xen: branch for v5.9-rc9

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Merge tag 'for-linus-5.9b-rc9-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fix from Juergen Gross:
 "One fix for a regression when booting as a Xen guest on ARM64
  introduced probably during the 5.9 cycle. It is very low risk as it is
  modifying Xen specific code only.

  The exact commit introducing the bug hasn't been identified yet, but
  everything was fine in 5.8 and only in 5.9 some configurations started
  to fail"

* tag 'for-linus-5.9b-rc9-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  arm/arm64: xen: Fix to convert percpu address to gfn correctly

arch/arm/xen/enlighten.c

@@ -150,7 +150,7 @@ static int xen_starting_cpu(unsigned int cpu)
 	pr_info("Xen: initializing cpu%d\n", cpu);
 	vcpup = per_cpu_ptr(xen_vcpu_info, cpu);
 
-	info.mfn = virt_to_gfn(vcpup);
+	info.mfn = percpu_to_gfn(vcpup);
 	info.offset = xen_offset_in_page(vcpup);
 
 	err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, xen_vcpu_nr(cpu),

include/xen/arm/page.h

@@ -83,6 +83,9 @@ static inline unsigned long bfn_to_pfn(unsigned long bfn)
 	})
 #define gfn_to_virt(m)		(__va(gfn_to_pfn(m) << XEN_PAGE_SHIFT))
 
+#define percpu_to_gfn(v)	\
+	(pfn_to_gfn(per_cpu_ptr_to_phys(v) >> XEN_PAGE_SHIFT))
+
 /* Only used in PV code. But ARM guests are always HVM. */
 static inline xmaddr_t arbitrary_virt_to_machine(void *vaddr)
 {