[PATCH v3 11/15] xen/arm: Instruction prefetch abort (X) mem_event handling

[Tamas K Lengyel <tklengyel@sec.in.tum.de>]

Add missing structure definition for iabt and update the trap handling
mechanism to only inject the exception if the mem_access checker
decides to do so.

Signed-off-by: Tamas K Lengyel <tklengyel@sec.in.tum.de>
---
v2: Add definition for instruction abort instruction fetch status codes (enum iabt_ifsc)
       and only call p2m_mem_access_check for traps triggered for permission violations.
---
 xen/arch/arm/traps.c            | 43 ++++++++++++++++++++++++++++++++++++++++-
 xen/include/asm-arm/processor.h | 40 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 7eb875a..985f5b4 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1828,7 +1828,48 @@ done:
 static void do_trap_instr_abort_guest(struct cpu_user_regs *regs,
                                       union hsr hsr)
 {
-    register_t addr = READ_SYSREG(FAR_EL2);
+    struct hsr_iabt iabt = hsr.iabt;
+    int rc;
+    register_t addr;
+    vaddr_t gva;
+    paddr_t gpa;
+
+#ifdef CONFIG_ARM_32
+    gva = READ_CP32(HIFAR);
+#else
+    gva = READ_SYSREG64(FAR_EL2);
+#endif
+
+    rc = gva_to_ipa(gva, &gpa);
+    if ( rc == -EFAULT )
+        return;
+
+    switch ( iabt.ifsc )
+    {
+    case IABT_IFSC_PERMISSION_1:
+    case IABT_IFSC_PERMISSION_2:
+    case IABT_IFSC_PERMISSION_3:
+    {
+        struct npfec npfec = {
+            .read_access = 1,
+            .insn_fetch = 1,
+            .gla_valid = 1,
+            .kind = iabt.s1ptw ? npfec_kind_in_gpt : npfec_kind_with_gla
+        };
+
+        rc = p2m_mem_access_check(gpa, gva, npfec);
+
+        /* Trap was triggered by mem_access, work here is done */
+        if ( !rc )
+            return;
+    }
+    break;
+
+    default:
+        break;
+    }
+
+    addr = READ_SYSREG(FAR_EL2);
     inject_iabt_exception(regs, addr, hsr.len);
 }
 
diff --git a/xen/include/asm-arm/processor.h b/xen/include/asm-arm/processor.h
index b844f1d..044de12 100644
--- a/xen/include/asm-arm/processor.h
+++ b/xen/include/asm-arm/processor.h
@@ -292,6 +292,36 @@ enum dabt_dfsc {
     DABT_DFSC_TLB_CONFLICT      = 0b110000,
 };
 
+/* Instruction abort instruction fault status codes */
+enum iabt_ifsc {
+    IABT_IFSC_ADDR_SIZE_0       = 0b000000,
+    IABT_IFSC_ADDR_SIZE_1       = 0b000001,
+    IABT_IFSC_ADDR_SIZE_2       = 0b000010,
+    IABT_IFSC_ADDR_SIZE_3       = 0b000011,
+    IABT_IFSC_TRANSLATION_0     = 0b000100,
+    IABT_IFSC_TRANSLATION_1     = 0b000101,
+    IABT_IFSC_TRANSLATION_2     = 0b000110,
+    IABT_IFSC_TRANSLATION_3     = 0b000111,
+    IABT_IFSC_ACCESS_1          = 0b001001,
+    IABT_IFSC_ACCESS_2          = 0b001010,
+    IABT_IFSC_ACCESS_3          = 0b001011,
+    IABT_IFSC_PERMISSION_1      = 0b001101,
+    IABT_IFSC_PERMISSION_2      = 0b001110,
+    IABT_IFSC_PERMISSION_3      = 0b001111,
+    IABT_IFSC_SYNC_EXT          = 0b010000,
+    IABT_IFSC_SYNC_PARITY       = 0b011000,
+    IABT_IFSC_SYNC_EXT_TTW_0    = 0b010100,
+    IABT_IFSC_SYNC_EXT_TTW_1    = 0b010101,
+    IABT_IFSC_SYNC_EXT_TTW_2    = 0b010110,
+    IABT_IFSC_SYNC_EXT_TTW_3    = 0b010111,
+    IABT_IFSC_SYNC_PARITY_TTW_0 = 0b011100,
+    IABT_IFSC_SYNC_PARITY_TTW_1 = 0b011101,
+    IABT_IFSC_SYNC_PARITY_TTW_2 = 0b011110,
+    IABT_IFSC_SYNC_PARITY_TTW_3 = 0b011111,
+    IABT_IFSC_ALIGNMENT         = 0b100001,
+    IABT_IFSC_TLB_CONFLICT      = 0b110000,
+};
+
 union hsr {
     uint32_t bits;
     struct {
@@ -371,10 +401,18 @@ union hsr {
     } sysreg; /* HSR_EC_SYSREG */
 #endif
 
+    struct hsr_iabt {
+        unsigned long ifsc:6;   /* Instruction fault status code */
+        unsigned long res0:1;
+        unsigned long s1ptw:1;  /* Fault during a stage 1 translation table walk */
+        unsigned long res1:1;
+        unsigned long ea:1;     /* External abort type */
+    } iabt; /* HSR_EC_INSTR_ABORT_* */
+
     struct hsr_dabt {
         unsigned long dfsc:6;  /* Data Fault Status Code */
         unsigned long write:1; /* Write / not Read */
-        unsigned long s1ptw:1; /* */
+        unsigned long s1ptw:1; /* Fault during a stage 1 translation table walk */
         unsigned long cache:1; /* Cache Maintenance */
         unsigned long eat:1;   /* External Abort Type */
 #ifdef CONFIG_ARM_32
-- 
2.1.0.rc1