xen/53ff36d5-x86-mem_event-deliver-gla-fault-EPT-violation-information.patch

References: bnc#882089

# Commit 692f3cc7dd05b80dbd027e46372b1c25d7975332
# Date 2014-08-28 16:04:05 +0200
# Author Tamas K Lengyel <tamas.lengyel@zentific.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86/mem_event: deliver gla fault EPT violation information

On Intel EPT the exit qualification generated by a violation also
includes a bit (EPT_GLA_FAULT) which describes the following
information: Set if the access causing the EPT violation is to a
guest-physical address that is the translation of a linear address.
Clear if the access causing the EPT violation is to a paging-structure
entry as part of a page walk or the update of an accessed or dirty bit.

For more information see Table 27-7 in the Intel SDM.

This patch extends the mem_event system to deliver this extra
information, which could be useful for determining the cause of a
violation.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@zentific.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Tim Deegan <tim@xen.org>

--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1289,7 +1289,7 @@ const struct hvm_function_table * __init
 }
 
 static void svm_do_nested_pgfault(struct vcpu *v,
-    struct cpu_user_regs *regs, uint32_t pfec, paddr_t gpa)
+    struct cpu_user_regs *regs, uint64_t pfec, paddr_t gpa)
 {
     int ret;
     unsigned long gfn = gpa >> PAGE_SHIFT;
@@ -1309,6 +1309,12 @@ static void svm_do_nested_pgfault(struct
         .insn_fetch = !!(pfec & PFEC_insn_fetch)
     };
 
+    /* These bits are mutually exclusive */
+    if ( pfec & NPT_PFEC_with_gla )
+        npfec.kind = npfec_kind_with_gla;
+    else if ( pfec & NPT_PFEC_in_gpt )
+        npfec.kind = npfec_kind_in_gpt;
+
     ret = hvm_hap_nested_page_fault(gpa, ~0ul, npfec);
 
     if ( tb_init_done )
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2317,6 +2317,10 @@ static void ept_handle_violation(unsigne
     {
         __vmread(GUEST_LINEAR_ADDRESS, &gla);
         npfec.gla_valid = 1;
+        if( qualification & EPT_GLA_FAULT )
+            npfec.kind = npfec_kind_with_gla;
+        else
+            npfec.kind = npfec_kind_in_gpt;
     }
     else
         gla = ~0ull;
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1343,10 +1343,13 @@ bool_t p2m_mem_access_check(paddr_t gpa,
         req->offset = gpa & ((1 << PAGE_SHIFT) - 1);
         req->gla_valid = npfec.gla_valid;
         req->gla = gla;
+        if ( npfec.kind == npfec_kind_with_gla )
+            req->fault_with_gla = 1;
+        else if ( npfec.kind == npfec_kind_in_gpt )
+            req->fault_in_gpt = 1;
         req->access_r = npfec.read_access;
         req->access_w = npfec.write_access;
         req->access_x = npfec.insn_fetch;
-    
         req->vcpu_id = v->vcpu_id;
     }
 
--- a/xen/include/asm-x86/hvm/svm/svm.h
+++ b/xen/include/asm-x86/hvm/svm/svm.h
@@ -105,4 +105,10 @@ extern u32 svm_feature_flags;
 extern void svm_host_osvw_reset(void);
 extern void svm_host_osvw_init(void);
 
+/* EXITINFO1 fields on NPT faults */
+#define _NPT_PFEC_with_gla     32
+#define NPT_PFEC_with_gla      (1UL<<_NPT_PFEC_with_gla)
+#define _NPT_PFEC_in_gpt       33
+#define NPT_PFEC_in_gpt        (1UL<<_NPT_PFEC_in_gpt)
+
 #endif /* __ASM_X86_HVM_SVM_H__ */
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -552,6 +552,16 @@ void audit_domains(void);
 #endif
 
 /*
+ * Extra fault info types which are used to further describe
+ * the source of an access violation.
+ */
+typedef enum {
+    npfec_kind_unknown, /* must be first */
+    npfec_kind_in_gpt,  /* violation in guest page table */
+    npfec_kind_with_gla /* violation with guest linear address */
+} npfec_kind_t;
+
+/*
  * Nested page fault exception codes.
  */
 struct npfec {
@@ -559,6 +569,7 @@ struct npfec {
     unsigned int write_access:1;
     unsigned int insn_fetch:1;
     unsigned int gla_valid:1;
+    unsigned int kind:2;  /* npfec_kind_t */
 };
 
 int new_guest_cr3(unsigned long pfn);
--- a/xen/include/public/mem_event.h
+++ b/xen/include/public/mem_event.h
@@ -62,7 +62,9 @@ typedef struct mem_event_st {
     uint16_t access_w:1;
     uint16_t access_x:1;
     uint16_t gla_valid:1;
-    uint16_t available:12;
+    uint16_t fault_with_gla:1;
+    uint16_t fault_in_gpt:1;
+    uint16_t available:10;
 
     uint16_t reason;
 } mem_event_request_t, mem_event_response_t;