[Xen-changelog] [xen master] x86/mem_event: deliver gla fault EPT violation information

[patchbot@xxxxxxx]

commit 692f3cc7dd05b80dbd027e46372b1c25d7975332
Author:     Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>
AuthorDate: Thu Aug 28 16:04:05 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Aug 28 16:04:05 2014 +0200

    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@xxxxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    Acked-by: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/hvm/svm/svm.c        |    8 +++++++-
 xen/arch/x86/hvm/vmx/vmx.c        |    4 ++++
 xen/arch/x86/mm/p2m.c             |    5 ++++-
 xen/include/asm-x86/hvm/svm/svm.h |    6 ++++++
 xen/include/asm-x86/mm.h          |   11 +++++++++++
 xen/include/public/mem_event.h    |    4 +++-
 6 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index d29caa1..b5188e6 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1394,7 +1394,7 @@ const struct hvm_function_table * __init start_svm(void)
 }
 
 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;
@@ -1414,6 +1414,12 @@ static void svm_do_nested_pgfault(struct vcpu *v,
         .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 )
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index d8e1475..26b1ad5 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2391,6 +2391,10 @@ static void ept_handle_violation(unsigned long 
qualification, paddr_t gpa)
     {
         __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;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 1f1f6cd..c2e89e1 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1405,10 +1405,13 @@ bool_t p2m_mem_access_check(paddr_t gpa, unsigned long 
gla,
         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;
     }
 
diff --git a/xen/include/asm-x86/hvm/svm/svm.h 
b/xen/include/asm-x86/hvm/svm/svm.h
index 1ffe6d6..cb2db3f 100644
--- 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__ */
diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
index 1889b25..7b85865 100644
--- 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);
diff --git a/xen/include/public/mem_event.h b/xen/include/public/mem_event.h
index 3831b41..fc12697 100644
--- 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;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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