[Qemu-devel] [PATCH v2 0/9] target-i386: Implement debug extensions

[Qemu-devel] [PATCH v2 0/9] target-i386: Implement debug extensions

[Eduardo Habkost]

Updated version of the series submitted by Richard Henderson.

With the additional changes, the kvm-unit-tests debug extensions test case
written by Paolo passes all tests except ICEBP.

Changes v1 -> v2:
* Patch 2/9: Included fix from Paolo to make sure dr7 is updated
  after hw_breakpoint_remove() call and before hw_breakpoint_insert()
  call
* New patch (3/9): Ensure bit 10 on DR7 is never cleared
* Patch 6/9: Rebase on top of new version of patch 2/9
* New patch (8/9): Ensure always-1 bits on DR6 can't be cleared
* New patch (9/9): Add DE to TCG_FEATURES

Eduardo Habkost (3):
  target-i386: Ensure bit 10 on DR7 is never cleared
  target-i386: Ensure always-1 bits on DR6 can't be cleared
  target-i386: Add DE to TCG_FEATURES

Richard Henderson (6):
  target-i386: Introduce cpu_x86_update_dr7
  target-i386: Re-introduce optimal breakpoint removal
  target-i386: Move hw_*breakpoint_* functions
  target-i386: Optimize setting dr[0-3]
  target-i386: Handle I/O breakpoints
  target-i386: Check CR4[DE] for processing DR4/DR5

 target-i386/bpt_helper.c | 223 ++++++++++++++++++++++++++++++++++++++---------
 target-i386/cpu.c        |   2 +-
 target-i386/cpu.h        |  35 ++------
 target-i386/helper.h     |   4 +-
 target-i386/machine.c    |   8 +-
 target-i386/seg_helper.c |   8 +-
 target-i386/translate.c  |  30 +++++--
 7 files changed, 224 insertions(+), 86 deletions(-)

-- 
2.1.0

[Qemu-devel] [PATCH v2 1/9] target-i386: Introduce cpu_x86_update_dr7

[Eduardo Habkost]

From: Richard Henderson <rth@twiddle.net>

This moves the last of the iteration over breakpoints into
the bpt_helper.c file.  This also allows us to make several
breakpoint functions static.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/bpt_helper.c | 29 ++++++++++++++++++-----------
 target-i386/cpu.h        |  4 ++--
 target-i386/machine.c    |  8 ++++++--
 target-i386/seg_helper.c |  8 +-------
 4 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index c071c24..f14788a 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -21,7 +21,8 @@
 #include "exec/helper-proto.h"
 
 
-void hw_breakpoint_insert(CPUX86State *env, int index)
+#ifndef CONFIG_USER_ONLY
+static void hw_breakpoint_insert(CPUX86State *env, int index)
 {
     CPUState *cs = CPU(x86_env_get_cpu(env));
     int type = 0, err = 0;
@@ -55,7 +56,7 @@ void hw_breakpoint_insert(CPUX86State *env, int index)
     }
 }
 
-void hw_breakpoint_remove(CPUX86State *env, int index)
+static void hw_breakpoint_remove(CPUX86State *env, int index)
 {
     CPUState *cs;
 
@@ -79,6 +80,20 @@ void hw_breakpoint_remove(CPUX86State *env, int index)
     }
 }
 
+void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
+{
+    int i;
+
+    for (i = 0; i < DR7_MAX_BP; i++) {
+        hw_breakpoint_remove(env, i);
+    }
+    env->dr[7] = new_dr7;
+    for (i = 0; i < DR7_MAX_BP; i++) {
+        hw_breakpoint_insert(env, i);
+    }
+}
+#endif
+
 static bool check_hw_breakpoints(CPUX86State *env, bool force_dr6_update)
 {
     target_ulong dr6;
@@ -161,20 +176,12 @@ void helper_single_step(CPUX86State *env)
 void helper_movl_drN_T0(CPUX86State *env, int reg, target_ulong t0)
 {
 #ifndef CONFIG_USER_ONLY
-    int i;
-
     if (reg < 4) {
         hw_breakpoint_remove(env, reg);
         env->dr[reg] = t0;
         hw_breakpoint_insert(env, reg);
     } else if (reg == 7) {
-        for (i = 0; i < DR7_MAX_BP; i++) {
-            hw_breakpoint_remove(env, i);
-        }
-        env->dr[7] = t0;
-        for (i = 0; i < DR7_MAX_BP; i++) {
-            hw_breakpoint_insert(env, i);
-        }
+        cpu_x86_update_dr7(env, t0);
     } else {
         env->dr[reg] = t0;
     }
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 54d9d50..c818801 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -235,6 +235,7 @@
 #define DR7_TYPE_SHIFT  16
 #define DR7_LEN_SHIFT   18
 #define DR7_FIXED_1     0x00000400
+#define DR7_GLOBAL_BP_MASK   0xaa
 #define DR7_LOCAL_BP_MASK    0x55
 #define DR7_MAX_BP           4
 #define DR7_TYPE_BP_INST     0x0
@@ -1153,14 +1154,13 @@ static inline int hw_breakpoint_len(unsigned long dr7, int index)
     return (len == 2) ? 8 : len + 1;
 }
 
