[Xen-devel] [PATCH, resubmit] x86/hvm: determine shared info format earlier

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

Latch guest shared info format when hypercall page is being set up rather
than during an arbitrarily selected hypercall.

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

Index: 2007-06-18/xen/arch/x86/hvm/hvm.c
===================================================================
--- 2007-06-18.orig/xen/arch/x86/hvm/hvm.c      2007-06-18 08:34:29.000000000 
+0200
+++ 2007-06-18/xen/arch/x86/hvm/hvm.c   2007-06-18 10:22:58.000000000 +0200
@@ -836,6 +836,15 @@ void hvm_update_guest_cr3(struct vcpu *v
 void hvm_hypercall_page_initialise(struct domain *d,
                                    void *hypercall_page)
 {
+#ifdef __x86_64__
+    /*
+     * Since this operation is one of the very first executed by PV drivers
+     * on initialisation or after save/restore, it is a sensible point at
+     * which to sample the execution mode of the guest and latch 32- or 64-
+     * bit format for shared state.
+     */
+    d->arch.has_32bit_shinfo = (hvm_guest_x86_mode(current) != 8);
+#endif
     hvm_funcs.init_hypercall_page(d, hypercall_page);
 }
 
@@ -1066,10 +1075,8 @@ long do_hvm_op(unsigned long op, XEN_GUE
             case HVM_PARAM_CALLBACK_IRQ:
                 hvm_set_callback_via(d, a.value);
                 /*
-                 * Since this operation is one of the very first executed
-                 * by PV drivers on initialisation or after save/restore, it
-                 * is a sensible point at which to sample the execution mode of
-                 * the guest and latch 32- or 64-bit format for shared state.
+                 * For compatibility with older PV drivers, also latch guest
+                 * execution mode here.
                  */
                 d->arch.has_32bit_shinfo = (hvm_guest_x86_mode(current) != 8);
                 break;




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