On 6/30/25 5:59 PM, Jan Beulich wrote:
On 10.06.2025 15:05, Oleksii Kurochko wrote:
+ unsigned long nr, mfn_t mfn, p2m_type_t t)
+{
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
+ int rc;
+
+ p2m_write_lock(p2m);
+ rc = p2m_set_entry(p2m, start_gfn, nr, mfn, t, p2m->default_access);
+ p2m_write_unlock(p2m);
+
+ return rc;
+}
+
+int map_regions_p2mt(struct domain *d,
+ gfn_t gfn,
+ unsigned long nr,
+ mfn_t mfn,
+ p2m_type_t p2mt)
+{
+ return p2m_insert_mapping(d, gfn, nr, mfn, p2mt);
+}
What is this function doing here? The description says "for generic mapping
purposes", which really may mean anything. Plus, if and when you need it, it
wants to come with a name that fits with e.g. ...
These names are used across the common code and various architectures. Not all
architectures need to implement all of these functions.
I believe|guest_physmap_add_page()| (which internally
calls|guest_physmap_add_entry()|)
is needed to be implemented for all architectures, while|map_regions_p2mt()| is
used
by Arm and the common Dom0less-related code, and because of RISC-V is going to
re-use
common Dom0less code it is implementing this function too.
+int guest_physmap_add_entry(struct domain *d,
+ gfn_t gfn,
+ mfn_t mfn,
+ unsigned long page_order,
+ p2m_type_t t)
... this one, to understand their relationship / difference.
Basically, the difference is only in API and where they are expected to be used:
- guest_physmap_add_entry() to map and set a specific p2m type for a page.
- map_regions_p2mt() to map a region (mostly MMIO) in the guest p2m with
a specific p2m type.
I added both of them here as they are implemented in a similar way.
I will re-word commit subject and message:
xen/riscv: implement functions to map memory in guest p2m
Introduce guest_physmap_add_entry() to map a page and assign a specific
p2m type, and map_regions_p2mt() to map a region (typically MMIO) in
the guest p2m with a designated p2m type.
Currently, this functionality is not fully operational, as p2m_set_entry()
still returns -EOPNOTSUPP.
Additionally, introduce p2m_write_(un)lock() to protect modifications to
the p2m page tables, along with p2m TLB flush helpers to ensure proper
TLB invalidation (if necessary) when the p2m lock is released.
~ Oleksii
