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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v7 1/9] xen/arm: introduce static shared memory
From: Penny Zheng <penny.zheng@xxxxxxx>
This patch series introduces a new feature: setting up static
shared memory on a dom0less system, through device tree configuration.
This commit parses shared memory node at boot-time, and reserve it in
bootinfo.reserved_mem to avoid other use.
This commits proposes a new Kconfig CONFIG_STATIC_SHM to wrap
static-shm-related codes, and this option depends on static memory(
CONFIG_STATIC_MEMORY). That's because that later we want to reuse a few
helpers, guarded with CONFIG_STATIC_MEMORY, like acquire_staticmem_pages, etc,
on static shared memory.
Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
---
v7 change:
- add docs about checking for region overlap, etc
- update docs to reflect that the host physical address is optional
- end/bank_end may end up to be lower than paddr/mem->bank[i].start, So check
that they don't overflow.
- replace strcmp with strncmp since the string has already be validated
- provide a dummy helper for process_shm_node() when !CONFIG_STATIC_SHM
- remove useless #ifdef CONFIG_STATIC_SHM
- change the order of property xen,shared-mem to
xen,shared-mem = < [host physical address] [guest address] [size] >
---
v6 change:
- when host physical address is ommited, output the error message since
xen doesn't support it at the moment
- add the following check: 1) The shm ID matches and the region exactly match
2) The shm ID doesn't match and the region doesn't overlap
- change it to "unsigned int" to be aligned with nr_banks
- check the len of the property to confirm is it big enough to
contain "paddr", "size", and "gaddr"
- shm_id defined before nr_shm_domain, so we could re-use the existing hole and
avoid increasing the size of the structure.
- change "nr_shm_domain" to "nr_shm_borrowers", to not increment if the role
is owner in parsing code
- make "xen,shm_id" property as arbitrary string, with a strict limit on
the number of characters, MAX_SHM_ID_LENGTH
---
v5 change:
- no change
---
v4 change:
- nit fix on doc
---
v3 change:
- make nr_shm_domain unsigned int
---
v2 change:
- document refinement
- remove bitmap and use the iteration to check
- add a new field nr_shm_domain to keep the number of shared domain
---
docs/misc/arm/device-tree/booting.txt | 132 +++++++++++++++++++++
xen/arch/arm/Kconfig | 6 +
xen/arch/arm/bootfdt.c | 165 ++++++++++++++++++++++++++
xen/arch/arm/include/asm/setup.h | 7 ++
4 files changed, 310 insertions(+)
diff --git a/docs/misc/arm/device-tree/booting.txt
b/docs/misc/arm/device-tree/booting.txt
index 98253414b8..1c50fc6351 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -378,3 +378,135 @@ device-tree:
This will reserve a 512MB region starting at the host physical address
0x30000000 to be exclusively used by DomU1.
+
+Static Shared Memory
+====================
+
+The static shared memory device tree nodes allow users to statically set up
+shared memory on dom0less system, enabling domains to do shm-based
+communication.
+
+- compatible
+
+ "xen,domain-shared-memory-v1"
+
+- xen,shm-id
+
+ An arbitrary string that represents the unique identifier of the shared
+ memory region, with a strict limit on the number of characters(\0
included),
+ `MAX_SHM_ID_LENGTH(16)`. e.g. "xen,shm-id = "my-shared-mem-1"".
+
+- xen,shared-mem
+
+ An array takes a physical address, which is the base address of the
+ shared memory region in host physical address space, a size, and a guest
+ physical address, as the target address of the mapping.
+ e.g. xen,shared-mem = < [host physical address] [guest address] [size] >
+
+ It shall also meet the following criteria:
+ 1) If the SHM ID matches with an existing region, the address range of the
+ region shall also exactly match.
+ 2) If the SHM ID does not match with any other existing region, it should
+ also not overlap with any other regions.
+
+ The number of cells for the host address (and size) is the same as the
+ guest pseudo-physical address and they are inherited from the parent node.