-void hw_breakpoint_insert(CPUX86State *env, int index);
-void hw_breakpoint_remove(CPUX86State *env, int index);
 void breakpoint_handler(CPUState *cs);
 
 /* will be suppressed */
 void cpu_x86_update_cr0(CPUX86State *env, uint32_t new_cr0);
 void cpu_x86_update_cr3(CPUX86State *env, target_ulong new_cr3);
 void cpu_x86_update_cr4(CPUX86State *env, uint32_t new_cr4);
+void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7);
 
 /* hw/pc.c */
 uint64_t cpu_get_tsc(CPUX86State *env);
diff --git a/target-i386/machine.c b/target-i386/machine.c
index 9fa0563..f2d8d56 100644
--- a/target-i386/machine.c
+++ b/target-i386/machine.c
@@ -367,8 +367,12 @@ static int cpu_post_load(void *opaque, int version_id)
 
     cpu_breakpoint_remove_all(cs, BP_CPU);
     cpu_watchpoint_remove_all(cs, BP_CPU);
-    for (i = 0; i < DR7_MAX_BP; i++) {
-        hw_breakpoint_insert(env, i);
+    {
+        /* Indicate all breakpoints disabled, as they are, then
+           let the helper re-enable them.  */
+        target_ulong dr7 = env->dr[7];
+        env->dr[7] = dr7 & ~(DR7_GLOBAL_BP_MASK | DR7_LOCAL_BP_MASK);
+        cpu_x86_update_dr7(env, dr7);
     }
     tlb_flush(cs, 1);
 
diff --git a/target-i386/seg_helper.c b/target-i386/seg_helper.c
index 1cbe559..20ee892 100644
--- a/target-i386/seg_helper.c
+++ b/target-i386/seg_helper.c
@@ -501,13 +501,7 @@ static void switch_tss_ra(CPUX86State *env, int tss_selector,
 #ifndef CONFIG_USER_ONLY
     /* reset local breakpoints */
     if (env->dr[7] & DR7_LOCAL_BP_MASK) {
-        for (i = 0; i < DR7_MAX_BP; i++) {
-            if (hw_local_breakpoint_enabled(env->dr[7], i) &&
-                !hw_global_breakpoint_enabled(env->dr[7], i)) {
-                hw_breakpoint_remove(env, i);
-            }
-        }
-        env->dr[7] &= ~DR7_LOCAL_BP_MASK;
+        cpu_x86_update_dr7(env, env->dr[7] & ~DR7_LOCAL_BP_MASK);
     }
 #endif
 }
-- 
2.1.0

[Qemu-devel] [PATCH v2 2/9] target-i386: Re-introduce optimal breakpoint removal

[Eduardo Habkost]

From: Richard Henderson <rth@twiddle.net>

Before the last patch, we had an efficient loop that disabled
local breakpoints on task switch.  Re-add that, but in a more
general way that handles changes to the global enable bits too.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Changes v1 -> v2:
* Included fix from Paolo to make sure dr7 is updated after
  hw_breakpoint_remove() call and before hw_breakpoint_insert()
  call
---
 target-i386/bpt_helper.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index f14788a..23ce828 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -82,14 +82,36 @@ static void hw_breakpoint_remove(CPUX86State *env, int index)
 
 void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
 {
+    target_ulong old_dr7 = env->dr[7];
     int i;
 
-    for (i = 0; i < DR7_MAX_BP; i++) {
-        hw_breakpoint_remove(env, i);
-    }
-    env->dr[7] = new_dr7;
-    for (i = 0; i < DR7_MAX_BP; i++) {
-        hw_breakpoint_insert(env, i);
+    /* If nothing is changing except the global/local enable bits,
+       then we can make the change more efficient.  */
+    if (((old_dr7 ^ new_dr7) & ~0xff) == 0) {
+        /* Fold the global and local enable bits together into the
+           global fields, then xor to show which registers have
+           changed collective enable state.  */
+        int mod = ((old_dr7 | old_dr7 * 2) ^ (new_dr7 | new_dr7 * 2)) & 0xff;
+
+        for (i = 0; i < DR7_MAX_BP; i++) {
+            if ((mod & (2 << i * 2)) && !hw_breakpoint_enabled(new_dr7, i)) {
+                hw_breakpoint_remove(env, i);
+            }
+        }
+        env->dr[7] = new_dr7;
+        for (i = 0; i < DR7_MAX_BP; i++) {
+            if (mod & (2 << i * 2) && hw_breakpoint_enabled(new_dr7, i)) {
+                hw_breakpoint_insert(env, i);
+            }
+        }
+    } else {
+        for (i = 0; i < DR7_MAX_BP; i++) {
+            hw_breakpoint_remove(env, i);
+        }
+        env->dr[7] = new_dr7;
+        for (i = 0; i < DR7_MAX_BP; i++) {
+            hw_breakpoint_insert(env, i);
+        }
     }
 }
 #endif
-- 
2.1.0

