Implement the p2m_next_level() function, which enables traversal and dynamic
allocation of intermediate levels (if necessary) in the RISC-V
p2m (physical-to-machine) page table hierarchy.
To support this, the following helpers are introduced:
- page_to_p2m_table(): Constructs non-leaf PTEs pointing to next-level page
tables with correct attributes.
- p2m_alloc_page(): Allocates page table pages, supporting both hardware and
guest domains.
- p2m_create_table(): Allocates and initializes a new page table page and
installs it into the hierarchy.
Signed-off-by: Oleksii Kurochko <oleksii.kuroc...@gmail.com>
---
Changes in V3:
- s/p2me_is_mapping/p2m_is_mapping to be in syc with other p2m_is_*()
functions.
- clear_and_clean_page() in p2m_create_table() instead of clear_page() to be
sure that page is cleared and d-cache is flushed for it.
- Move ASSERT(level != 0) in p2m_next_level() ahead of trying to allocate a
page table.
- Update p2m_create_table() to allocate metadata page to store p2m type in it
for each entry of page table.
- Introduce paging_alloc_page() and use it inside p2m_alloc_page().
- Add allocated page to p2m->pages list in p2m_alloc_page() to simplify
a caller code a little bit.
- Drop p2m_is_mapping() and use pte_is_mapping() instead as P2M PTE's valid
bit doesn't have another purpose anymore.
- Update an implementation and prototype of page_to_p2m_table(), it is enough
to pass only a page as an argument.
---
Changes in V2:
- New patch. It was a part of a big patch "xen/riscv: implement p2m mapping
functionality" which was splitted to smaller.
- s/p2m_is_mapping/p2m_is_mapping.
---
xen/arch/riscv/include/asm/paging.h | 2 +
xen/arch/riscv/p2m.c | 80 ++++++++++++++++++++++++++++-
xen/arch/riscv/paging.c | 11 ++++
3 files changed, 91 insertions(+), 2 deletions(-)
diff --git a/xen/arch/riscv/include/asm/paging.h
b/xen/arch/riscv/include/asm/paging.h
index c9063b7f76..3642bcfc7a 100644
--- a/xen/arch/riscv/include/asm/paging.h
+++ b/xen/arch/riscv/include/asm/paging.h
@@ -14,4 +14,6 @@ bool paging_ret_pages_to_domheap(struct domain *d, unsigned
int nr_pages);
void paging_free_page(struct domain *d, struct page_info *pg);
+struct page_info * paging_alloc_page(struct domain *d);
+
#endif /* ASM_RISCV_PAGING_H */
diff --git a/xen/arch/riscv/p2m.c b/xen/arch/riscv/p2m.c
index efc7320619..e04cfde8c7 100644
--- a/xen/arch/riscv/p2m.c
+++ b/xen/arch/riscv/p2m.c
@@ -302,6 +302,48 @@ static pte_t p2m_pte_from_mfn(mfn_t mfn, p2m_type_t t,
bool is_table)
return e;
}
+/* Generate table entry with correct attributes. */
+static pte_t page_to_p2m_table(struct page_info *page)
+{
+ /*
+ * p2m_invalid will be ignored inside p2m_pte_from_mfn() as is_table is
+ * set to true and p2m_type_t shouldn't be applied for PTEs which
+ * describe an intermidiate table.
+ */
+ return p2m_pte_from_mfn(page_to_mfn(page), p2m_invalid, true);
+}
+
+static struct page_info *p2m_alloc_page(struct p2m_domain *p2m)
+{
+ struct page_info *pg = paging_alloc_page(p2m->domain);
+
+ if ( pg )
+ page_list_add(pg, &p2m->pages);
+
+ return pg;
+}
+
+/*
+ * Allocate a new page table page with an extra metadata page and hook it
+ * in via the given entry.
+ */
+static int p2m_create_table(struct p2m_domain *p2m, pte_t *entry)
+{
+ struct page_info *page;
+
+ ASSERT(!pte_is_valid(*entry));
+
+ page = p2m_alloc_page(p2m);
+ if ( page == NULL )
+ return -ENOMEM;
+
+ clear_and_clean_page(page);
+
+ p2m_write_pte(entry, page_to_p2m_table(page), p2m->clean_pte);
+
+ return 0;
+}
+
#define P2M_TABLE_MAP_NONE 0
#define P2M_TABLE_MAP_NOMEM 1
#define P2M_TABLE_SUPER_PAGE 2
@@ -326,9 +368,43 @@ static int p2m_next_level(struct p2m_domain *p2m, bool
alloc_tbl,
unsigned int level, pte_t **table,
unsigned int offset)
{
- panic("%s: hasn't been implemented yet\n", __func__);
+ pte_t *entry;
+ int ret;
+ mfn_t mfn;
+
+ /* The function p2m_next_level() is never called at the last level */
+ ASSERT(level != 0);
+
+ entry = *table + offset;
+
+ if ( !pte_is_valid(*entry) )
+ {
+ if ( !alloc_tbl )
+ return P2M_TABLE_MAP_NONE;
+
+ ret = p2m_create_table(p2m, entry);
+ if ( ret )
+ return P2M_TABLE_MAP_NOMEM;
+ }
+
+ /* The function p2m_next_level() is never called at the last level */
+ ASSERT(level != 0);
+ if ( pte_is_mapping(*entry) )
+ return P2M_TABLE_SUPER_PAGE;
+
+ mfn = mfn_from_pte(*entry);
+
+ unmap_domain_page(*table);
+
+ /*
+ * TODO: There's an inefficiency here:
+ * In p2m_create_table(), the page is mapped to clear it.
+ * Then that mapping is torn down in p2m_create_table(),
+ * only to be re-established here.
+ */
+ *table = map_domain_page(mfn);
- return P2M_TABLE_MAP_NONE;
+ return P2M_TABLE_NORMAL;
}
static void p2m_put_foreign_page(struct page_info *pg)
diff --git a/xen/arch/riscv/paging.c b/xen/arch/riscv/paging.c
index 853e0e14c6..72ff183260 100644
--- a/xen/arch/riscv/paging.c
+++ b/xen/arch/riscv/paging.c
@@ -91,6 +91,17 @@ void paging_free_page(struct domain *d, struct page_info *pg)
spin_unlock(&d->arch.paging.lock);
}
+struct page_info * paging_alloc_page(struct domain *d)
+{
+ struct page_info *pg;
+
+ spin_lock(&d->arch.paging.lock);
+ pg = page_list_remove_head(&d->arch.paging.freelist);
+ spin_unlock(&d->arch.paging.lock);
+
+ return pg;
+}
+
/* Domain paging struct initialization. */
int paging_domain_init(struct domain *d)
{
--
2.50.1
