[Xen-changelog] [xen-unstable] nestedhvm: handle l2 guest MMIO access

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Tim Deegan <tim@xxxxxxx>
# Date 1319452148 -3600
# Node ID ffe861c1d5dfa8f4485052e5600e06124105033f
# Parent  a7ccbc79fc17862c21e34c2f145a5a053711f917
nestedhvm: handle l2 guest MMIO access

Hyper-V starts a root domain which effectively an l2 guest.
Hyper-V passes its devices through to the root domain and
let it do the MMIO accesses. The emulation is done by
Xen (host) and Hyper-V forwards the interrupts to the l2 guest.

Signed-off-by: Christoph Egger <Christoph.Egger@xxxxxxx>
Acked-by: Tim Deegan <tim@xxxxxxx>
Committed-by:  Tim Deegan <tim@xxxxxxx>
---


diff -r a7ccbc79fc17 -r ffe861c1d5df xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c    Fri Oct 21 09:45:24 2011 +0200
+++ b/xen/arch/x86/hvm/hvm.c    Mon Oct 24 11:29:08 2011 +0100
@@ -1208,6 +1208,10 @@
             return 0;
         case NESTEDHVM_PAGEFAULT_INJECT:
             return -1;
+        case NESTEDHVM_PAGEFAULT_MMIO:
+            if ( !handle_mmio() )
+                hvm_inject_exception(TRAP_gp_fault, 0, 0);
+            return 1;
         }
     }
 
diff -r a7ccbc79fc17 -r ffe861c1d5df xen/arch/x86/hvm/svm/nestedsvm.c
--- a/xen/arch/x86/hvm/svm/nestedsvm.c  Fri Oct 21 09:45:24 2011 +0200
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c  Mon Oct 24 11:29:08 2011 +0100
@@ -1161,6 +1161,15 @@
         if ( svm->ns_hostflags.fields.vintrmask )
             if ( !svm->ns_hostflags.fields.rflagsif )
                 return hvm_intblk_rflags_ie;
+
+        /* when l1 guest passes its devices through to the l2 guest
+         * and l2 guest does an MMIO access then we may want to
+         * inject an VMEXIT(#INTR) exitcode into the l1 guest.
+         * Delay the injection because this would result in delivering
+         * an interrupt *within* the execution of an instruction.
+         */
+        if ( v->arch.hvm_vcpu.io_state != HVMIO_none )
+            return hvm_intblk_shadow;
     }
 
     if ( nv->nv_vmexit_pending ) {
diff -r a7ccbc79fc17 -r ffe861c1d5df xen/arch/x86/mm/hap/nested_hap.c
--- a/xen/arch/x86/mm/hap/nested_hap.c  Fri Oct 21 09:45:24 2011 +0200
+++ b/xen/arch/x86/mm/hap/nested_hap.c  Mon Oct 24 11:29:08 2011 +0100
@@ -151,6 +151,9 @@
     mfn = gfn_to_mfn_type_p2m(p2m, L1_gpa >> PAGE_SHIFT, &p2mt, &p2ma, 
                               p2m_query, page_order);
 
+    if ( p2m_is_mmio(p2mt) )
+        return NESTEDHVM_PAGEFAULT_MMIO;
+
     if ( p2m_is_paging(p2mt) || p2m_is_shared(p2mt) || !p2m_is_ram(p2mt) )
         return NESTEDHVM_PAGEFAULT_ERROR;
 
@@ -228,6 +231,8 @@
         return rv;
     case NESTEDHVM_PAGEFAULT_DONE:
         break;
+    case NESTEDHVM_PAGEFAULT_MMIO:
+        return rv;
     default:
         BUG();
         break;
diff -r a7ccbc79fc17 -r ffe861c1d5df xen/include/asm-x86/hvm/nestedhvm.h
--- a/xen/include/asm-x86/hvm/nestedhvm.h       Fri Oct 21 09:45:24 2011 +0200
+++ b/xen/include/asm-x86/hvm/nestedhvm.h       Mon Oct 24 11:29:08 2011 +0100
@@ -50,6 +50,7 @@
 #define NESTEDHVM_PAGEFAULT_DONE   0
 #define NESTEDHVM_PAGEFAULT_INJECT 1
 #define NESTEDHVM_PAGEFAULT_ERROR  2
+#define NESTEDHVM_PAGEFAULT_MMIO   3
 int nestedhvm_hap_nested_page_fault(struct vcpu *v, paddr_t L2_gpa);
 
 /* IO permission map */

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