[Qemu-devel] [PATCH v2 3/9] target-i386: Ensure bit 10 on DR7 is never cleared

[Eduardo Habkost]

Bit 10 of DR7 is documented as always set to 1, so ensure that's
always the case.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/bpt_helper.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index 23ce828..493deba 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -113,6 +113,8 @@ void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
             hw_breakpoint_insert(env, i);
         }
     }
+
+    env->dr[7] |= DR7_FIXED_1;
 }
 #endif
 
-- 
2.1.0

[Qemu-devel] [PATCH v2 4/9] target-i386: Move hw_*breakpoint_* functions

[Eduardo Habkost]

From: Richard Henderson <rth@twiddle.net>

They're only used from bpt_helper.c now.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/bpt_helper.c | 29 ++++++++++++++++++++++++++++-
 target-i386/cpu.h        | 27 ---------------------------
 2 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index 493deba..afa28df 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -22,6 +22,33 @@
 
 
 #ifndef CONFIG_USER_ONLY
+static inline bool hw_local_breakpoint_enabled(unsigned long dr7, int index)
+{
+    return (dr7 >> (index * 2)) & 1;
+}
+
+static inline bool hw_global_breakpoint_enabled(unsigned long dr7, int index)
+{
+    return (dr7 >> (index * 2)) & 2;
+
+}
+static inline bool hw_breakpoint_enabled(unsigned long dr7, int index)
+{
+    return hw_global_breakpoint_enabled(dr7, index) ||
+           hw_local_breakpoint_enabled(dr7, index);
+}
+
+static inline int hw_breakpoint_type(unsigned long dr7, int index)
+{
+    return (dr7 >> (DR7_TYPE_SHIFT + (index * 4))) & 3;
+}
+
+static inline int hw_breakpoint_len(unsigned long dr7, int index)
+{
+    int len = ((dr7 >> (DR7_LEN_SHIFT + (index * 4))) & 3);
+    return (len == 2) ? 8 : len + 1;
+}
+
 static void hw_breakpoint_insert(CPUX86State *env, int index)
 {
     CPUState *cs = CPU(x86_env_get_cpu(env));
@@ -116,7 +143,6 @@ void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
 
     env->dr[7] |= DR7_FIXED_1;
 }
-#endif
 
 static bool check_hw_breakpoints(CPUX86State *env, bool force_dr6_update)
 {
@@ -187,6 +213,7 @@ void breakpoint_handler(CPUState *cs)
         }
     }
 }
+#endif
 
 void helper_single_step(CPUX86State *env)
 {
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index c818801..c9e4edf 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -1127,33 +1127,6 @@ void x86_stl_phys(CPUState *cs, hwaddr addr, uint32_t val);
 void x86_stq_phys(CPUState *cs, hwaddr addr, uint64_t val);
 #endif
 
-static inline bool hw_local_breakpoint_enabled(unsigned long dr7, int index)
-{
-    return (dr7 >> (index * 2)) & 1;
-}
-
-static inline bool hw_global_breakpoint_enabled(unsigned long dr7, int index)
-{
-    return (dr7 >> (index * 2)) & 2;
-
-}
-static inline bool hw_breakpoint_enabled(unsigned long dr7, int index)
-{
-    return hw_global_breakpoint_enabled(dr7, index) ||
-           hw_local_breakpoint_enabled(dr7, index);
-}
-
-static inline int hw_breakpoint_type(unsigned long dr7, int index)
-{
-    return (dr7 >> (DR7_TYPE_SHIFT + (index * 4))) & 3;
-}
-
-static inline int hw_breakpoint_len(unsigned long dr7, int index)
-{
-    int len = ((dr7 >> (DR7_LEN_SHIFT + (index * 4))) & 3);
-    return (len == 2) ? 8 : len + 1;
-}
-
 void breakpoint_handler(CPUState *cs);
 
 /* will be suppressed */
-- 
2.1.0

[Qemu-devel] [PATCH v2 5/9] target-i386: Optimize setting dr[0-3]

[Eduardo Habkost]

