Re: [PATCH v2 0/10] iomem memory policy

[Oleksandr <olekstysh@gmail.com>]

On 01.05.19 00:02, Stefano Stabellini wrote:
> Hi all,

Hi, Stefano


>
> This series introduces a memory policy parameter for the iomem option,
> so that we can map an iomem region into a guest as cacheable memory.
>
> Then, this series fixes the way Xen handles reserved memory regions on
> ARM: they should be mapped as normal memory, instead today they are
> treated as device memory.
>
> Cheers,
>
> Stefano
>
>
>
> The following changes since commit be3d5b30331d87e177744dbe23138b9ebcdc86f1:
>
>    x86/msr: Fix fallout from mostly c/s 832c180 (2019-04-15 17:51:30 +0100)
>
> are available in the git repository at:
>
>    http://xenbits.xenproject.org/git-http/people/sstabellini/xen-unstable.git iomem_cache-v2
>
> for you to fetch changes up to 4979f8e2f1120b2c394be815b071c017e287cf33:
>
>    xen/arm: add reserved-memory regions to the dom0 memory node (2019-04-30 13:56:40 -0700)
>
> ----------------------------------------------------------------
> Stefano Stabellini (10):
>        xen: add a p2mt parameter to map_mmio_regions
>        xen: rename un/map_mmio_regions to un/map_regions
>        xen: extend XEN_DOMCTL_memory_mapping to handle memory policy
>        libxc: introduce xc_domain_mem_map_policy
>        libxl/xl: add memory policy option to iomem
>        xen/arm: extend device_tree_for_each_node
>        xen/arm: make process_memory_node a device_tree_node_func
>        xen/arm: keep track of reserved-memory regions
>        xen/arm: map reserved-memory regions as normal memory in dom0
>        xen/arm: add reserved-memory regions to the dom0 memory node

Thank you for doing that. Support of reserved-memory in Xen on ARM is a 
quite important feature. We are interested in possibility to provide 
reserved-memory regions to DomU. Our system uses *thin Dom0* which 
doesn't have H/W IPs assigned which may require reserved-memory, unlike, 
other domains which could have. So, I would be happy to test your patch 
series on R-Car Gen3 platforms if you have a plan to extend this support 
for covering other than hwdom domains. There are a few quite different 
reserved-memory regions used in Renesas BSP, I think, it would be a good 
target to test on...

https://git.kernel.org/pub/scm/linux/kernel/git/horms/renesas-bsp.git/tree/arch/arm64/boot/dts/renesas/r8a7795-salvator-x.dts#n37 


As for the current series, I have tested Xen boot only. Looks like, 
*real* reserved-memory regions were handled correctly, but some test 
"non-reserved-memory" node was interpreted as a "reserved-memory" and 
was taken into the account... Please see details below.

--------------------
Host device tree contains the following nodes:

memory@48000000 {
     device_type = "memory";
     /* first 128MB is reserved for secure area. */
     reg = <0x0 0x48000000 0x0 0x78000000>,
           <0x5 0x00000000 0x0 0x80000000>,
           <0x6 0x00000000 0x0 0x80000000>,
           <0x7 0x00000000 0x0 0x80000000>;
};

reserved-memory {
     #address-cells = <2>;
     #size-cells = <2>;
     ranges;

     /* device specific region for Lossy Decompression */
     lossy_decompress: linux,lossy_decompress@54000000 {
         no-map;
         reg = <0x00000000 0x54000000 0x0 0x03000000>;
     };

     /* For Audio DSP */
     adsp_reserved: linux,adsp@57000000 {
         compatible = "shared-dma-pool";
         reusable;
         reg = <0x00000000 0x57000000 0x0 0x01000000>;
     };

     /* global autoconfigured region for contiguous allocations */
     linux,cma@58000000 {
         compatible = "shared-dma-pool";
         reusable;
         reg = <0x00000000 0x58000000 0x0 0x18000000>;
         linux,cma-default;
     };

     /* device specific region for contiguous allocations */
     mmp_reserved: linux,multimedia@70000000 {
         compatible = "shared-dma-pool";
         reusable;
         reg = <0x00000000 0x70000000 0x0 0x10000000>;
     };
};

/* test "non-reserved-memory" node */
sram: sram@47FFF000 {
     compatible = "mmio-sram";
     reg = <0x0 0x47FFF000 0x0 0x1000>;

