x86/hvm/ioreq: Fix condition in hvm_alloc_legacy_ioreq_gfn()

Fix the incorrect condition that causes hvm_alloc_legacy_ioreq_gfn()
to return INVALID_GFN even if the HVM param was installed properly by
the toolstack.

Fixes: 3486f398a3 (' x86/hvm/ioreq: allow ioreq servers to use HVM_PARAM_[BUF]IOREQ_PFN')
Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 282ed258a5
master date: 2025-08-18 10:43:52 +0200

xen/arch/x86/hvm/ioreq.c

@@ -63,7 +63,7 @@ static gfn_t hvm_alloc_legacy_ioreq_gfn(struct ioreq_server *s)
 
     for ( i = HVM_PARAM_IOREQ_PFN; i <= HVM_PARAM_BUFIOREQ_PFN; i++ )
     {
-        if ( !test_and_clear_bit(i, &d->arch.hvm.ioreq_gfn.legacy_mask) )
+        if ( test_and_clear_bit(i, &d->arch.hvm.ioreq_gfn.legacy_mask) )
             return _gfn(d->arch.hvm.params[i]);
     }