[Xen-devel] [PATCH] x86: restrict HVMOP_pagetable_dying to current

["Jan Beulich" <JBeulich@xxxxxxxx>]

This is not used (and probably was never meant to be) by the tool stack.
Limiting it to the current domain in particular allows to eliminate a
bogus use of vCPU 0 in pagetable_dying().

Remove the now unnecessary domain/vCPU parameters from the wrapper/hook
functions at the same time.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4895,10 +4895,12 @@ long do_hvm_op(unsigned long op, XEN_GUE
             return -ESRCH;
 
         rc = -EINVAL;
-        if ( is_hvm_domain(d) && paging_mode_shadow(d) )
+        if ( unlikely(d != current->domain) )
+            rc = -EOPNOTSUPP;
+        else if ( is_hvm_domain(d) && paging_mode_shadow(d) )
             rc = xsm_hvm_param(XSM_TARGET, d, op);
         if ( !rc )
-            pagetable_dying(d, a.gpa);
+            pagetable_dying(a.gpa);
 
         rcu_unlock_domain(d);
         break;
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -851,15 +851,14 @@ int paging_enable(struct domain *d, u32
 
 /* Called from the guest to indicate that a process is being torn down
  * and therefore its pagetables will soon be discarded */
-void pagetable_dying(struct domain *d, paddr_t gpa)
+void pagetable_dying(paddr_t gpa)
 {
 #ifdef CONFIG_SHADOW_PAGING
-    struct vcpu *v;
+    struct vcpu *curr = current;
 
-    ASSERT(paging_mode_shadow(d));
+    ASSERT(paging_mode_shadow(curr->domain));
 
-    v = d->vcpu[0];
-    v->arch.paging.mode->shadow.pagetable_dying(v, gpa);
+    curr->arch.paging.mode->shadow.pagetable_dying(gpa);
 #else
     BUG();
 #endif
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -4525,8 +4525,9 @@ int sh_remove_l3_shadow(struct domain *d
  * and in the meantime we unhook its top-level user-mode entries. */
 
 #if GUEST_PAGING_LEVELS == 3
-static void sh_pagetable_dying(struct vcpu *v, paddr_t gpa)
+static void sh_pagetable_dying(paddr_t gpa)
 {
+    struct vcpu *v = current;
     struct domain *d = v->domain;
     int i = 0;
     int flush = 0;
@@ -4604,8 +4605,9 @@ out_put_gfn:
     put_gfn(d, l3gfn);
 }
 #else
-static void sh_pagetable_dying(struct vcpu *v, paddr_t gpa)
+static void sh_pagetable_dying(paddr_t gpa)
 {
+    struct vcpu *v = current;
     struct domain *d = v->domain;
     mfn_t smfn, gmfn;
     p2m_type_t p2mt;
--- a/xen/include/asm-x86/paging.h
+++ b/xen/include/asm-x86/paging.h
@@ -95,7 +95,7 @@ struct shadow_paging_mode {
     void          (*destroy_monitor_table )(struct vcpu *v, mfn_t mmfn);
     int           (*guess_wrmap           )(struct vcpu *v, 
                                             unsigned long vaddr, mfn_t gmfn);
-    void          (*pagetable_dying       )(struct vcpu *v, paddr_t gpa);
+    void          (*pagetable_dying       )(paddr_t gpa);
     void          (*trace_emul_write_val  )(const void *ptr, unsigned long 
vaddr,
                                             const void *src, unsigned int 
bytes);
 #endif
@@ -345,7 +345,7 @@ void paging_write_p2m_entry(struct p2m_d
 
 /* Called from the guest to indicate that the a process is being
  * torn down and its pagetables will soon be discarded */
-void pagetable_dying(struct domain *d, paddr_t gpa);
+void pagetable_dying(paddr_t gpa);
 
 /* Print paging-assistance info to the console */
 void paging_dump_domain_info(struct domain *d);





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