From: Richard Henderson <rth@twiddle.net>

If the debug register is not enabled, we need
do nothing besides update the register.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/bpt_helper.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index afa28df..0563abd 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -228,9 +228,14 @@ void helper_movl_drN_T0(CPUX86State *env, int reg, target_ulong t0)
 {
 #ifndef CONFIG_USER_ONLY
     if (reg < 4) {
-        hw_breakpoint_remove(env, reg);
-        env->dr[reg] = t0;
-        hw_breakpoint_insert(env, reg);
+        if (hw_breakpoint_enabled(env->dr[7], reg)
+            && hw_breakpoint_type(env->dr[7], reg) != DR7_TYPE_IO_RW) {
+            hw_breakpoint_remove(env, reg);
+            env->dr[reg] = t0;
+            hw_breakpoint_insert(env, reg);
+        } else {
+            env->dr[reg] = t0;
+        }
     } else if (reg == 7) {
         cpu_x86_update_dr7(env, t0);
     } else {
-- 
2.1.0

[Qemu-devel] [PATCH v2 6/9] target-i386: Handle I/O breakpoints

[Eduardo Habkost]

From: Richard Henderson <rth@twiddle.net>

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Changes v1 -> v2:
* Rebase on top of new version of "Re-introduce optimal breakpoint
  removal"
---
 target-i386/bpt_helper.c | 98 +++++++++++++++++++++++++++++++++++-------------
 target-i386/cpu.h        |  2 +
 target-i386/helper.h     |  1 +
 target-i386/translate.c  | 20 +++++++++-
 4 files changed, 93 insertions(+), 28 deletions(-)

diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index 0563abd..00f3942 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -49,60 +49,72 @@ static inline int hw_breakpoint_len(unsigned long dr7, int index)
     return (len == 2) ? 8 : len + 1;
 }
 
-static void hw_breakpoint_insert(CPUX86State *env, int index)
+static int hw_breakpoint_insert(CPUX86State *env, int index)
 {
     CPUState *cs = CPU(x86_env_get_cpu(env));
-    int type = 0, err = 0;
+    target_ulong dr7 = env->dr[7];
+    target_ulong drN = env->dr[index];
+    int err = 0;
 
-    switch (hw_breakpoint_type(env->dr[7], index)) {
+    switch (hw_breakpoint_type(dr7, index)) {
     case DR7_TYPE_BP_INST:
-        if (hw_breakpoint_enabled(env->dr[7], index)) {
-            err = cpu_breakpoint_insert(cs, env->dr[index], BP_CPU,
+        if (hw_breakpoint_enabled(dr7, index)) {
+            err = cpu_breakpoint_insert(cs, drN, BP_CPU,
                                         &env->cpu_breakpoint[index]);
         }
         break;
-    case DR7_TYPE_DATA_WR:
-        type = BP_CPU | BP_MEM_WRITE;
-        break;
+
     case DR7_TYPE_IO_RW:
-        /* No support for I/O watchpoints yet */
+        /* Notice when we should enable calls to bpt_io.  */
+        return (hw_breakpoint_enabled(env->dr[7], index)
+                ? HF_IOBPT_MASK : 0);
+
+    case DR7_TYPE_DATA_WR:
+        if (hw_breakpoint_enabled(dr7, index)) {
+            err = cpu_watchpoint_insert(cs, drN,
+                                        hw_breakpoint_len(dr7, index),
+                                        BP_CPU | BP_MEM_WRITE,
+                                        &env->cpu_watchpoint[index]);
+        }
         break;
+
     case DR7_TYPE_DATA_RW:
-        type = BP_CPU | BP_MEM_ACCESS;
+        if (hw_breakpoint_enabled(dr7, index)) {
+            err = cpu_watchpoint_insert(cs, drN,
+                                        hw_breakpoint_len(dr7, index),
+                                        BP_CPU | BP_MEM_ACCESS,
+                                        &env->cpu_watchpoint[index]);
+        }
         break;
     }
-
-    if (type != 0) {
-        err = cpu_watchpoint_insert(cs, env->dr[index],
-                                    hw_breakpoint_len(env->dr[7], index),
-                                    type, &env->cpu_watchpoint[index]);
-    }
-
     if (err) {
         env->cpu_breakpoint[index] = NULL;
     }
+    return 0;
 }
 
 static void hw_breakpoint_remove(CPUX86State *env, int index)
 {
-    CPUState *cs;
+    CPUState *cs = CPU(x86_env_get_cpu(env));
 
