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[xen master] xen/arm: Lookup bootinfo shm bank during the mapping



commit e90f8d562dd1aba59fa1e6835ed944b15b6d1931
Author:     Luca Fancellu <luca.fancellu@xxxxxxx>
AuthorDate: Fri May 24 13:40:49 2024 +0100
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Fri Jun 14 10:44:57 2024 +0100

    xen/arm: Lookup bootinfo shm bank during the mapping
    
    The current static shared memory code is using bootinfo banks when it
    needs to find the number of borrowers, so every time assign_shared_memory
    is called, the bank is searched in the bootinfo.shmem structure.
    
    There is nothing wrong with it, however the bank can be used also to
    retrieve the start address and size and also to pass less argument to
    assign_shared_memory. When retrieving the information from the bootinfo
    bank, it's also possible to move the checks on alignment to
    process_shm_node in the early stages.
    
    So create a new function find_shm_bank_by_id() which takes a
    'struct shared_meminfo' structure and the shared memory ID, to look for a
    bank with a matching ID, take the physical host address and size from the
    bank, pass the bank to assign_shared_memory() removing the now unnecessary
    arguments and finally remove the acquire_nr_borrower_domain() function
    since now the information can be extracted from the passed bank.
    Move the "xen,shm-id" parsing early in process_shm to bail out quickly in
    case of errors (unlikely), as said above, move the checks on alignment
    to process_shm_node.
    
    Drawback of this change is that now the bootinfo are used also when the
    bank doesn't need to be allocated, however it will be convenient later
    to use it as an argument for assign_shared_memory when dealing with
    the use case where the Host physical address is not supplied by the user.
    
    Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
    Reviewed-by: Michal Orzel <michal.orzel@xxxxxxx>
---
 xen/arch/arm/static-shmem.c | 100 +++++++++++++++++++++++---------------------
 1 file changed, 53 insertions(+), 47 deletions(-)

diff --git a/xen/arch/arm/static-shmem.c b/xen/arch/arm/static-shmem.c
index 78881dd1d3..0a1c327e90 100644
--- a/xen/arch/arm/static-shmem.c
+++ b/xen/arch/arm/static-shmem.c
@@ -19,29 +19,21 @@ static void __init __maybe_unused build_assertions(void)
                  offsetof(struct shared_meminfo, bank)));
 }
 
-static int __init acquire_nr_borrower_domain(struct domain *d,
-                                             paddr_t pbase, paddr_t psize,
-                                             unsigned long *nr_borrowers)
+static const struct membank __init *
+find_shm_bank_by_id(const struct membanks *shmem, const char *shm_id)
 {
-    const struct membanks *shmem = bootinfo_get_shmem();
     unsigned int bank;
 
-    /* Iterate reserved memory to find requested shm bank. */
     for ( bank = 0 ; bank < shmem->nr_banks; bank++ )
     {
-        paddr_t bank_start = shmem->bank[bank].start;
-        paddr_t bank_size = shmem->bank[bank].size;
-
-        if ( (pbase == bank_start) && (psize == bank_size) )
+        if ( strcmp(shm_id, shmem->bank[bank].shmem_extra->shm_id) == 0 )
             break;
     }
 
     if ( bank == shmem->nr_banks )
-        return -ENOENT;
+        return NULL;
 
-    *nr_borrowers = shmem->bank[bank].shmem_extra->nr_shm_borrowers;
-
-    return 0;
+    return &shmem->bank[bank];
 }
 
 /*
@@ -103,14 +95,18 @@ static mfn_t __init acquire_shared_memory_bank(struct 
domain *d,
     return smfn;
 }
 
-static int __init assign_shared_memory(struct domain *d,
-                                       paddr_t pbase, paddr_t psize,
-                                       paddr_t gbase)
+static int __init assign_shared_memory(struct domain *d, paddr_t gbase,
+                                       const struct membank *shm_bank)
 {
     mfn_t smfn;
     int ret = 0;
     unsigned long nr_pages, nr_borrowers, i;
     struct page_info *page;
+    paddr_t pbase, psize;
+
+    pbase = shm_bank->start;
+    psize = shm_bank->size;
+    nr_borrowers = shm_bank->shmem_extra->nr_shm_borrowers;
 
     printk("%pd: allocate static shared memory BANK 
%#"PRIpaddr"-%#"PRIpaddr".\n",
            d, pbase, pbase + psize);
@@ -135,14 +131,6 @@ static int __init assign_shared_memory(struct domain *d,
         }
     }
 