     #address-cells = <1>;
     #size-cells = <1>;
     ranges = <0 0x0 0x47FFF000 0x1000>;

     scp_shmem: scp_shmem@0 {
         compatible = "mmio-sram";
         reg = <0x0 0x200>;
     };
};

--------------------

I added a print to see which memory regions were inserted:

diff --git a/xen/arch/arm/bootfdt.c b/xen/arch/arm/bootfdt.c
index 9355a6e..23e68b0 100644
--- a/xen/arch/arm/bootfdt.c
+++ b/xen/arch/arm/bootfdt.c
@@ -162,6 +162,10 @@ static int __init process_memory_node(const void 
*fdt, int node,
          device_tree_get_reg(&cell, address_cells, size_cells, &start, 
&size);
          if ( !size )
              continue;
+
+        dt_dprintk("node %s: insert bank %d: %#"PRIx64"->%#"PRIx64" 
type: %s\n",
+                   name, i, start, start + size, reserved ? "reserved" 
: "normal");
+
          mem->bank[mem->nr_banks].start = start;
          mem->bank[mem->nr_banks].size = size;
          mem->nr_banks++;

--------------------

Xen log shows that test "non-reserved-memory" node (scp_shmem@0) is 
processed as "reserved-memory":

(XEN) Checking for initrd in /chosen
(XEN) Initrd 0000000076000040-0000000077c87e47
(XEN) node memory@48000000: insert bank 0: 0x48000000->0xc0000000 type: 
normal
(XEN) node memory@48000000: insert bank 1: 0x500000000->0x580000000 
type: normal
(XEN) node memory@48000000: insert bank 2: 0x600000000->0x680000000 
type: normal
(XEN) node memory@48000000: insert bank 3: 0x700000000->0x780000000 
type: normal
(XEN) node linux,lossy_decompress@54000000: insert bank 0: 
0x54000000->0x57000000 type: reserved
(XEN) node linux,adsp@57000000: insert bank 0: 0x57000000->0x58000000 
type: reserved
(XEN) node linux,cma@58000000: insert bank 0: 0x58000000->0x70000000 
type: reserved
(XEN) node linux,multimedia@70000000: insert bank 0: 
0x70000000->0x80000000 type: reserved
(XEN) node scp_shmem@0: insert bank 0: 0->0x200 type: reserved   
<----------- test "non-reserved-memory" node
(XEN) RAM: 0000000048000000 - 00000000bfffffff
(XEN) RAM: 0000000500000000 - 000000057fffffff
(XEN) RAM: 0000000600000000 - 000000067fffffff
(XEN) RAM: 0000000700000000 - 000000077fffffff
(XEN)
(XEN) MODULE[0]: 0000000048000000 - 0000000048014080 Device Tree
(XEN) MODULE[1]: 0000000076000040 - 0000000077c87e47 Ramdisk
(XEN) MODULE[2]: 000000007a000000 - 000000007c000000 Kernel
(XEN) MODULE[3]: 000000007c000000 - 000000007c010000 XSM
(XEN)  RESVD[0]: 0000000048000000 - 0000000048014000
(XEN)  RESVD[1]: 0000000076000040 - 0000000077c87e47

...