-    if (!env->cpu_breakpoint[index]) {
-        return;
-    }
-    cs = CPU(x86_env_get_cpu(env));
     switch (hw_breakpoint_type(env->dr[7], index)) {
     case DR7_TYPE_BP_INST:
-        if (hw_breakpoint_enabled(env->dr[7], index)) {
+        if (env->cpu_breakpoint[index]) {
             cpu_breakpoint_remove_by_ref(cs, env->cpu_breakpoint[index]);
+            env->cpu_breakpoint[index] = NULL;
         }
         break;
+
     case DR7_TYPE_DATA_WR:
     case DR7_TYPE_DATA_RW:
-        cpu_watchpoint_remove_by_ref(cs, env->cpu_watchpoint[index]);
+        if (env->cpu_breakpoint[index]) {
+            cpu_watchpoint_remove_by_ref(cs, env->cpu_watchpoint[index]);
+            env->cpu_breakpoint[index] = NULL;
+        }
         break;
+
     case DR7_TYPE_IO_RW:
-        /* No support for I/O watchpoints yet */
+        /* HF_IOBPT_MASK cleared elsewhere.  */
         break;
     }
 }
@@ -110,6 +122,7 @@ static void hw_breakpoint_remove(CPUX86State *env, int index)
 void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
 {
     target_ulong old_dr7 = env->dr[7];
+    int iobpt = 0;
     int i;
 
     /* If nothing is changing except the global/local enable bits,
@@ -128,7 +141,10 @@ void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
         env->dr[7] = new_dr7;
         for (i = 0; i < DR7_MAX_BP; i++) {
             if (mod & (2 << i * 2) && hw_breakpoint_enabled(new_dr7, i)) {
-                hw_breakpoint_insert(env, i);
+                iobpt |= hw_breakpoint_insert(env, i);
+            } else if (hw_breakpoint_type(new_dr7, i) == DR7_TYPE_IO_RW
+                       && hw_breakpoint_enabled(new_dr7, i)) {
+                iobpt |= HF_IOBPT_MASK;
             }
         }
     } else {
@@ -137,11 +153,12 @@ void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
         }
         env->dr[7] = new_dr7;
         for (i = 0; i < DR7_MAX_BP; i++) {
-            hw_breakpoint_insert(env, i);
+            iobpt |= hw_breakpoint_insert(env, i);
         }
     }
 
     env->dr[7] |= DR7_FIXED_1;
+    env->hflags = (env->hflags & ~HF_IOBPT_MASK) | iobpt;
 }
 
 static bool check_hw_breakpoints(CPUX86State *env, bool force_dr6_update)
@@ -243,3 +260,30 @@ void helper_movl_drN_T0(CPUX86State *env, int reg, target_ulong t0)
     }
 #endif
 }
+
+/* Check if Port I/O is trapped by a breakpoint.  */
+void helper_bpt_io(CPUX86State *env, uint32_t port,
+                   uint32_t size, target_ulong next_eip)
+{
+#ifndef CONFIG_USER_ONLY
+    target_ulong dr7 = env->dr[7];
+    int i, hit = 0;
+
+    for (i = 0; i < DR7_MAX_BP; ++i) {
+        if (hw_breakpoint_type(dr7, i) == DR7_TYPE_IO_RW
+            && hw_breakpoint_enabled(dr7, i)) {
+            int bpt_len = hw_breakpoint_len(dr7, i);
+            if (port + size - 1 >= env->dr[i]
+                && port <= env->dr[i] + bpt_len - 1) {
+                hit |= 1 << i;
+            }
+        }
+    }
+
+    if (hit) {
+        env->dr[6] = (env->dr[6] & ~0xf) | hit;
+        env->eip = next_eip;
+        raise_exception(env, EXCP01_DB);
+    }
+#endif
+}
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index c9e4edf..649d54a 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -155,6 +155,7 @@
 #define HF_SVMI_SHIFT       21 /* SVM intercepts are active */
 #define HF_OSFXSR_SHIFT     22 /* CR4.OSFXSR */
 #define HF_SMAP_SHIFT       23 /* CR4.SMAP */
+#define HF_IOBPT_SHIFT      24 /* an io breakpoint enabled */
 
 #define HF_CPL_MASK          (3 << HF_CPL_SHIFT)
 #define HF_SOFTMMU_MASK      (1 << HF_SOFTMMU_SHIFT)
@@ -178,6 +179,7 @@
 #define HF_SVMI_MASK         (1 << HF_SVMI_SHIFT)
 #define HF_OSFXSR_MASK       (1 << HF_OSFXSR_SHIFT)
 #define HF_SMAP_MASK         (1 << HF_SMAP_SHIFT)
+#define HF_IOBPT_MASK        (1 << HF_IOBPT_SHIFT)
 
 /* hflags2 */
 
diff --git a/target-i386/helper.h b/target-i386/helper.h
index 8454a04..e9858c0 100644
--- a/target-i386/helper.h
+++ b/target-i386/helper.h
@@ -92,6 +92,7 @@ DEF_HELPER_3(outw, void, env, i32, i32)
 DEF_HELPER_2(inw, tl, env, i32)
 DEF_HELPER_3(outl, void, env, i32, i32)
 DEF_HELPER_2(inl, tl, env, i32)
+DEF_HELPER_FLAGS_4(bpt_io, TCG_CALL_NO_WG, void, env, i32, i32, tl)
 
