Hi,
> On 8 Sep 2022, at 22:05, Stefano Stabellini <sstabell...@kernel.org> wrote:
>
> On Thu, 8 Sep 2022, Penny Zheng wrote:
>> We expose the shared memory to the domU using the "xen,shared-memory-v1"
>> reserved-memory binding. See
>> Documentation/devicetree/bindings/reserved-memory/xen,shared-memory.txt
>> in Linux for the corresponding device tree binding.
>>
>> To save the cost of re-parsing shared memory device tree configuration when
>> creating shared memory nodes in guest device tree, this commit adds new field
>> "shm_mem" to store shm-info per domain.
>>
>> For each shared memory region, a range is exposed under
>> the /reserved-memory node as a child node. Each range sub-node is
>> named xen-shmem@<address> and has the following properties:
>> - compatible:
>> compatible = "xen,shared-memory-v1"
>> - reg:
>> the base guest physical address and size of the shared memory region
>> - xen,id:
>> a string that identifies the shared memory region.
>> - xen,offset: (borrower VMs only)
>> 64 bit integer offset within the owner virtual machine's shared
>> memory region used for the mapping in the borrower VM.
>> Currently, we provide "xen,offset=<0x0>" as a temprary placeholder.
> ^ temporary
>
> Another minor style issue below
>
>
>> Signed-off-by: Penny Zheng <penny.zh...@arm.com>
>> Reviewed-by: Stefano Stabellini <sstabell...@kernel.org>
>> ---
>> v8 changes:
>> - Fix missing property "xen,offset" for borrower VMs by temporarily
>> adding "xen,offset=<0x0>"
>> - use >= to avoid thinking about the overflow case for nr_banks
>> - check the return value of dt_property_read_string() for parsing
>> shm_id
>> - struct meminfo *mem and char resvbuf[16] = "reserved-memory" could be
>> const
>> - change "__be32 reg[4]" to "__be32 reg[GUEST_ROOT_ADDRESS_CELLS +
>> GUEST_ROOT_SIZE_CELLS]"
>> ---
>> v7 changes:
>> - allocate reg for worst case addrcells + sizecells
>> - replace assert() with BUG_ON() since it is init code
>> ---
>> v6 change:
>> - change "struct meminfo *mem" to "const struct meminfo *mem"
>> - change "unsigned long i" to "unsigned int i" to match the type of nr_banks.
>> - accroding to the Linux binding, "xen,id" is meant to be a string, not
>> an integer
>> ---
>> v5 change:
>> - no change
>> ---
>> v4 change:
>> - no change
>> ---
>> v3 change:
>> - move field "shm_mem" to kernel_info
>> ---
>> v2 change:
>> - using xzalloc
>> - shm_id should be uint8_t
>> - make reg a local variable
>> - add #address-cells and #size-cells properties
>> - fix alignment
>> ---
>> xen/arch/arm/domain_build.c | 160 +++++++++++++++++++++++++++++-
>> xen/arch/arm/include/asm/kernel.h | 1 +
>> 2 files changed, 159 insertions(+), 2 deletions(-)
>>
>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>> index a10d07266b..cd03370b38 100644
>> --- a/xen/arch/arm/domain_build.c
>> +++ b/xen/arch/arm/domain_build.c
>> @@ -914,7 +914,22 @@ static int __init assign_shared_memory(struct domain *d,
>> return ret;
>> }
>>
>> -static int __init process_shm(struct domain *d,
>> +static int __init append_shm_bank_to_domain(struct kernel_info *kinfo,
>> + paddr_t start, paddr_t size,
>> + const char *shm_id)
>> +{
>> + if ( kinfo->shm_mem.nr_banks >= NR_MEM_BANKS )
>> + return -ENOMEM;
>> +
>> + kinfo->shm_mem.bank[kinfo->shm_mem.nr_banks].start = start;
>> + kinfo->shm_mem.bank[kinfo->shm_mem.nr_banks].size = size;
>> + safe_strcpy(kinfo->shm_mem.bank[kinfo->shm_mem.nr_banks].shm_id,
>> shm_id);
>> + kinfo->shm_mem.nr_banks++;
>> +
>> + return 0;
>> +}
>> +
>> +static int __init process_shm(struct domain *d, struct kernel_info *kinfo,
>> const struct dt_device_node *node)
>> {
>> struct dt_device_node *shm_node;
>> @@ -928,6 +943,7 @@ static int __init process_shm(struct domain *d,
>> int ret = 0;
>> unsigned int i;
>> const char *role_str;
>> + const char *shm_id;
>> bool owner_dom_io = true;
>>
>> if ( !dt_device_is_compatible(shm_node,
>> "xen,domain-shared-memory-v1") )
>> @@ -972,6 +988,13 @@ static int __init process_shm(struct domain *d,
>> 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
>> @@ -999,6 +1022,14 @@ static int __init process_shm(struct domain *d,
>> if ( ret )
>> return ret;
>> }
>> +
>> + /*
>> + * Record static shared memory region info for later setting
>> + * up shm-node in guest device tree.
