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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v3 1/8] xen/arm: introduce static shared memory
From: Penny Zheng <penny.zheng@xxxxxxx>
This patch serie 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>
---
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 | 120 ++++++++++++++++++++++++++
xen/arch/arm/Kconfig | 6 ++
xen/arch/arm/bootfdt.c | 68 +++++++++++++++
xen/arch/arm/include/asm/setup.h | 3 +
4 files changed, 197 insertions(+)
diff --git a/docs/misc/arm/device-tree/booting.txt
b/docs/misc/arm/device-tree/booting.txt
index a94125394e..e63ce171fc 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -355,3 +355,123 @@ 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 u8 value represents the unique identifier of the shared memory region.
+ The maximum identifier shall be "xen,shm-id = <0xff>".
+
+- 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. 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.
+
+- 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
+ "dom_shared", 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 = <0x0>;
+ 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 = <0x0>;
+ xen,shared-mem = <0x10000000 0x10000000 0x50000000>;
+ }
+
+ /*
+ * 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 = <0x1>;
+ xen,shared-mem = <0x50000000 0x20000000 0x60000000>;
+ }
+
+ ......
+
+ };
+
+ 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 = <0x1>;
+ xen,shared-mem = <0x50000000 0x20000000 0x70000000>;
+ }
+
+ ......
+ };
+};
+
+This is an example with two static shared memory regions.
+
+For the static shared memory region identified as 0x0, 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 0x1, 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 dom_shared.
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index ecfa6822e4..5ee9921f56 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -106,6 +106,12 @@ 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 29671c8df0..c8e8747c3e 100644
--- a/xen/arch/arm/bootfdt.c
+++ b/xen/arch/arm/bootfdt.c
@@ -360,6 +360,70 @@ 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,
+ u32 address_cells, u32 size_cells)
+{
+ const struct fdt_property *prop;
+ const __be32 *cell;
+ paddr_t paddr, size;
+ struct meminfo *mem = &bootinfo.reserved_mem;
+ unsigned long i;
+
+ if ( address_cells < 1 || size_cells < 1 )
+ {
+ printk("fdt: invalid #address-cells or #size-cells for static shared
memory node.\n");
+ return -EINVAL;
+ }
+
+ prop = fdt_get_property(fdt, node, "xen,shared-mem", NULL);
+ if ( !prop )
+ return -ENOENT;
+
+ /*
+ * xen,shared-mem = <paddr, size, gaddr>;
+ * Memory region starting from physical address #paddr of #size shall
+ * be mapped to guest physical address #gaddr as static shared memory
+ * region.
+ */
+ cell = (const __be32 *)prop->data;
+ device_tree_get_reg(&cell, address_cells, size_cells, &paddr, &size);
+ for ( i = 0; i < mem->nr_banks; i++ )
+ {
+ /*
+ * A static shared memory region could be shared between multiple
+ * domains.
+ */
+ if ( paddr == mem->bank[i].start && size == mem->bank[i].size )
+ break;
+ }
+
+ if ( i == mem->nr_banks )
+ {
+ if ( i < NR_MEM_BANKS )
+ {
+ /* Static shared memory shall be reserved from any other use. */
+ 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 domains, which later may be used to
+ * calculate the number of the reference count.
+ */
+ mem->bank[i].nr_shm_domain++;
+
+ return 0;
+}
+#endif
+
static int __init early_scan_node(const void *fdt,
int node, const char *name, int depth,
u32 address_cells, u32 size_cells,
@@ -380,6 +444,10 @@ 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);
+#ifdef CONFIG_STATIC_SHM
+ 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);
+#endif
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 7a1e1d6798..35449bd7d8 100644
--- a/xen/arch/arm/include/asm/setup.h
+++ b/xen/arch/arm/include/asm/setup.h
@@ -27,6 +27,9 @@ 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
+ unsigned int nr_shm_domain;
+#endif
};
struct meminfo {
--
2.25.1
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