 DEF_HELPER_3(svm_check_intercept_param, void, env, i32, i64)
 DEF_HELPER_3(vmexit, void, env, i32, i64)
diff --git a/target-i386/translate.c b/target-i386/translate.c
index ef10e68..ceed4d1 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -1154,6 +1154,19 @@ static inline void gen_cmps(DisasContext *s, TCGMemOp ot)
     gen_op_add_reg_T0(s->aflag, R_EDI);
 }
 
+static void gen_bpt_io(DisasContext *s, TCGv_i32 t_port, int ot)
+{
+    if (s->flags & HF_IOBPT_MASK) {
+        TCGv_i32 t_size = tcg_const_i32(1 << ot);
+        TCGv t_next = tcg_const_tl(s->pc - s->cs_base);
+
+        gen_helper_bpt_io(cpu_env, t_port, t_size, t_next);
+        tcg_temp_free_i32(t_size);
+        tcg_temp_free(t_next);
+    }
+}
+
+
 static inline void gen_ins(DisasContext *s, TCGMemOp ot)
 {
     if (s->tb->cflags & CF_USE_ICOUNT) {
@@ -1170,6 +1183,7 @@ static inline void gen_ins(DisasContext *s, TCGMemOp ot)
     gen_op_st_v(s, ot, cpu_T[0], cpu_A0);
     gen_op_movl_T0_Dshift(ot);
     gen_op_add_reg_T0(s->aflag, R_EDI);
+    gen_bpt_io(s, cpu_tmp2_i32, ot);
     if (s->tb->cflags & CF_USE_ICOUNT) {
         gen_io_end();
     }
@@ -1187,9 +1201,9 @@ static inline void gen_outs(DisasContext *s, TCGMemOp ot)
     tcg_gen_andi_i32(cpu_tmp2_i32, cpu_tmp2_i32, 0xffff);
     tcg_gen_trunc_tl_i32(cpu_tmp3_i32, cpu_T[0]);
     gen_helper_out_func(ot, cpu_tmp2_i32, cpu_tmp3_i32);
-
     gen_op_movl_T0_Dshift(ot);
     gen_op_add_reg_T0(s->aflag, R_ESI);
+    gen_bpt_io(s, cpu_tmp2_i32, ot);
     if (s->tb->cflags & CF_USE_ICOUNT) {
         gen_io_end();
     }
@@ -6269,6 +6283,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
         tcg_gen_movi_i32(cpu_tmp2_i32, val);
         gen_helper_in_func(ot, cpu_T[1], cpu_tmp2_i32);
         gen_op_mov_reg_v(ot, R_EAX, cpu_T[1]);
+        gen_bpt_io(s, cpu_tmp2_i32, ot);
         if (s->tb->cflags & CF_USE_ICOUNT) {
             gen_io_end();
             gen_jmp(s, s->pc - s->cs_base);
@@ -6289,6 +6304,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
         tcg_gen_movi_i32(cpu_tmp2_i32, val);
         tcg_gen_trunc_tl_i32(cpu_tmp3_i32, cpu_T[1]);
         gen_helper_out_func(ot, cpu_tmp2_i32, cpu_tmp3_i32);
+        gen_bpt_io(s, cpu_tmp2_i32, ot);
         if (s->tb->cflags & CF_USE_ICOUNT) {
             gen_io_end();
             gen_jmp(s, s->pc - s->cs_base);
@@ -6306,6 +6322,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
         tcg_gen_trunc_tl_i32(cpu_tmp2_i32, cpu_T[0]);
         gen_helper_in_func(ot, cpu_T[1], cpu_tmp2_i32);
         gen_op_mov_reg_v(ot, R_EAX, cpu_T[1]);
+        gen_bpt_io(s, cpu_tmp2_i32, ot);
         if (s->tb->cflags & CF_USE_ICOUNT) {
             gen_io_end();
             gen_jmp(s, s->pc - s->cs_base);
@@ -6325,6 +6342,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
         tcg_gen_trunc_tl_i32(cpu_tmp2_i32, cpu_T[0]);
         tcg_gen_trunc_tl_i32(cpu_tmp3_i32, cpu_T[1]);
         gen_helper_out_func(ot, cpu_tmp2_i32, cpu_tmp3_i32);
+        gen_bpt_io(s, cpu_tmp2_i32, ot);
         if (s->tb->cflags & CF_USE_ICOUNT) {
             gen_io_end();
             gen_jmp(s, s->pc - s->cs_base);
-- 
2.1.0

[Qemu-devel] [PATCH v2 7/9] target-i386: Check CR4[DE] for processing DR4/DR5

[Eduardo Habkost]

