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205 lines
6.1 KiB
205 lines
6.1 KiB
x86: make arch_set_info_guest() preemptible
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.. as the root page table validation (and the dropping of an eventual
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old one) can require meaningful amounts of time.
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This is part of CVE-2013-1918 / XSA-45.
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Acked-by: Tim Deegan <tim@xen.org>
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--- a/xen/arch/x86/domain.c
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+++ b/xen/arch/x86/domain.c
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@@ -858,6 +858,9 @@ int arch_set_info_guest(
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if ( !v->is_initialised )
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{
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+ if ( !compat && !(flags & VGCF_in_kernel) && !c.nat->ctrlreg[1] )
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+ return -EINVAL;
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+
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v->arch.pv_vcpu.ldt_base = c(ldt_base);
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v->arch.pv_vcpu.ldt_ents = c(ldt_ents);
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}
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@@ -955,24 +958,44 @@ int arch_set_info_guest(
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if ( rc != 0 )
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return rc;
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+ set_bit(_VPF_in_reset, &v->pause_flags);
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+
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if ( !compat )
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- {
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cr3_gfn = xen_cr3_to_pfn(c.nat->ctrlreg[3]);
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- cr3_page = get_page_from_gfn(d, cr3_gfn, NULL, P2M_ALLOC);
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-
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- if ( !cr3_page )
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- {
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- destroy_gdt(v);
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- return -EINVAL;
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- }
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- if ( !paging_mode_refcounts(d)
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- && !get_page_type(cr3_page, PGT_base_page_table) )
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- {
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- put_page(cr3_page);
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- destroy_gdt(v);
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- return -EINVAL;
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- }
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+#ifdef CONFIG_COMPAT
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+ else
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+ cr3_gfn = compat_cr3_to_pfn(c.cmp->ctrlreg[3]);
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+#endif
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+ cr3_page = get_page_from_gfn(d, cr3_gfn, NULL, P2M_ALLOC);
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+ if ( !cr3_page )
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+ rc = -EINVAL;
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+ else if ( paging_mode_refcounts(d) )
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+ /* nothing */;
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+ else if ( cr3_page == v->arch.old_guest_table )
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+ {
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+ v->arch.old_guest_table = NULL;
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+ put_page(cr3_page);
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+ }
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+ else
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+ {
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+ /*
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+ * Since v->arch.guest_table{,_user} are both NULL, this effectively
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+ * is just a call to put_old_guest_table().
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+ */
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+ if ( !compat )
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+ rc = vcpu_destroy_pagetables(v);
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+ if ( !rc )
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+ rc = get_page_type_preemptible(cr3_page,
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+ !compat ? PGT_root_page_table
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+ : PGT_l3_page_table);
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+ if ( rc == -EINTR )
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+ rc = -EAGAIN;
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+ }
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+ if ( rc )
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+ /* handled below */;
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+ else if ( !compat )
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+ {
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v->arch.guest_table = pagetable_from_page(cr3_page);
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#ifdef __x86_64__
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if ( c.nat->ctrlreg[1] )
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@@ -980,56 +1003,44 @@ int arch_set_info_guest(
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cr3_gfn = xen_cr3_to_pfn(c.nat->ctrlreg[1]);
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cr3_page = get_page_from_gfn(d, cr3_gfn, NULL, P2M_ALLOC);
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- if ( !cr3_page ||
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- (!paging_mode_refcounts(d)
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- && !get_page_type(cr3_page, PGT_base_page_table)) )
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+ if ( !cr3_page )
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+ rc = -EINVAL;
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+ else if ( !paging_mode_refcounts(d) )
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{
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- if (cr3_page)
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- put_page(cr3_page);
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- cr3_page = pagetable_get_page(v->arch.guest_table);
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- v->arch.guest_table = pagetable_null();
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- if ( paging_mode_refcounts(d) )
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- put_page(cr3_page);
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- else
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- put_page_and_type(cr3_page);
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- destroy_gdt(v);
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- return -EINVAL;
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+ rc = get_page_type_preemptible(cr3_page, PGT_root_page_table);
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+ switch ( rc )
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+ {
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+ case -EINTR:
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+ rc = -EAGAIN;
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+ case -EAGAIN:
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+ v->arch.old_guest_table =
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+ pagetable_get_page(v->arch.guest_table);
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+ v->arch.guest_table = pagetable_null();
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+ break;
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+ }
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}
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-
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- v->arch.guest_table_user = pagetable_from_page(cr3_page);
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- }
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- else if ( !(flags & VGCF_in_kernel) )
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- {
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- destroy_gdt(v);
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- return -EINVAL;
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+ if ( !rc )
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+ v->arch.guest_table_user = pagetable_from_page(cr3_page);
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}
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}
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else
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{
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l4_pgentry_t *l4tab;
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- cr3_gfn = compat_cr3_to_pfn(c.cmp->ctrlreg[3]);
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- cr3_page = get_page_from_gfn(d, cr3_gfn, NULL, P2M_ALLOC);
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-
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- if ( !cr3_page)
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- {
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- destroy_gdt(v);
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- return -EINVAL;
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- }
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-
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- if (!paging_mode_refcounts(d)
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- && !get_page_type(cr3_page, PGT_l3_page_table) )
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- {
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- put_page(cr3_page);
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- destroy_gdt(v);
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- return -EINVAL;
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- }
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-
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l4tab = __va(pagetable_get_paddr(v->arch.guest_table));
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*l4tab = l4e_from_pfn(page_to_mfn(cr3_page),
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_PAGE_PRESENT|_PAGE_RW|_PAGE_USER|_PAGE_ACCESSED);
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#endif
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}
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+ if ( rc )
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+ {
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+ if ( cr3_page )
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+ put_page(cr3_page);
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+ destroy_gdt(v);
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+ return rc;
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+ }
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+
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+ clear_bit(_VPF_in_reset, &v->pause_flags);
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if ( v->vcpu_id == 0 )
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update_domain_wallclock_time(d);
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--- a/xen/common/compat/domain.c
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+++ b/xen/common/compat/domain.c
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@@ -50,6 +50,10 @@ int compat_vcpu_op(int cmd, int vcpuid,
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rc = v->is_initialised ? -EEXIST : arch_set_info_guest(v, cmp_ctxt);
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domain_unlock(d);
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+ if ( rc == -EAGAIN )
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+ rc = hypercall_create_continuation(__HYPERVISOR_vcpu_op, "iih",
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+ cmd, vcpuid, arg);
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+
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xfree(cmp_ctxt);
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break;
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}
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--- a/xen/common/domain.c
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+++ b/xen/common/domain.c
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@@ -849,6 +849,11 @@ long do_vcpu_op(int cmd, int vcpuid, XEN
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domain_unlock(d);
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free_vcpu_guest_context(ctxt);
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+
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+ if ( rc == -EAGAIN )
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+ rc = hypercall_create_continuation(__HYPERVISOR_vcpu_op, "iih",
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+ cmd, vcpuid, arg);
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+
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break;
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case VCPUOP_up: {
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--- a/xen/common/domctl.c
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+++ b/xen/common/domctl.c
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@@ -338,6 +338,10 @@ long do_domctl(XEN_GUEST_HANDLE(xen_domc
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domain_pause(d);
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ret = arch_set_info_guest(v, c);
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domain_unpause(d);
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+
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+ if ( ret == -EAGAIN )
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+ ret = hypercall_create_continuation(
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+ __HYPERVISOR_domctl, "h", u_domctl);
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}
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svc_out:
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