[Xen-devel] [PATCH v3 09/13] x86/altp2m: alternate p2m memory events.

[Ed White <edmund.h.white@xxxxxxxxx>]

Add a flag to indicate that a memory event occurred in an alternate p2m
and a field containing the p2m index. Allow any event response to switch
to a different alternate p2m using the same flag and field.

Modify p2m_memory_access_check() to handle alternate p2m's.

Signed-off-by: Ed White <edmund.h.white@xxxxxxxxx>
---
 xen/arch/x86/mm/p2m.c         | 20 +++++++++++++++++++-
 xen/common/vm_event.c         |  3 +++
 xen/include/asm-arm/p2m.h     |  6 ++++++
 xen/include/asm-x86/p2m.h     |  3 +++
 xen/include/public/vm_event.h | 11 +++++++++++
 5 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 58d4951..576b28d 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1514,6 +1514,13 @@ void p2m_mem_access_emulate_check(struct vcpu *v,
     }
 }
 
+void p2m_altp2m_check(struct vcpu *v, const vm_event_response_t *rsp)
+{
+    if ( (rsp->flags & VM_EVENT_FLAG_ALTERNATE_P2M) &&
+         altp2m_active(v->domain) )
+        p2m_switch_vcpu_altp2m_by_id(v, rsp->altp2m_idx);
+}
+
 bool_t p2m_mem_access_check(paddr_t gpa, unsigned long gla,
                             struct npfec npfec,
                             vm_event_request_t **req_ptr)
@@ -1521,7 +1528,7 @@ bool_t p2m_mem_access_check(paddr_t gpa, unsigned long 
gla,
     struct vcpu *v = current;
     unsigned long gfn = gpa >> PAGE_SHIFT;
     struct domain *d = v->domain;    
-    struct p2m_domain* p2m = p2m_get_hostp2m(d);
+    struct p2m_domain *p2m = NULL;
     mfn_t mfn;
     p2m_type_t p2mt;
     p2m_access_t p2ma;
@@ -1529,6 +1536,11 @@ bool_t p2m_mem_access_check(paddr_t gpa, unsigned long 
gla,
     int rc;
     unsigned long eip = guest_cpu_user_regs()->eip;
 
+    if ( altp2m_active(d) )
+        p2m = p2m_get_altp2m(v);
+    if ( !p2m )
+        p2m = p2m_get_hostp2m(d);
+
     /* First, handle rx2rw conversion automatically.
      * These calls to p2m->set_entry() must succeed: we have the gfn
      * locked and just did a successful get_entry(). */
@@ -1635,6 +1647,12 @@ bool_t p2m_mem_access_check(paddr_t gpa, unsigned long 
gla,
         req->vcpu_id = v->vcpu_id;
 
         p2m_vm_event_fill_regs(req);
+
+        if ( altp2m_active(v->domain) )
+        {
+            req->flags |= VM_EVENT_FLAG_ALTERNATE_P2M;
+            req->altp2m_idx = vcpu_altp2m(v).p2midx;
+        }
     }
 
     /* Pause the current VCPU */
diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index 120a78a..57095d8 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -399,6 +399,9 @@ void vm_event_resume(struct domain *d, struct 
vm_event_domain *ved)
 
         };
 
+        /* Check for altp2m switch */
+        p2m_altp2m_check(v, &rsp);
+
         /* Unpause domain. */
         if ( rsp.flags & VM_EVENT_FLAG_VCPU_PAUSED )
             vm_event_vcpu_unpause(v);
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index 63748ef..3206c75 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -109,6 +109,12 @@ void p2m_mem_access_emulate_check(struct vcpu *v,
     /* Not supported on ARM. */
 }
 
+static inline
+void p2m_altp2m_check(struct vcpu *v, const vm_event_response_t *rsp)
+{
+    /* Not supported on ARM. */
+}
+
 #define p2m_is_foreign(_t)  ((_t) == p2m_map_foreign)
 #define p2m_is_ram(_t)      ((_t) == p2m_ram_rw || (_t) == p2m_ram_ro)
 
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index bf5e5cb..5689f40 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -762,6 +762,9 @@ uint16_t p2m_find_altp2m_by_eptp(struct domain *d, uint64_t 
eptp);
 /* Switch alternate p2m for a single vcpu */
 bool_t p2m_switch_vcpu_altp2m_by_id(struct vcpu *v, uint16_t idx);
 
+/* Check to see if vcpu should be switched to a different p2m. */
+void p2m_altp2m_check(struct vcpu *v, const vm_event_response_t *rsp);
+
 /*
  * p2m type to IOMMU flags
  */
diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
index 577e971..6dfa9db 100644
--- a/xen/include/public/vm_event.h
+++ b/xen/include/public/vm_event.h
@@ -47,6 +47,16 @@
 #define VM_EVENT_FLAG_VCPU_PAUSED     (1 << 0)
 /* Flags to aid debugging mem_event */
 #define VM_EVENT_FLAG_FOREIGN         (1 << 1)
+/*
+ * This flag can be set in a request or a response
+ *
+ * On a request, indicates that the event occurred in the alternate p2m 
specified by
+ * the altp2m_idx request field.
+ *
+ * On a response, indicates that the VCPU should resume in the alternate p2m 
specified
+ * by the altp2m_idx response field if possible.
+ */
+#define VM_EVENT_FLAG_ALTERNATE_P2M   (1 << 2)
 
 /*
  * Reasons for the vm event request
@@ -194,6 +204,7 @@ typedef struct vm_event_st {
     uint32_t flags;     /* VM_EVENT_FLAG_* */
     uint32_t reason;    /* VM_EVENT_REASON_* */
     uint32_t vcpu_id;
+    uint16_t altp2m_idx; /* may be used during request and response */
 
     union {
         struct vm_event_paging                mem_paging;
-- 
1.9.1


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