From: Richard Henderson <rth@twiddle.net>

Introduce helper_get_dr so that we don't have to put CR4[DE]
into the scarce HFLAGS resource.  At the same time, rename
helper_movl_drN_T0 to helper_set_dr and set the helper flags.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/bpt_helper.c | 46 +++++++++++++++++++++++++++++++++++++++++-----
 target-i386/cpu.h        |  2 +-
 target-i386/helper.h     |  3 ++-
 target-i386/translate.c  | 10 ++++++----
 4 files changed, 50 insertions(+), 11 deletions(-)

diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index 00f3942..3cb4a09 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -241,10 +241,11 @@ void helper_single_step(CPUX86State *env)
     raise_exception(env, EXCP01_DB);
 }
 
-void helper_movl_drN_T0(CPUX86State *env, int reg, target_ulong t0)
+void helper_set_dr(CPUX86State *env, int reg, target_ulong t0)
 {
 #ifndef CONFIG_USER_ONLY
-    if (reg < 4) {
+    switch (reg) {
+    case 0: case 1: case 2: case 3:
         if (hw_breakpoint_enabled(env->dr[7], reg)
             && hw_breakpoint_type(env->dr[7], reg) != DR7_TYPE_IO_RW) {
             hw_breakpoint_remove(env, reg);
@@ -253,14 +254,49 @@ void helper_movl_drN_T0(CPUX86State *env, int reg, target_ulong t0)
         } else {
             env->dr[reg] = t0;
         }
-    } else if (reg == 7) {
+        return;
+    case 4:
+        if (env->cr[4] & CR4_DE_MASK) {
+            break;
+        }
+        /* fallthru */
+    case 6:
+        env->dr[6] = t0;
+        return;
+    case 5:
+        if (env->cr[4] & CR4_DE_MASK) {
+            break;
+        }
+        /* fallthru */
+    case 7:
         cpu_x86_update_dr7(env, t0);
-    } else {
-        env->dr[reg] = t0;
+        return;
     }
+    raise_exception_err_ra(env, EXCP06_ILLOP, 0, GETPC());
 #endif
 }
 
+target_ulong helper_get_dr(CPUX86State *env, int reg)
+{
+    switch (reg) {
+    case 0: case 1: case 2: case 3: case 6: case 7:
+        return env->dr[reg];
+    case 4:
+        if (env->cr[4] & CR4_DE_MASK) {
+            break;
+        } else {
+            return env->dr[6];
+        }
+    case 5:
+        if (env->cr[4] & CR4_DE_MASK) {
+            break;
+        } else {
+            return env->dr[7];
+        }
+    }
+    raise_exception_err_ra(env, EXCP06_ILLOP, 0, GETPC());
+}
+
 /* Check if Port I/O is trapped by a breakpoint.  */
 void helper_bpt_io(CPUX86State *env, uint32_t port,
                    uint32_t size, target_ulong next_eip)
diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 649d54a..f4654f2 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -919,7 +919,7 @@ typedef struct CPUX86State {
     int error_code;
     int exception_is_int;
     target_ulong exception_next_eip;
-    target_ulong dr[8]; /* debug registers */
+    target_ulong dr[8]; /* debug registers; note dr4 and dr5 are unused */
     union {
         struct CPUBreakpoint *cpu_breakpoint[4];
         struct CPUWatchpoint *cpu_watchpoint[4];
diff --git a/target-i386/helper.h b/target-i386/helper.h
index e9858c0..ecfcfd1 100644
--- a/target-i386/helper.h
+++ b/target-i386/helper.h
@@ -40,7 +40,8 @@ DEF_HELPER_2(read_crN, tl, env, int)
 DEF_HELPER_3(write_crN, void, env, int, tl)
 DEF_HELPER_2(lmsw, void, env, tl)
 DEF_HELPER_1(clts, void, env)
-DEF_HELPER_3(movl_drN_T0, void, env, int, tl)
+DEF_HELPER_FLAGS_3(set_dr, TCG_CALL_NO_WG, void, env, int, tl)
+DEF_HELPER_FLAGS_2(get_dr, TCG_CALL_NO_WG, tl, env, int)
 DEF_HELPER_2(invlpg, void, env, tl)
 
