From: Julien Grall <julien@xen.org>
To: Penny Zheng <penny.zheng@arm.com>,
xen-devel@lists.xenproject.org, sstabellini@kernel.org
Cc: Bertrand.Marquis@arm.com, Wei.Chen@arm.com, nd@arm.com
Subject: Re: [PATCH V4 01/10] xen/arm: introduce domain on Static Allocation
Date: Wed, 11 Aug 2021 14:32:07 +0100 [thread overview]
Message-ID: <7c99d0dd-ef62-10a8-a11e-d2ca52910591@xen.org> (raw)
In-Reply-To: <20210728102758.3269446-2-penny.zheng@arm.com>
Hi Penny,
On 28/07/2021 11:27, Penny Zheng wrote:
> Static Allocation refers to system or sub-system(domains) for which memory
> areas are pre-defined by configuration using physical address ranges.
> Those pre-defined memory, -- Static Memory, as parts of RAM reserved in the
> beginning, shall never go to heap allocator or boot allocator for any use.
>
> Domains on Static Allocation is supported through device tree property
> `xen,static-mem` specifying reserved RAM banks as this domain's guest RAM.
> By default, they shall be mapped to the fixed guest RAM address
> `GUEST_RAM0_BASE`, `GUEST_RAM1_BASE`.
>
> This patch introduces this new `xen,static-mem` feature, and also documents
> and parses this new attribute at boot time and stores related info in
> static_mem for later initialization.
>
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> ---
> docs/misc/arm/device-tree/booting.txt | 40 +++++++++++++++++++++
> xen/arch/arm/bootfdt.c | 51 +++++++++++++++++++++++++++
> xen/include/asm-arm/setup.h | 2 ++
> 3 files changed, 93 insertions(+)
>
> diff --git a/docs/misc/arm/device-tree/booting.txt b/docs/misc/arm/device-tree/booting.txt
> index 5243bc7fd3..2a1ddca29b 100644
> --- a/docs/misc/arm/device-tree/booting.txt
> +++ b/docs/misc/arm/device-tree/booting.txt
> @@ -268,3 +268,43 @@ The DTB fragment is loaded at 0xc000000 in the example above. It should
> follow the convention explained in docs/misc/arm/passthrough.txt. The
> DTB fragment will be added to the guest device tree, so that the guest
> kernel will be able to discover the device.
> +
> +
> +Static Allocation
> +=============
> +
> +Static Allocation refers to system or sub-system(domains) for which memory
> +areas are pre-defined by configuration using physical address ranges.
> +Those pre-defined memory, -- Static Memory, as parts of RAM reserved in the
> +beginning, shall never go to heap allocator or boot allocator for any use.
I don't understand "as parts of RAM reserved in the beginning". Could
you clarify it?
> +
> +Domains on Static Allocation is supported through static memory property,
> +defined under according /domUx in the name of "xen,static-mem", which are
We don't require the domU node to be called /domUx.
> +specifying physical RAM as this domain's guest RAM.
>
How about:
Memory can be statically allocated to a domain using the property
"xen,static-mem" defined in the domain configuration.
> +The size of address-cells/size-cells must be defined in
I would say "The number of cells for the address and the size must be
defined using respectively the properties..."
> +"#xen,static-mem-address-cells" and "#xen,static-mem-size-cells".
> +
> +On memory allocation, these pre-defined static memory ranges shall be
> +firstly mapped to the fixed guest bank "GUEST_RAM0". Until it exhausts the
> +`GUEST_RAM0_SIZE`, then it will seek to `GUEST_RAM1_BASE`, and so on.
> +`GUEST_RAM0` may take up several pre-defined physical RAM regions.
GUEST_RAM0 & co are not part of the stable ABI. So I don't think the
documentation should mention them.
But I am not convinced we should provide a guarantee how the allocation
will happen. Why does it matter?
> +
> +The dtb property should look like as follows:
Do you mean "node" rather than "property"?