-    /*
-     * Get the right amount of references per page, which is the number of
-     * borrower domains.
-     */
-    ret = acquire_nr_borrower_domain(d, pbase, psize, &nr_borrowers);
-    if ( ret )
-        return ret;
-
     /*
      * Instead of letting borrower domain get a page ref, we add as many
      * additional reference as the number of borrowers when the owner
@@ -199,6 +187,7 @@ int __init process_shm(struct domain *d, struct kernel_info 
*kinfo,
 
     dt_for_each_child_node(node, shm_node)
     {
+        const struct membank *boot_shm_bank;
         const struct dt_property *prop;
         const __be32 *cells;
         uint32_t addr_cells, size_cells;
@@ -212,6 +201,23 @@ int __init process_shm(struct domain *d, struct 
kernel_info *kinfo,
         if ( !dt_device_is_compatible(shm_node, "xen,domain-shared-memory-v1") 
)
             continue;
 
+        if ( dt_property_read_string(shm_node, "xen,shm-id", &shm_id) )
+        {
+            printk("%pd: invalid \"xen,shm-id\" property", d);
+            return -EINVAL;
+        }
+        BUG_ON((strlen(shm_id) <= 0) || (strlen(shm_id) >= MAX_SHM_ID_LENGTH));
+
+        boot_shm_bank = find_shm_bank_by_id(bootinfo_get_shmem(), shm_id);
+        if ( !boot_shm_bank )
+        {
+            printk("%pd: static shared memory bank not found: '%s'", d, 
shm_id);
+            return -ENOENT;
+        }
+
+        pbase = boot_shm_bank->start;
+        psize = boot_shm_bank->size;
+
         /*
          * xen,shared-mem = <pbase, gbase, size>;
          * TODO: pbase is optional.
@@ -221,20 +227,7 @@ int __init process_shm(struct domain *d, struct 
kernel_info *kinfo,
         prop = dt_find_property(shm_node, "xen,shared-mem", NULL);
         BUG_ON(!prop);
         cells = (const __be32 *)prop->value;
-        device_tree_get_reg(&cells, addr_cells, addr_cells, &pbase, &gbase);
-        psize = dt_read_paddr(cells, size_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;
-        }
+        gbase = dt_read_paddr(cells + addr_cells, addr_cells);
 
         for ( i = 0; i < PFN_DOWN(psize); i++ )
             if ( !mfn_valid(mfn_add(maddr_to_mfn(pbase), i)) )
@@ -251,13 +244,6 @@ int __init process_shm(struct domain *d, struct 
kernel_info *kinfo,
         if ( dt_property_read_string(shm_node, "role", &role_str) == 0 )
             owner_dom_io = false;
 
-        if ( dt_property_read_string(shm_node, "xen,shm-id", &shm_id) )
-        {
-            printk("%pd: invalid \"xen,shm-id\" property", d);
-            return -EINVAL;
-        }
-        BUG_ON((strlen(shm_id) <= 0) || (strlen(shm_id) >= MAX_SHM_ID_LENGTH));
-
         /*
          * DOMID_IO is a fake domain and is not described in the Device-Tree.
          * Therefore when the owner of the shared region is DOMID_IO, we will
@@ -270,8 +256,8 @@ int __init process_shm(struct domain *d, struct kernel_info 
*kinfo,
              * We found the first borrower of the region, the owner was not
              * specified, so they should be assigned to dom_io.
              */
-            ret = assign_shared_memory(owner_dom_io ? dom_io : d,
-                                       pbase, psize, gbase);
+            ret = assign_shared_memory(owner_dom_io ? dom_io : d, gbase,
+                                       boot_shm_bank);
             if ( ret )
                 return ret;
         }
@@ -439,12 +425,32 @@ int __init process_shm_node(const void *fdt, int node, 
uint32_t address_cells,
     device_tree_get_reg(&cell, address_cells, address_cells, &paddr, &gaddr);
     size = dt_next_cell(size_cells, &cell);
 
+    if ( !IS_ALIGNED(paddr, PAGE_SIZE) )
+    {
+        printk("fdt: physical address 0x%"PRIpaddr" is not suitably 
aligned.\n",
+               paddr);
+        return -EINVAL;
+    }
+
+    if ( !IS_ALIGNED(gaddr, PAGE_SIZE) )
+    {
+        printk("fdt: guest address 0x%"PRIpaddr" is not suitably aligned.\n",
+               gaddr);
+        return -EINVAL;
+    }
+
     if ( !size )
     {
         printk("fdt: the size for static shared memory region can not be 
zero\n");
         return -EINVAL;
     }
 
+    if ( !IS_ALIGNED(size, PAGE_SIZE) )
+    {
+        printk("fdt: size 0x%"PRIpaddr" is not suitably aligned\n", size);
+        return -EINVAL;
+    }
+
     end = paddr + size;
     if ( end <= paddr )
     {
--
generated by git-patchbot for /home/xen/git/xen.git#master



 


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