From: Penny Zheng <Penny.Zheng@arm.com>
To: Julien Grall <julien@xen.org>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"sstabellini@kernel.org" <sstabellini@kernel.org>
Cc: Bertrand Marquis <Bertrand.Marquis@arm.com>,
Wei Chen <Wei.Chen@arm.com>, nd <nd@arm.com>
Subject: RE: [PATCH V4 01/10] xen/arm: introduce domain on Static Allocation
Date: Mon, 16 Aug 2021 05:21:37 +0000 [thread overview]
Message-ID: <VE1PR08MB521506FADC3CC8096D9B98DFF7FD9@VE1PR08MB5215.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <7c99d0dd-ef62-10a8-a11e-d2ca52910591@xen.org>
Hi Julien
> -----Original Message-----
> From: Julien Grall <julien@xen.org>
> Sent: Wednesday, August 11, 2021 9:32 PM
> To: Penny Zheng <Penny.Zheng@arm.com>; xen-devel@lists.xenproject.org;
> sstabellini@kernel.org
> Cc: Bertrand Marquis <Bertrand.Marquis@arm.com>; Wei Chen
> <Wei.Chen@arm.com>; nd <nd@arm.com>
> Subject: Re: [PATCH V4 01/10] xen/arm: introduce domain on Static Allocation
>
> 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?
>
I mean, static memory is very alike reserved memory, reserved during system boot time,
not dynamically allocated at runtime.
> > +
> > +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.
>
Oh, thx for explanation. I will take domU node instead.
> > +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..."
>
Sure. Thx for the rephrasing.
> > +"#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?
>
Yeah, I put it here to be in comparison with the later 1:1 direct-map, however, it is truly not
part of the stable ABI, so I will delete it in documentation here,
> > +
> > +The dtb property should look like as follows:
>
> Do you mean "node" rather than "property"?
>
Oh, sure. Maybe "as an example" shall be more clarified.
> > + 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".
>
Sure, thx.
> > 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.
>
I checked it here, to make sure the "xen,static-mem" property must be used in a domain node, since
for now, static memory could be only configured as guest RAM.
Which part do you think it is not appropriate here?
> > + 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?
>
hmm, since it is a property, not a node. so...
> > + 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).
>
Yes, my neglect. I'll make sure the error get propagated here.
> >
> > 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,
>
> --
Cheers
Penny
> Julien Grall
next prev parent reply other threads:[~2021-08-16 5:22 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
2021-08-16 5:21 ` Penny Zheng [this message]
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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