>> + */
>> + ret = append_shm_bank_to_domain(kinfo, gbase, psize, shm_id);
>> + if ( ret )
>> + return ret;
>> }
>>
>> return 0;
>> @@ -1331,6 +1362,126 @@ static int __init make_memory_node(const struct
>> domain *d,
>> return res;
>> }
>>
>> +#ifdef CONFIG_STATIC_SHM
>> +static int __init make_shm_memory_node(const struct domain *d,
>> + void *fdt,
>> + int addrcells, int sizecells,
>> + const struct meminfo *mem)
>> +{
>> + unsigned int i = 0;
>> + int res = 0;
>> +
>> + if ( mem->nr_banks == 0 )
>> + return -ENOENT;
>> +
>> + /*
>> + * For each shared memory region, a range is exposed under
>> + * the /reserved-memory node as a child node. Each range sub-node is
>> + * named xen-shmem@<address>.
>> + */
>> + dt_dprintk("Create xen-shmem node\n");
>> +
>> + for ( ; i < mem->nr_banks; i++ )
>> + {
>> + uint64_t start = mem->bank[i].start;
>> + uint64_t size = mem->bank[i].size;
>> + /* Placeholder for xen-shmem@ + a 64-bit number + \0 */
>> + char buf[27];
>> + const char compat[] = "xen,shared-memory-v1";
>> + /* Worst case addrcells + sizecells */
>> + __be32 reg[GUEST_ROOT_ADDRESS_CELLS + GUEST_ROOT_SIZE_CELLS];
>> + __be32 *cells;
>> + unsigned int len = (addrcells + sizecells) * sizeof(__be32);
>> +
>> + snprintf(buf, sizeof(buf), "xen-shmem@%"PRIx64, mem->bank[i].start);
>> + res = fdt_begin_node(fdt, buf);
>> + if ( res )
>> + return res;
>> +
>> + res = fdt_property(fdt, "compatible", compat, sizeof(compat));
>> + if ( res )
>> + return res;
>> +
>> + cells = reg;
>> + dt_child_set_range(&cells, addrcells, sizecells, start, size);
>> +
>> + res = fdt_property(fdt, "reg", reg, len);
>> + if ( res )
>> + return res;
>> +
>> + dt_dprintk("Shared memory bank %u: %#"PRIx64"->%#"PRIx64"\n",
>> + i, start, start + size);
>> +
>> + res = fdt_property_string(fdt, "xen,id", mem->bank[i].shm_id);
>> + if ( res )
>> + return res;
>> +
>> + /* TODO:
>
> It should be:
>
> /*
> * TODO:
> *
>
> I think this is good to go. The two minor style issues could be fixed on
> commit. I haven't committed to give Julien & Bertrand another chance to
> have a look.
