[Xen-devel] [PATCH v6 09/15] 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_mem_access_check() to handle alternate p2m's.

Signed-off-by: Ed White <edmund.h.white@xxxxxxxxx>

Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> for the x86 bits.
Acked-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Acked-by: Tamas K Lengyel <tlengyel@xxxxxxxxxxx>
---
 xen/arch/x86/mm/p2m.c         | 19 ++++++++++++++++++-
 xen/common/vm_event.c         |  4 ++++
 xen/include/asm-arm/p2m.h     |  6 ++++++
 xen/include/asm-x86/p2m.h     |  3 +++
 xen/include/public/vm_event.h | 12 ++++++++++++
 5 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 93ecd87..ed3e65f 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1522,6 +1522,12 @@ void p2m_mem_access_emulate_check(struct vcpu *v,
     }
 }
 
+void p2m_altp2m_check(struct vcpu *v, uint16_t idx)
+{
+    if ( altp2m_active(v->domain) )
+        p2m_switch_vcpu_altp2m_by_id(v, idx);
+}
+
 bool_t p2m_mem_access_check(paddr_t gpa, unsigned long gla,
                             struct npfec npfec,
                             vm_event_request_t **req_ptr)
@@ -1529,7 +1535,7 @@ 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;
@@ -1537,6 +1543,11 @@ 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(). */
@@ -1651,6 +1662,12 @@ 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 4c6bf98..f3a8736 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -412,6 +412,10 @@ void vm_event_resume(struct domain *d, struct 
vm_event_domain *ved)
 
         };
 
+        /* Check for altp2m switch */
+        if ( rsp.flags & VM_EVENT_FLAG_ALTERNATE_P2M )
+            p2m_altp2m_check(v, rsp.altp2m_idx);
+
         if ( rsp.flags & VM_EVENT_FLAG_VCPU_PAUSED )
         {
             if ( rsp.flags & VM_EVENT_FLAG_TOGGLE_SINGLESTEP )
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index 63748ef..08bdce3 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, uint16_t idx)
+{
+    /* 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 0a172e0..722e54c 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -751,6 +751,9 @@ 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, uint16_t idx);
+
 /*
  * p2m type to IOMMU flags
  */
diff --git a/xen/include/public/vm_event.h b/xen/include/public/vm_event.h
index fbc76b2..ff2f217 100644
--- a/xen/include/public/vm_event.h
+++ b/xen/include/public/vm_event.h
@@ -79,6 +79,16 @@
   * Currently only useful for MSR, CR0, CR3 and CR4 write events.
   */
 #define VM_EVENT_FLAG_DENY               (1 << 6)
+/*
+ * 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 << 7)
 
 /*
  * Reasons for the vm event request
@@ -221,6 +231,8 @@ 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 */
+    uint16_t _pad[3];
 
     union {
         struct vm_event_paging                mem_paging;
-- 
1.9.1


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