(XEN) handle /memory@48000000
(XEN)   Skip it (matched)
(XEN) handle /reserved-memory
(XEN) dt_irq_number: dev=/reserved-memory
(XEN) /reserved-memory passthrough = 1 nirq = 0 naddr = 0
(XEN) handle /reserved-memory/linux,lossy_decompress@54000000
(XEN) dt_irq_number: dev=/reserved-memory/linux,lossy_decompress@54000000
(XEN) /reserved-memory/linux,lossy_decompress@54000000 passthrough = 1 
nirq = 0 naddr = 1
(XEN) DT: ** translation for device 
/reserved-memory/linux,lossy_decompress@54000000 **
(XEN) DT: bus is default (na=2, ns=2) on /reserved-memory
(XEN) DT: translating address:<3> 00000000<3> 54000000<3>
(XEN) DT: parent bus is default (na=2, ns=2) on /
(XEN) DT: empty ranges; 1:1 translation
(XEN) DT: parent translation for:<3> 00000000<3> 00000000<3>
(XEN) DT: with offset: 54000000
(XEN) DT: one level translation:<3> 00000000<3> 54000000<3>
(XEN) DT: reached root node
(XEN)   - MMIO: 0054000000 - 0057000000 P2MType=5
(XEN) handle /reserved-memory/linux,adsp@57000000
(XEN) dt_irq_number: dev=/reserved-memory/linux,adsp@57000000
(XEN) /reserved-memory/linux,adsp@57000000 passthrough = 1 nirq = 0 
naddr = 1
(XEN) DT: ** translation for device /reserved-memory/linux,adsp@57000000 **
(XEN) DT: bus is default (na=2, ns=2) on /reserved-memory
(XEN) DT: translating address:<3> 00000000<3> 57000000<3>
(XEN) DT: parent bus is default (na=2, ns=2) on /
(XEN) DT: empty ranges; 1:1 translation
(XEN) DT: parent translation for:<3> 00000000<3> 00000000<3>
(XEN) DT: with offset: 57000000
(XEN) DT: one level translation:<3> 00000000<3> 57000000<3>
(XEN) DT: reached root node
(XEN)   - MMIO: 0057000000 - 0058000000 P2MType=5
(XEN) handle /reserved-memory/linux,cma@58000000
(XEN) dt_irq_number: dev=/reserved-memory/linux,cma@58000000
(XEN) /reserved-memory/linux,cma@58000000 passthrough = 1 nirq = 0 naddr = 1
(XEN) DT: ** translation for device /reserved-memory/linux,cma@58000000 **
(XEN) DT: bus is default (na=2, ns=2) on /reserved-memory
(XEN) DT: translating address:<3> 00000000<3> 58000000<3>
(XEN) DT: parent bus is default (na=2, ns=2) on /
(XEN) DT: empty ranges; 1:1 translation
(XEN) DT: parent translation for:<3> 00000000<3> 00000000<3>
(XEN) DT: with offset: 58000000
(XEN) DT: one level translation:<3> 00000000<3> 58000000<3>
(XEN) DT: reached root node
(XEN)   - MMIO: 0058000000 - 0070000000 P2MType=5
(XEN) handle /reserved-memory/linux,multimedia@70000000
(XEN) dt_irq_number: dev=/reserved-memory/linux,multimedia@70000000
(XEN) /reserved-memory/linux,multimedia@70000000 passthrough = 1 nirq = 
0 naddr = 1
(XEN) DT: ** translation for device 
/reserved-memory/linux,multimedia@70000000 **
(XEN) DT: bus is default (na=2, ns=2) on /reserved-memory
(XEN) DT: translating address:<3> 00000000<3> 70000000<3>
(XEN) DT: parent bus is default (na=2, ns=2) on /
(XEN) DT: empty ranges; 1:1 translation
(XEN) DT: parent translation for:<3> 00000000<3> 00000000<3>
(XEN) DT: with offset: 70000000
(XEN) DT: one level translation:<3> 00000000<3> 70000000<3>
(XEN) DT: reached root node
(XEN)   - MMIO: 0070000000 - 0080000000 P2MType=5

...


(XEN) Create memory node (reg size 4, nr cells 24)
(XEN)   Bank 0: 0xb0000000->0xc0000000   <----------- Dom0 memory which 
is 256MB total
(XEN)   Bank 0: 0x54000000->0x57000000   <----------- 
linux,lossy_decompress@54000000
(XEN)   Bank 1: 0x57000000->0x58000000   <----------- linux,adsp@57000000
(XEN)   Bank 2: 0x58000000->0x70000000   <----------- linux,cma@58000000
(XEN)   Bank 3: 0x70000000->0x80000000   <----------- 
linux,multimedia@70000000
(XEN)   Bank 4: 0->0x200   <----------- test "non-reserved-memory" node
(XEN) Loading zImage from 000000007a000000 to 
00000000b0080000-00000000b2080000
(XEN) Loading dom0 initrd from 0000000076000040 to 
0x00000000b8200000-0x00000000b9e87e07
(XEN) Loading dom0 DTB to 0x00000000b8000000-0x00000000b8011b7f
(XEN) Initial low memory virq threshold set at 0x4000 pages.
(XEN) Std. Loglevel: All
(XEN) Guest Loglevel: All

...


-- 
Regards,

Oleksandr Tyshchenko


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