+
+ Host physical address is optional, when missing Xen decides the location
+ (currently unimplemented).
+
+- role (Optional)
+
+ A string property specifying the ownership of a shared memory region,
+ the value must be one of the following: "owner", or "borrower"
+ A shared memory region could be explicitly backed by one domain, which is
+ called "owner domain", and all the other domains who are also sharing
+ this region are called "borrower domain".
+ If not specified, the default value is "borrower" and owner is
+ DOMID_IO, a system domain.
+
+As an example:
+
+chosen {
+ #address-cells = <0x1>;
+ #size-cells = <0x1>;
+ xen,xen-bootargs = "console=dtuart dtuart=serial0 bootscrub=0";
+
+ ......
+
+ /* this is for Dom0 */
+ dom0-shared-mem@10000000 {
+ compatible = "xen,domain-shared-memory-v1";
+ role = "owner";
+ xen,shm-id = "my-shared-mem-0";
+ xen,shared-mem = <0x10000000 0x10000000 0x10000000>;
+ }
+
+ domU1 {
+ compatible = "xen,domain";
+ #address-cells = <0x1>;
+ #size-cells = <0x1>;
+ memory = <0 131072>;
+ cpus = <2>;
+ vpl011;
+
+ /*
+ * shared memory region identified as 0x0(xen,shm-id = <0x0>)
+ * is shared between Dom0 and DomU1.
+ */
+ domU1-shared-mem@10000000 {
+ compatible = "xen,domain-shared-memory-v1";
+ role = "borrower";
+ xen,shm-id = "my-shared-mem-0";
+ xen,shared-mem = <0x10000000 0x50000000 0x10000000>;
+ }
+
+ /*
+ * shared memory region identified as 0x1(xen,shm-id = <0x1>)
+ * is shared between DomU1 and DomU2.
+ */
+ domU1-shared-mem@50000000 {
+ compatible = "xen,domain-shared-memory-v1";
+ xen,shm-id = "my-shared-mem-1";
+ xen,shared-mem = <0x50000000 0x60000000 0x20000000>;
+ }
+
+ ......
+
+ };
+
+ domU2 {
+ compatible = "xen,domain";
+ #address-cells = <0x1>;
+ #size-cells = <0x1>;
+ memory = <0 65536>;
+ cpus = <1>;
+
+ /*
+ * shared memory region identified as 0x1(xen,shm-id = <0x1>)
+ * is shared between domU1 and domU2.
+ */
+ domU2-shared-mem@50000000 {
+ compatible = "xen,domain-shared-memory-v1";
+ xen,shm-id = "my-shared-mem-1";
+ xen,shared-mem = <0x50000000 0x70000000 0x20000000>;
+ }
+
+ ......
+ };
+};
+
+This is an example with two static shared memory regions.
+
+For the static shared memory region identified as "my-shared-mem-0", host
+physical address starting at 0x10000000 of 256MB will be reserved to be
+shared between Dom0 and DomU1. It will get mapped at 0x10000000 in Dom0 guest
+physical address space, and at 0x50000000 in DomU1 guest physical address
space.
+Dom0 is explicitly defined as the owner domain, and DomU1 is the borrower
domain.
+
+For the static shared memory region identified as "my-shared-mem-1", host
+physical address starting at 0x50000000 of 512MB will be reserved to be
+shared between DomU1 and DomU2. It will get mapped at 0x60000000 in DomU1 guest
+physical address space, and at 0x70000000 in DomU2 guest physical address
space.
+DomU1 and DomU2 are both the borrower domain, the owner domain is the default
+owner domain DOMID_IO.
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index 33e004d702..1fe5faf847 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -140,6 +140,12 @@ config TEE
source "arch/arm/tee/Kconfig"
+config STATIC_SHM
+ bool "Statically shared memory on a dom0less system" if UNSUPPORTED
+ depends on STATIC_MEMORY
+ help
+ This option enables statically shared memory on a dom0less system.
