[xen stable-4.21] xen/x86: Check supported features even for PVH dom0

[patchbot@xxxxxxx]

commit b2352be9415987e1d20281d8a9a8577600b417a4
Author:     Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
AuthorDate: Mon Apr 20 12:27:00 2026 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Apr 20 12:27:00 2026 +0200

    xen/x86: Check supported features even for PVH dom0
    
    The supported features ELF notes was tested only if the dom0 was
    PV. Factor out a function to check ELF notes and reuse it even
    for PVH.
    
    Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 44429b69319975f25d3762629b40fecdd4e3e554
    master date: 2026-04-09 21:04:58 +0100
---
 xen/arch/x86/dom0_build.c             | 12 ++++++++++++
 xen/arch/x86/hvm/dom0_build.c         |  3 +++
 xen/arch/x86/include/asm/dom0_build.h |  2 ++
 xen/arch/x86/pv/dom0_build.c          | 10 ++--------
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/dom0_build.c b/xen/arch/x86/dom0_build.c
index 0b467fd4a4..a32ad2739f 100644
--- a/xen/arch/x86/dom0_build.c
+++ b/xen/arch/x86/dom0_build.c
@@ -320,6 +320,18 @@ unsigned long __init dom0_paging_pages(const struct domain 
*d,
     return DIV_ROUND_UP(memkb, 1024) << (20 - PAGE_SHIFT);
 }
 
+int __init initdom_check_parms(
+    const struct domain *d, const struct elf_dom_parms *parms)
+{
+    if ( parms->elf_notes[XEN_ELFNOTE_SUPPORTED_FEATURES].type != XEN_ENT_NONE 
&&
+         is_hardware_domain(d) && !test_bit(XENFEAT_dom0, parms->f_supported) )
+    {
+        printk("Kernel does not support Dom0 operation\n");
+        return -EINVAL;
+    }
+
+    return 0;
+}
 
 /*
  * If allocation isn't specified, reserve 1/16th of available memory for
diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
index 6849e8c010..66199678e8 100644
--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -692,6 +692,9 @@ static int __init pvh_load_kernel(
         return -EINVAL;
     }
 
+    if ( (rc = initdom_check_parms(d, &parms)) != 0 )
+        return rc;
+
     /* Copy the OS image and free temporary buffer. */
     elf.dest_base = (void *)(parms.virt_kstart - parms.virt_base);
     elf.dest_size = parms.virt_kend - parms.virt_kstart;
diff --git a/xen/arch/x86/include/asm/dom0_build.h 
b/xen/arch/x86/include/asm/dom0_build.h
index ff021c24af..1332f18cc6 100644
--- a/xen/arch/x86/include/asm/dom0_build.h
+++ b/xen/arch/x86/include/asm/dom0_build.h
@@ -8,6 +8,8 @@
 
 extern unsigned int dom0_memflags;
 
+int initdom_check_parms(const struct domain *d,
+                        const struct elf_dom_parms *parms);
 unsigned long dom0_compute_nr_pages(struct domain *d,
                                     struct elf_dom_parms *parms,
                                     unsigned long initrd_len);
diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
index f9bbbea2ff..37729091df 100644
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -494,14 +494,8 @@ static int __init dom0_construct(const struct boot_domain 
*bd)
         return -EINVAL;
     }
 
-    if ( parms.elf_notes[XEN_ELFNOTE_SUPPORTED_FEATURES].type != XEN_ENT_NONE )
-    {
-        if ( !pv_shim && !test_bit(XENFEAT_dom0, parms.f_supported) )
-        {
-            printk("Kernel does not support Dom0 operation\n");
-            return -EINVAL;
-        }
-    }
+    if ( (rc = initdom_check_parms(d, &parms)) != 0 )
+        return rc;
 
     nr_pages = dom0_compute_nr_pages(d, &parms, initrd_len);
 
--
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