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Re: [PATCH v2 5/5] xen/memory, tools: Make init-dom0less consume XEN_DOMCTL_get_mem_map


  • To: Jan Beulich <jbeulich@xxxxxxxx>
  • From: Henry Wang <xin.wang2@xxxxxxx>
  • Date: Tue, 12 Mar 2024 15:36:42 +0800
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  • Cc: Wei Liu <wl@xxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Alec Kwapis <alec.kwapis@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • Delivery-date: Tue, 12 Mar 2024 07:36:56 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

Hi Jan,

On 3/12/2024 3:34 PM, Jan Beulich wrote:
On 12.03.2024 04:44, Henry Wang wrote:
On 3/12/2024 1:07 AM, Jan Beulich wrote:
On 08.03.2024 02:54, Henry Wang wrote:
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -41,6 +41,11 @@
   #define XENMEMF_exact_node(n) (XENMEMF_node(n) | XENMEMF_exact_node_request)
   /* Flag to indicate the node specified is virtual node */
   #define XENMEMF_vnode  (1<<18)
+/*
+ * Flag to force populate physmap to use pages from domheap instead of 1:1
+ * or static allocation.
+ */
+#define XENMEMF_force_heap_alloc  (1<<19)
   #endif
If this is for populate_physmap only, then other sub-ops need to reject
its use.

I have to admit I'm a little wary of allocating another flag here and ...

--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -205,6 +205,8 @@ struct npfec {
   #define  MEMF_no_icache_flush (1U<<_MEMF_no_icache_flush)
   #define _MEMF_no_scrub    8
   #define  MEMF_no_scrub    (1U<<_MEMF_no_scrub)
+#define _MEMF_force_heap_alloc 9
+#define  MEMF_force_heap_alloc (1U<<_MEMF_force_heap_alloc)
   #define _MEMF_node        16
   #define  MEMF_node_mask   ((1U << (8 * sizeof(nodeid_t))) - 1)
   #define  MEMF_node(n)     ((((n) + 1) & MEMF_node_mask) << _MEMF_node)
... here - we don't have that many left. Since other sub-ops aren't
intended to support this flag, did you consider adding another (perhaps
even arch-specific) sub-op instead?
Not really, I basically followed the discussion from [1] to implement
this patch. However I understand your concern. Just want to make sure if
I understand your suggestion correctly, by "adding another sub-op" you
mean adding a sub-op similar as "XENMEM_populate_physmap" but only with
executing the "else" part I want, so we can drop the use of these two
added flags? Thanks!

[1]
https://lore.kernel.org/xen-devel/3982ba47-6709-47e3-a9c2-e2d3b4a2d8e3@xxxxxxx/
In which case please check with Julien (and perhaps other Arm maintainers)
before deciding on whether to go this alternative route.

Yes sure, I will wait a bit longer for the agreement of the discussion before implementing the code.

Kind regards,
Henry

Jan




 


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