+
endmenu
menu "ARM errata workaround via the alternative framework"
diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
index ec81a45de9..b2cd425dac 100644
--- a/xen/arch/arm/bootfdt.c
+++ b/xen/arch/arm/bootfdt.c
@@ -13,6 +13,7 @@
#include <xen/init.h>
#include <xen/efi.h>
#include <xen/device_tree.h>
+#include <xen/lib.h>
#include <xen/libfdt/libfdt.h>
#include <xen/sort.h>
#include <xsm/xsm.h>
@@ -361,6 +362,168 @@ static int __init process_domain_node(const void *fdt,
int node,
size_cells, &bootinfo.reserved_mem, true);
}
+#ifdef CONFIG_STATIC_SHM
+static int __init process_shm_node(const void *fdt, int node,
+ uint32_t address_cells, uint32_t size_cells)
+{
+ const struct fdt_property *prop, *prop_id, *prop_role;
+ const __be32 *cell;
+ paddr_t paddr, gaddr, size;
+ struct meminfo *mem = &bootinfo.reserved_mem;
+ unsigned int i;
+ int len;
+ bool owner = false;
+ const char *shm_id;
+
+ if ( address_cells < 1 || size_cells < 1 )
+ {
+ printk("fdt: invalid #address-cells or #size-cells for static shared
memory node.\n");
+ return -EINVAL;
+ }
+
+ /*
+ * "xen,shm-id" property holds an arbitrary string with a strict limit
+ * on the number of characters, MAX_SHM_ID_LENGTH
+ */
+ prop_id = fdt_get_property(fdt, node, "xen,shm-id", NULL);
+ if ( !prop_id )
+ return -ENOENT;
+ shm_id = (const char *)prop_id->data;
+ if ( strnlen(shm_id, MAX_SHM_ID_LENGTH) == MAX_SHM_ID_LENGTH )
+ {
+ printk("fdt: invalid xen,shm-id %s, it must be limited to %u
characters\n",
+ shm_id, MAX_SHM_ID_LENGTH);
+ return -EINVAL;
+ }
+
+ /*
+ * "role" property is optional and if it is defined explicitly,
+ * it must be either `owner` or `borrower`.
+ */
+ prop_role = fdt_get_property(fdt, node, "role", NULL);
+ if ( prop_role )
+ {
+ if ( !strcmp(prop_role->data, "owner") )
+ owner = true;
+ else if ( strcmp(prop_role->data, "borrower") )
+ {
+ printk("fdt: invalid `role` property for static shared memory
node.\n");
+ return -EINVAL;
+ }
+ }
+
+ /*
+ * xen,shared-mem = <paddr, gaddr, size>;
+ * Memory region starting from physical address #paddr of #size shall
+ * be mapped to guest physical address #gaddr as static shared memory
+ * region.
+ */
+ prop = fdt_get_property(fdt, node, "xen,shared-mem", &len);
+ if ( !prop )
+ return -ENOENT;
+
+ if ( len != dt_cells_to_size(address_cells + size_cells + address_cells) )
+ {
+ if ( len == dt_cells_to_size(size_cells + address_cells) )
+ printk("fdt: host physical address must be chosen by users at the
moment.\n");
+
+ printk("fdt: invalid `xen,shared-mem` property.\n");
+ return -EINVAL;
+ }
+
+ cell = (const __be32 *)prop->data;
+ device_tree_get_reg(&cell, address_cells, address_cells, &paddr, &gaddr);
+ size = dt_next_cell(size_cells, &cell);
+
+ if ( !size )
+ {
+ printk("fdt: the size for static shared memory region can not be
zero\n");
+ return -EINVAL;
+ }
+
+ for ( i = 0; i < mem->nr_banks; i++ )
+ {
+ /*
+ * Meet the following check:
+ * 1) The shm ID matches and the region exactly match
+ * 2) The shm ID doesn't match and the region doesn't overlap
+ * with an existing one
+ */