I think that it is ok to fix those on commit and I am ok with the rest so:
Reviewed-by: Bertrand Marquis <bertrand.marq...@arm.com>
Cheers
Bertrand
>
>
>
>> + * - xen,offset: (borrower VMs only)
>> + * 64 bit integer offset within the owner virtual machine's shared
>> + * memory region used for the mapping in the borrower VM
>> + */
>> + res = fdt_property_u64(fdt, "xen,offset", 0);
>> + if ( res )
>> + return res;
>> +
>> + res = fdt_end_node(fdt);
>> + if ( res )
>> + return res;
>> + }
>> +
>> + return res;
>> +}
>> +#else
>> +static int __init make_shm_memory_node(const struct domain *d,
>> + void *fdt,
>> + int addrcells, int sizecells,
>> + const struct meminfo *mem)
>> +{
>> + ASSERT_UNREACHABLE();
>> +}
>> +#endif
>> +
>> +static int __init make_resv_memory_node(const struct domain *d,
>> + void *fdt,
>> + int addrcells, int sizecells,
>> + const struct meminfo *mem)
>> +{
>> + int res = 0;
>> + /* Placeholder for reserved-memory\0 */
>> + const char resvbuf[16] = "reserved-memory";
>> +
>> + if ( mem->nr_banks == 0 )
>> + /* No shared memory provided. */
>> + return 0;
>> +
>> + dt_dprintk("Create reserved-memory node\n");
>> +
>> + res = fdt_begin_node(fdt, resvbuf);
>> + if ( res )
>> + return res;
>> +
>> + res = fdt_property(fdt, "ranges", NULL, 0);
>> + if ( res )
>> + return res;
>> +
>> + res = fdt_property_cell(fdt, "#address-cells", addrcells);
>> + if ( res )
>> + return res;
>> +
>> + res = fdt_property_cell(fdt, "#size-cells", sizecells);
>> + if ( res )
>> + return res;
>> +
>> + res = make_shm_memory_node(d, fdt, addrcells, sizecells, mem);
>> + if ( res )
>> + return res;
>> +
>> + res = fdt_end_node(fdt);
>> +
>> + return res;
>> +}
>> +
>> static int __init add_ext_regions(unsigned long s, unsigned long e, void
>> *data)
>> {
>> struct meminfo *ext_regions = data;
>> @@ -3108,6 +3259,11 @@ static int __init prepare_dtb_domU(struct domain *d,
>> struct kernel_info *kinfo)
>> if ( ret )
>> goto err;
>>
>> + ret = make_resv_memory_node(d, kinfo->fdt, addrcells, sizecells,
>> + &kinfo->shm_mem);
>> + if ( ret )
>> + goto err;
>> +
>> /*
>> * domain_handle_dtb_bootmodule has to be called before the rest of
>> * the device tree is generated because it depends on the value of
>> @@ -3484,7 +3640,7 @@ static int __init construct_domU(struct domain *d,
>> assign_static_memory_11(d, &kinfo, node);
>>
>> #ifdef CONFIG_STATIC_SHM
>> - rc = process_shm(d, node);
>> + rc = process_shm(d, &kinfo, node);
>> if ( rc < 0 )
>> return rc;
>> #endif
>> diff --git a/xen/arch/arm/include/asm/kernel.h
>> b/xen/arch/arm/include/asm/kernel.h
>> index c4dc039b54..2cc506b100 100644
>> --- a/xen/arch/arm/include/asm/kernel.h
>> +++ b/xen/arch/arm/include/asm/kernel.h
>> @@ -19,6 +19,7 @@ struct kernel_info {
>> void *fdt; /* flat device tree */
>> paddr_t unassigned_mem; /* RAM not (yet) assigned to a bank */
>> struct meminfo mem;
>> + struct meminfo shm_mem;
>>
>> /* kernel entry point */
>> paddr_t entry;
>> --
>> 2.25.1
