[PATCH v6 2/9] xen/arm: allocate static shared memory to the default owner dom_io

[Penny Zheng <Penny.Zheng@arm.com>]

From: Penny Zheng <penny.zheng@arm.com>

This commit introduces process_shm to cope with static shared memory in
domain construction.

DOMID_IO will be the default owner of memory pre-shared among multiple domains
at boot time, when no explicit owner is specified.

This commit only considers allocating static shared memory to dom_io
when owner domain is not explicitly defined in device tree, all the left,
including the "borrower" code path, the "explicit owner" code path, shall
be introduced later in the following patches.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
---
v6 change:
- use if-array to check psize, pbase and gbase are suitably aligned and
valid
- use mfn_valid to check (pbase, pbase + psize)
- check d->max_pages will not overflow
- refine acquire_shared_memory_bank to not reuse acquire_static_memory_bank,
then input pbase and psize do not need to be used as a pointer.
- use if-array to check if page owner is dom_io
- in-code comment refinement
---
v5 change:
- refine in-code comment
---
v4 change:
- no changes
---
v3 change:
- refine in-code comment
---
v2 change:
- instead of introducing a new system domain, reuse the existing dom_io
- make dom_io a non-auto-translated domain, then no need to create P2M
for it
- change dom_io definition and make it wider to support static shm here too
- introduce is_shm_allocated_to_domio to check whether static shm is
allocated yet, instead of using shm_mask bitmap
- add in-code comment
---
 xen/arch/arm/domain_build.c | 155 ++++++++++++++++++++++++++++++++++++
 xen/common/domain.c         |   3 +
 2 files changed, 158 insertions(+)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 3fd1186b53..ff2aebaf28 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -759,6 +759,155 @@ static void __init assign_static_memory_11(struct domain *d,
     panic("Failed to assign requested static memory for direct-map domain %pd.",
           d);
 }
+
+#ifdef CONFIG_STATIC_SHM
+/*
+ * This function checks whether the static shared memory region is
+ * already allocated to dom_io.
+ */
+static bool __init is_shm_allocated_to_domio(paddr_t pbase)
+{
+    struct page_info *page;
+
+    page = maddr_to_page(pbase);
+    if ( page_get_owner(page) == NULL )
+        return false;
+
+    if ( page_get_owner(page) != dom_io )
+    {
+        printk(XENLOG_ERR
+               "shm memory node has already been allocated to a specific owner %pd, Please check your configuration\n",
+               page_get_owner(page));
+        return false;
+    }
+
+    return true;
+}
+
+static mfn_t __init acquire_shared_memory_bank(struct domain *d,
+                                               paddr_t pbase, paddr_t psize)
+{
+    mfn_t smfn;
+    unsigned long nr_pfns;
+    int res;
+
+    /*
+     * Pages of statically shared memory shall be included
+     * into domain_tot_pages().
+     */
+    nr_pfns = PFN_DOWN(psize);
+    if ( (UINT_MAX - d->max_pages) < nr_pfns )
+    {
+        printk(XENLOG_ERR "%pd: Over-allocation for d->max_pages: %lu.\n",
+               d, nr_pfns);
+        return INVALID_MFN;
+    }
+    d->max_pages += nr_pfns;
+
+    smfn = maddr_to_mfn(pbase);
+    res = acquire_domstatic_pages(d, smfn, nr_pfns, 0);
+    if ( res )
+    {
+        printk(XENLOG_ERR
+               "%pd: failed to acquire static memory: %d.\n", d, res);
+        return INVALID_MFN;
+    }
+
+    return smfn;
+}
+
+static int __init allocate_shared_memory(struct domain *d,
+                                         u32 addr_cells, u32 size_cells,
+                                         paddr_t pbase, paddr_t psize)
+{
+    mfn_t smfn;
+
+    dprintk(XENLOG_INFO,
+            "%pd: allocate static shared memory BANK %#"PRIpaddr"-%#"PRIpaddr".\n",
+            d, pbase, pbase + psize);
+
+    smfn = acquire_shared_memory_bank(d, pbase, psize);