 DEF_HELPER_4(enter_level, void, env, int, int, tl)
diff --git a/target-i386/translate.c b/target-i386/translate.c
index ceed4d1..764b1e4 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -7627,18 +7627,20 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
                 ot = MO_64;
             else
                 ot = MO_32;
-            /* XXX: do it dynamically with CR4.DE bit */
-            if (reg == 4 || reg == 5 || reg >= 8)
+            if (reg >= 8) {
                 goto illegal_op;
+            }
             if (b & 2) {
                 gen_svm_check_intercept(s, pc_start, SVM_EXIT_WRITE_DR0 + reg);
                 gen_op_mov_v_reg(ot, cpu_T[0], rm);
-                gen_helper_movl_drN_T0(cpu_env, tcg_const_i32(reg), cpu_T[0]);
+                tcg_gen_movi_i32(cpu_tmp2_i32, reg);
+                gen_helper_set_dr(cpu_env, cpu_tmp2_i32, cpu_T[0]);
                 gen_jmp_im(s->pc - s->cs_base);
                 gen_eob(s);
             } else {
                 gen_svm_check_intercept(s, pc_start, SVM_EXIT_READ_DR0 + reg);
-                tcg_gen_ld_tl(cpu_T[0], cpu_env, offsetof(CPUX86State,dr[reg]));
+                tcg_gen_movi_i32(cpu_tmp2_i32, reg);
+                gen_helper_get_dr(cpu_T[0], cpu_env, cpu_tmp2_i32);
                 gen_op_mov_reg_v(ot, rm, cpu_T[0]);
             }
         }
-- 
2.1.0

[Qemu-devel] [PATCH v2 8/9] target-i386: Ensure always-1 bits on DR6 can't be cleared

[Eduardo Habkost]

Bits 4-11 and 16-31 on DR6 are documented as always 1, so ensure they
can't be cleared by software.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/bpt_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
index 3cb4a09..0fbdc03 100644
--- a/target-i386/bpt_helper.c
+++ b/target-i386/bpt_helper.c
@@ -261,7 +261,7 @@ void helper_set_dr(CPUX86State *env, int reg, target_ulong t0)
         }
         /* fallthru */
     case 6:
-        env->dr[6] = t0;
+        env->dr[6] = t0 | DR6_FIXED_1;
         return;
     case 5:
         if (env->cr[4] & CR4_DE_MASK) {
-- 
2.1.0

[Qemu-devel] [PATCH v2 9/9] target-i386: Add DE to TCG_FEATURES

[Eduardo Habkost]

Now DE is supported by TCG so it can be enabled in CPUID bits.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target-i386/cpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 05d7f26..5fe49b5 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -312,7 +312,7 @@ static const char *cpuid_6_feature_name[] = {
           CPUID_PAE | CPUID_MCE | CPUID_CX8 | CPUID_APIC | CPUID_SEP | \
           CPUID_MTRR | CPUID_PGE | CPUID_MCA | CPUID_CMOV | CPUID_PAT | \
           CPUID_PSE36 | CPUID_CLFLUSH | CPUID_ACPI | CPUID_MMX | \
-          CPUID_FXSR | CPUID_SSE | CPUID_SSE2 | CPUID_SS)
+          CPUID_FXSR | CPUID_SSE | CPUID_SSE2 | CPUID_SS | CPUID_DE)
           /* partly implemented:
           CPUID_MTRR, CPUID_MCA, CPUID_CLFLUSH (needed for Win64) */
           /* missing:
-- 
2.1.0

Re: [Qemu-devel] [PATCH v2 3/9] target-i386: Ensure bit 10 on DR7 is never cleared

[Richard Henderson]

On 10/16/2015 06:23 AM, Eduardo Habkost wrote:
> Bit 10 of DR7 is documented as always set to 1, so ensure that's
> always the case.
>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>   target-i386/bpt_helper.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
> index 23ce828..493deba 100644
> --- a/target-i386/bpt_helper.c
> +++ b/target-i386/bpt_helper.c
> @@ -113,6 +113,8 @@ void cpu_x86_update_dr7(CPUX86State *env, uint32_t new_dr7)
>               hw_breakpoint_insert(env, i);
>           }
>       }
> +
> +    env->dr[7] |= DR7_FIXED_1;

Better to do this to new_dr7, above the xor test with old_dr7, so that we still 
pass the xor test.


r~

Re: [Qemu-devel] [PATCH v2 8/9] target-i386: Ensure always-1 bits on DR6 can't be cleared

[Richard Henderson]

On 10/16/2015 06:23 AM, Eduardo Habkost wrote:
> Bits 4-11 and 16-31 on DR6 are documented as always 1, so ensure they
> can't be cleared by software.
>
> Signed-off-by: Eduardo Habkost<ehabkost@redhat.com>
> ---
>   target-i386/bpt_helper.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~

Re: [Qemu-devel] [PATCH v2 9/9] target-i386: Add DE to TCG_FEATURES

[Richard Henderson]

On 10/16/2015 06:23 AM, Eduardo Habkost wrote:
> Now DE is supported by TCG so it can be enabled in CPUID bits.
>
> Signed-off-by: Eduardo Habkost<ehabkost@redhat.com>
> ---
>   target-i386/cpu.c | 2 +-

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~

Re: [Qemu-devel] [PATCH v2 6/9] target-i386: Handle I/O breakpoints

[Eduardo Habkost]

On Fri, Oct 16, 2015 at 01:23:36PM -0300, Eduardo Habkost wrote:
> From: Richard Henderson <rth@twiddle.net>
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> