[xen master] xen/dom0less: Clear xenstore page

[patchbot@xxxxxxx]

commit 76f9dbf9a2ffaeb0fed8661232d628dbffcfd333
Author:     Jason Andryuk <jason.andryuk@xxxxxxx>
AuthorDate: Wed Aug 20 17:12:42 2025 -0400
Commit:     Michal Orzel <michal.orzel@xxxxxxx>
CommitDate: Fri Aug 22 09:56:51 2025 +0200

    xen/dom0less: Clear xenstore page
    
    C Xenstored was seen failing to map a domU's event channel.  Enhancing
    Xen's error messages shows:
    common/event_channel.c:427:d0v0 EVTCHNOP failure: d1, port 3267543746 error 
-22
    
    Port 3267543746 is 0xc2c2c2c2 - SCRUB_PATTERN.
    
    Xenstore expects a non-zero evtchn_port to be valid.  Explicitly zero
    the page to avoid this.
    
    Fixes: df2c03e2ebfe ("xen/arm: Alloc XenStore page for Dom0less DomUs from 
hypervisor")
    Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
    Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
    Acked-by: Michal Orzel <michal.orzel@xxxxxxx>
---
 xen/common/device-tree/dom0less-build.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/xen/common/device-tree/dom0less-build.c 
b/xen/common/device-tree/dom0less-build.c
index 6bb038111d..badc227031 100644
--- a/xen/common/device-tree/dom0less-build.c
+++ b/xen/common/device-tree/dom0less-build.c
@@ -600,6 +600,7 @@ static int __init alloc_xenstore_page(struct domain *d)
     d->arch.hvm.params[HVM_PARAM_STORE_PFN] = gfn_x(gfn);
 #endif
     interface = map_domain_page(mfn);
+    clear_page(interface);
     interface->connection = XENSTORE_RECONNECT;
     unmap_domain_page(interface);
 
--
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