+    if ( mfn_eq(smfn, INVALID_MFN) )
+        return -EINVAL;
+
+    /*
+     * DOMID_IO is the domain, like DOMID_XEN, that is not auto-translated.
+     * It sees RAM 1:1 and we do not need to create P2M mapping for it
+     */
+    ASSERT(d == dom_io);
+    return 0;
+}
+
+static int __init process_shm(struct domain *d,
+                              const struct dt_device_node *node)
+{
+    struct dt_device_node *shm_node;
+
+    dt_for_each_child_node(node, shm_node)
+    {
+        const struct dt_property *prop;
+        const __be32 *cells;
+        uint32_t addr_cells, size_cells;
+        paddr_t gbase, pbase, psize;
+        int ret = 0;
+        unsigned int i;
+
+        if ( !dt_device_is_compatible(shm_node, "xen,domain-shared-memory-v1") )
+            continue;
+
+        /*
+         * xen,shared-mem = <pbase, psize, gbase>;
+         * TODO: pbase is optional.
+         */
+        addr_cells = dt_n_addr_cells(shm_node);
+        size_cells = dt_n_size_cells(shm_node);
+        prop = dt_find_property(shm_node, "xen,shared-mem", NULL);
+        ASSERT(prop);
+        cells = (const __be32 *)prop->value;
+        device_tree_get_reg(&cells, addr_cells, size_cells, &pbase, &psize);
+        gbase = dt_read_number(cells, addr_cells);
+        if ( !IS_ALIGNED(pbase, PAGE_SIZE) || !IS_ALIGNED(gbase, PAGE_SIZE) )
+        {
+            printk("%pd: physical address 0x%"PRIpaddr", or guest address 0x%"PRIpaddr" is not suitably aligned.\n",
+                   d, pbase, gbase);
+            return -EINVAL;
+        }
+        if ( !IS_ALIGNED(psize, PAGE_SIZE) )
+        {
+            printk("%pd: size 0x%"PRIpaddr" is not suitably aligned\n",
+                   d, psize);
+            return -EINVAL;
+        }
+
+        for ( i = 0; i < PFN_DOWN(psize); i++ )
+            if ( !mfn_valid(mfn_add(maddr_to_mfn(pbase), i)) )
+            {
+                printk("%pd: invalid physical address 0x%"PRI_mfn"\n",
+                       d, mfn_x(mfn_add(maddr_to_mfn(pbase), i)));
+                return -EINVAL;
+            }
+
+        /* TODO: Consider owner domain is not the default dom_io. */
+        /*
+         * Per static shared memory region could be shared between multiple
+         * domains.
+         * In case re-allocating the same shared memory region, we check
+         * if it is already allocated to the default owner dom_io before
+         * the actual allocation.
+         */
+        if ( !is_shm_allocated_to_domio(pbase) )
+        {
+            /* Allocate statically shared pages to the default owner dom_io. */
+            ret = allocate_shared_memory(dom_io, addr_cells, size_cells,
+                                         pbase, psize);
+            if ( ret )
+                return ret;
+        }
+    }
+
+    return 0;
+}
+#endif /* CONFIG_STATIC_SHM */
 #else
 static void __init allocate_static_memory(struct domain *d,
                                           struct kernel_info *kinfo,
@@ -3236,6 +3385,12 @@ static int __init construct_domU(struct domain *d,
     else
         assign_static_memory_11(d, &kinfo, node);
 
+#ifdef CONFIG_STATIC_SHM
+    rc = process_shm(d, node);
+    if ( rc < 0 )
+        return rc;
+#endif
+
     /*
      * Base address and irq number are needed when creating vpl011 device
      * tree node in prepare_dtb_domU, so initialization on related variables
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 618410e3b2..c8564113e9 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -780,6 +780,9 @@ void __init setup_system_domains(void)
      * This domain owns I/O pages that are within the range of the page_info
      * array. Mappings occur at the priv of the caller.
      * Quarantined PCI devices will be associated with this domain.
+     *
+     * DOMID_IO is also the default owner of memory pre-shared among multiple
+     * domains at boot time.
      */
     dom_io = domain_create(DOMID_IO, NULL, 0);
     if ( IS_ERR(dom_io) )
-- 
2.25.1