+ if ( paddr == mem->bank[i].start && size == mem->bank[i].size )
+ {
+ if ( strncmp(shm_id, mem->bank[i].shm_id, MAX_SHM_ID_LENGTH) == 0 )
+ break;
+ else
+ {
+ printk("fdt: xen,shm-id %s does not match for all the nodes
using the same region.\n",
+ shm_id);
+ return -EINVAL;
+ }
+ }
+ else
+ {
+ paddr_t end = paddr + size;
+ paddr_t bank_end = mem->bank[i].start + mem->bank[i].size;
+
+ if ( (end <= paddr) || (bank_end <= mem->bank[i].start) )
+ printk("fdt: static shared memory region %s overflow\n",
shm_id);
+
+ if ( (end <= mem->bank[i].start) || (paddr >= bank_end) )
+ {
+ if ( strcmp(shm_id, mem->bank[i].shm_id) != 0 )
+ continue;
+ else
+ {
+ printk("fdt: different shared memory region could not
share the same shm ID %s\n",
+ shm_id);
+ return -EINVAL;
+ }
+ }
+ else
+ {
+ printk("fdt: shared memory region overlap with an existing
entry %#"PRIpaddr" - %#"PRIpaddr"\n",
+ mem->bank[i].start, bank_end);
+ return -EINVAL;
+ }
+ }
+ }
+
+ if ( i == mem->nr_banks )
+ {
+ if ( i < NR_MEM_BANKS )
+ {
+ /* Static shared memory shall be reserved from any other use. */
+ safe_strcpy(mem->bank[mem->nr_banks].shm_id, shm_id);
+ mem->bank[mem->nr_banks].start = paddr;
+ mem->bank[mem->nr_banks].size = size;
+ mem->bank[mem->nr_banks].xen_domain = true;
+ mem->nr_banks++;
+ }
+ else
+ {
+ printk("Warning: Max number of supported memory regions
reached.\n");
+ return -ENOSPC;
+ }
+ }
+ /*
+ * keep a count of the number of borrowers, which later may be used
+ * to calculate the reference count.
+ */
+ if ( !owner )
+ mem->bank[i].nr_shm_borrowers++;
+
+ return 0;
+}
+#else
+static int __init process_shm_node(const void *fdt, int node,
+ uint32_t address_cells, uint32_t size_cells)
+{
+ printk("CONFIG_STATIC_SHM must be enabled for parsing static shared memory
nodes\n");
+ WARN();
+ return -EINVAL;
+}
+#endif
+
static int __init early_scan_node(const void *fdt,
int node, const char *name, int depth,
u32 address_cells, u32 size_cells,
@@ -386,6 +549,8 @@ static int __init early_scan_node(const void *fdt,
process_chosen_node(fdt, node, name, address_cells, size_cells);
else if ( depth == 2 && device_tree_node_compatible(fdt, node,
"xen,domain") )
rc = process_domain_node(fdt, node, name, address_cells, size_cells);
+ else if ( depth <= 3 && device_tree_node_compatible(fdt, node,
"xen,domain-shared-memory-v1") )
+ rc = process_shm_node(fdt, node, address_cells, size_cells);
if ( rc < 0 )
printk("fdt: node `%s': parsing failed\n", name);
diff --git a/xen/arch/arm/include/asm/setup.h b/xen/arch/arm/include/asm/setup.h
index 5815ccf8c5..995eee1d09 100644
--- a/xen/arch/arm/include/asm/setup.h
+++ b/xen/arch/arm/include/asm/setup.h
@@ -23,10 +23,17 @@ typedef enum {
} bootmodule_kind;
+/* Indicates the maximum number of characters(\0 included) for shm_id */
+#define MAX_SHM_ID_LENGTH 16
+
struct membank {
paddr_t start;
paddr_t size;
bool xen_domain; /* whether the memory bank is bound to a Xen domain. */
+#ifdef CONFIG_STATIC_SHM
+ char shm_id[MAX_SHM_ID_LENGTH];
+ unsigned int nr_shm_borrowers;
+#endif
};
struct meminfo {
--
2.25.1
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