[Xen-devel] [PATCH v3 10/38] arm/p2m: Move hostp2m init/teardown to individual functions

[Sergej Proskurin <proskurin@xxxxxxxxxxxxx>]

This commit pulls out generic init/teardown functionality out of
"p2m_init" and "p2m_teardown" into "p2m_init_one", "p2m_teardown_one",
and "p2m_flush_table" functions.  This allows our future implementation
to reuse existing code for the initialization/teardown of altp2m views.

Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx>
---
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
---
v2: Added the function p2m_flush_table to the previous version.

v3: Removed struct vttbr.

    Moved define INVALID_VTTBR to p2m.h.

    Exported function prototypes of "p2m_flush_table", "p2m_init_one",
    and "p2m_teardown_one" in p2m.h.

    Extended the function "p2m_flush_table" by additionally resetting
    the fields lowest_mapped_gfn and max_mapped_gfn.

    Added a "p2m_flush_tlb" call in "p2m_flush_table". On altp2m reset
    in function "altp2m_reset", it is important to flush the TLBs after
    clearing the root table pages and before clearing the intermediate
    altp2m page tables to prevent illegal access to stalled TLB entries
    on currently active VCPUs.

    Added a check checking whether p2m->root is NULL in p2m_flush_table.

    Renamed the function "p2m_free_one" to "p2m_teardown_one".

    Removed resetting p2m->vttbr in "p2m_teardown_one", as it the p2m
    will be destroyed afterwards.

    Moved call to "p2m_alloc_table" back to "p2m_init_one".

    Moved the introduction of the type p2m_class_t out of this patch.

    Moved the backpointer to the struct domain out of the struct
    p2m_domain.
---
 xen/arch/arm/p2m.c        | 71 +++++++++++++++++++++++++++++++++++++++++------
 xen/include/asm-arm/p2m.h | 11 ++++++++
 2 files changed, 73 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index e859fca..9ef19d4 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -1245,27 +1245,53 @@ static void p2m_free_vmid(struct domain *d)
     spin_unlock(&vmid_alloc_lock);
 }
 
-void p2m_teardown(struct domain *d)
+/* Reset this p2m table to be empty. */
+void p2m_flush_table(struct p2m_domain *p2m)
 {
-    struct p2m_domain *p2m = p2m_get_hostp2m(d);
-    struct page_info *pg;
+    struct page_info *page, *pg;
+    unsigned int i;
+
+    if ( p2m->root )
+    {
+        page = p2m->root;
+
+        /* Clear all concatenated first level pages. */
+        for ( i = 0; i < P2M_ROOT_PAGES; i++ )
+            clear_and_clean_page(page + i);
+    }
+
+    /*
+     * Flush TLBs before releasing remaining intermediate p2m page tables to
+     * prevent illegal access to stalled TLB entries.
+     */
+    p2m_flush_tlb(p2m);
 
+    /* Free the rest of the trie pages back to the paging pool. */
     while ( (pg = page_list_remove_head(&p2m->pages)) )
         free_domheap_page(pg);
 
+    p2m->lowest_mapped_gfn = INVALID_GFN;
+    p2m->max_mapped_gfn = _gfn(0);
+}
+
+void p2m_teardown_one(struct p2m_domain *p2m)
+{
+    p2m_flush_table(p2m);
+
     if ( p2m->root )
         free_domheap_pages(p2m->root, P2M_ROOT_ORDER);
 
     p2m->root = NULL;
 
-    p2m_free_vmid(d);
+    p2m_free_vmid(p2m->domain);
+
+    p2m->vttbr = INVALID_VTTBR;
 
     radix_tree_destroy(&p2m->mem_access_settings, NULL);
 }
 
-int p2m_init(struct domain *d)
+int p2m_init_one(struct domain *d, struct p2m_domain *p2m)
 {
-    struct p2m_domain *p2m = p2m_get_hostp2m(d);
     int rc = 0;
 
     rwlock_init(&p2m->lock);
@@ -1278,11 +1304,14 @@ int p2m_init(struct domain *d)
         return rc;
 
     p2m->max_mapped_gfn = _gfn(0);
-    p2m->lowest_mapped_gfn = _gfn(ULONG_MAX);
+    p2m->lowest_mapped_gfn = INVALID_GFN;
 
     p2m->domain = d;
+    p2m->access_required = false;
     p2m->default_access = p2m_access_rwx;
     p2m->mem_access_enabled = false;
+    p2m->root = NULL;
+    p2m->vttbr = INVALID_VTTBR;
     radix_tree_init(&p2m->mem_access_settings);
 
     /*
@@ -1293,9 +1322,33 @@ int p2m_init(struct domain *d)
     p2m->clean_pte = iommu_enabled &&
         !iommu_has_feature(d, IOMMU_FEAT_COHERENT_WALK);
 
-    rc = p2m_alloc_table(d);
+    return p2m_alloc_table(d);
+}
 
-    return rc;
+static void p2m_teardown_hostp2m(struct domain *d)
+{
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    p2m_teardown_one(p2m);
+}
+
+void p2m_teardown(struct domain *d)
+{
+    p2m_teardown_hostp2m(d);
+}
+
+static int p2m_init_hostp2m(struct domain *d)
+{
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    p2m->p2m_class = p2m_host;
+
+    return p2m_init_one(d, p2m);
+}
+
+int p2m_init(struct domain *d)
+{
+    return p2m_init_hostp2m(d);
 }
 
 /*
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index fa07e19..1a004ed 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -11,6 +11,8 @@
 
 #define paddr_bits PADDR_BITS
 
+#define INVALID_VTTBR (0UL)
+
 /* Holds the bit size of IPAs in p2m tables.  */
 extern unsigned int p2m_ipa_bits;
 
@@ -226,6 +228,15 @@ void guest_physmap_remove_page(struct domain *d,
 
 mfn_t gfn_to_mfn(struct domain *d, gfn_t gfn);
 
+/* Flushes the page table held by the p2m. */
+void p2m_flush_table(struct p2m_domain *p2m);
+
+/* Initialize the p2m structure. */
+int p2m_init_one(struct domain *d, struct p2m_domain *p2m);
+
+/* Release resources held by the p2m structure. */
+void p2m_teardown_one(struct p2m_domain *p2m);
+
 /*
  * P2M rwlock helpers.
  */
-- 
2.9.0


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