_cnt;
> }
>
> ...
>
> struct membanks *xen_reg =
> kinfo->xen_reg_assigned
> ? membanks_xzalloc(count_ranges(kinfo->xen_reg_assigned), MEMORY)
> : NULL;
>
>
> However, the open-coded/anonymous count function, aside from being a
> compiler extension, doesn't seem to play well with __init. As written,
> this doesn't link:
Sorry, I don't know why I wrote to open code count(). In conclusion my remark
was to place this code in a separate function to avoid ({ in
find_host_extended_regions(). So there will be count() helper and
count_ranges().
~Michal