> +
> + / {
> + chosen {
> + domU1 {
> + compatible = "xen,domain";
> + #address-cells = <0x2>;
> + #size-cells = <0x2>;
> + cpus = <2>;
> + #xen,static-mem-address-cells = <0x1>;
> + #xen,static-mem-size-cells = <0x1>;
> + xen,static-mem = <0x30000000 0x20000000>;
> + ...
> + };
> + };
> + };
> +
> +DomU1 will have a static memory of 512MB reserved from the physical address
> +0x30000000 to 0x50000000.
I would write "This will reserve a 512MB region starting at the host
physical address 0x30000000 to be exclusively used by DomU1".
> diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
> index 476e32e0f5..d2714446e1 100644
> --- a/xen/arch/arm/bootfdt.c
> +++ b/xen/arch/arm/bootfdt.c
> @@ -193,6 +193,55 @@ static int __init process_reserved_memory_node(const void *fdt, int node,
> return 0;
> }
>
> +static int __init process_static_memory(const void *fdt, int node, void *data)
> +{
This is pretty much a copy of process_memory_node(). So can we avoid the
duplication?
I think I mentionned it in the past but I can't find the outcome.
> + int i = 0, banks;
> + const __be32 *cell;
> + paddr_t start, size;
> + u32 address_cells, size_cells, reg_cells;
> + struct meminfo *mem = data;
> + const struct fdt_property *prop;
> +
> +
> + address_cells = device_tree_get_u32(fdt, node,
> + "#xen,static-mem-address-cells", 0);
> + size_cells = device_tree_get_u32(fdt, node,
> + "#xen,static-mem-size-cells", 0);
> + if ( (address_cells == 0) || (size_cells == 0) )
> + {
> + printk("Missing \"#xen,static-mem-address-cell\" or "
> + "\"#xen,static-mem-address-cell\".\n");
> + return -EINVAL;
> + }
> + reg_cells = address_cells + size_cells;
> +
> + prop = fdt_get_property(fdt, node, "xen,static-mem", NULL);
> + /*
> + * Static memory shall belong to a specific domain, that is,
> + * its node `domUx` has compatible string "xen,domain".
> + */
This code is just checking the node compatible is "xen,domain". So I
would drop the "domUx". This is also...
> + if ( fdt_node_check_compatible(fdt, node, "xen,domain") != 0 )
> + {
> + printk("xen,static-mem property can only be located under /domUx node.\n");
... not correct.
> + return -EINVAL;
> + }
> +
> + cell = (const __be32 *)prop->data;
> + banks = fdt32_to_cpu(prop->len) / (reg_cells * sizeof (u32));
> +
> + for ( ; i < banks && mem->nr_banks < NR_MEM_BANKS; i++ )
> + {
> + device_tree_get_reg(&cell, address_cells, size_cells, &start, &size);
> + mem->bank[mem->nr_banks].start = start;
> + mem->bank[mem->nr_banks].size = size;
> + mem->nr_banks++;
> + }
> +
> + if ( i < banks )
> + return -ENOSPC;
> + return 0;
> +}
> +
> static int __init process_reserved_memory(const void *fdt, int node,
> const char *name, int depth,
> u32 address_cells, u32 size_cells)
> @@ -346,6 +395,8 @@ static int __init early_scan_node(const void *fdt,
> process_multiboot_node(fdt, node, name, address_cells, size_cells);
> else if ( depth == 1 && device_tree_node_matches(fdt, node, "chosen") )
> process_chosen_node(fdt, node, name, address_cells, size_cells);
> + else if ( depth == 2 && fdt_get_property(fdt, node, "xen,static-mem", NULL) )
How about checking the compatible instead?
> + process_static_memory(fdt, node, &bootinfo.static_mem);
You want "rc = ..." so the error is propaged if there is an issue (e.g.
we don't have space for more static region).
>
> if ( rc < 0 )
> printk("fdt: node `%s': parsing failed\n", name);
> diff --git a/xen/include/asm-arm/setup.h b/xen/include/asm-arm/setup.h
> index c4b6af6029..e076329fc4 100644
> --- a/xen/include/asm-arm/setup.h
> +++ b/xen/include/asm-arm/setup.h
> @@ -74,6 +74,8 @@ struct bootinfo {
> #ifdef CONFIG_ACPI
> struct meminfo acpi;
> #endif
> + /* Static Memory */
> + struct meminfo static_mem;
> };
>
> extern struct bootinfo bootinfo;
>
Cheers,
--
Julien Grall
next prev parent reply other threads:[~2021-08-11 13:32 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-28 10:27 [PATCH V4 00/10] Domain on Static Allocation Penny Zheng
2021-07-28 10:27 ` [PATCH V4 01/10] xen/arm: introduce domain " Penny Zheng
2021-08-11 13:32 ` Julien Grall [this message]
2021-08-16 5:21 ` Penny Zheng
2021-08-16 17:27 ` Julien Grall
2021-08-17 2:28 ` Penny Zheng
2021-07-28 10:27 ` [PATCH V4 02/10] xen/arm: introduce new helper device_tree_get_meminfo Penny Zheng
2021-08-11 13:35 ` Julien Grall
2021-08-16 5:27 ` Penny Zheng
2021-07-28 10:27 ` [PATCH V4 03/10] xen/arm: handle static memory in dt_unreserved_regions Penny Zheng
2021-08-11 13:48 ` Julien Grall
2021-08-16 6:00 ` Penny Zheng
2021-08-16 17:33 ` Julien Grall
2021-07-28 10:27 ` [PATCH V4 04/10] xen: introduce mark_page_free Penny Zheng
2021-08-11 14:08 ` Julien Grall
2021-07-28 10:27 ` [PATCH V4 05/10] xen/arm: static memory initialization Penny Zheng
2021-08-04 15:54 ` Jan Beulich
2021-08-13 12:20 ` Julien Grall
2021-08-16 6:12 ` Penny Zheng
2021-08-13 12:38 ` Julien Grall
2021-08-16 7:00 ` Wei Chen
2021-07-28 10:27 ` [PATCH V4 06/10] xen/arm: introduce PGC_reserved Penny Zheng
2021-08-13 12:21 ` Julien Grall
2021-08-16 6:13 ` Penny Zheng
2021-07-28 10:27 ` [PATCH V4 07/10] xen: re-define assign_pages and introduce assign_page Penny Zheng
2021-08-05 6:34 ` Jan Beulich
2021-08-13 12:27 ` Julien Grall
2021-08-13 12:32 ` Jan Beulich
2021-08-17 8:21 ` Penny Zheng
2021-07-28 10:27 ` [PATCH V4 08/10] xen/arm: introduce acquire_staticmem_pages and acquire_domstatic_pages Penny Zheng
2021-08-05 6:52 ` Jan Beulich
2021-08-13 13:00 ` Julien Grall
2021-08-16 6:43 ` Penny Zheng
2021-08-16 17:43 ` Julien Grall
2021-08-17 2:33 ` Penny Zheng
2021-07-28 10:27 ` [PATCH V4 09/10] xen/arm: check "xen,static-mem" property during domain construction Penny Zheng
2021-08-13 13:12 ` Julien Grall
2021-08-16 6:53 ` Penny Zheng
2021-07-28 10:27 ` [PATCH V4 10/10] xen/arm: introduce allocate_static_memory Penny Zheng
2021-08-13 13:36 ` Julien Grall
2021-08-16 7:51 ` Penny Zheng
2021-08-16 17:55 ` Julien Grall
2021-08-17 2:36 ` Penny Zheng
2021-07-28 10:27 ` [PATCH V4 04/10] xen: introduce mark_page_free Penny Zheng
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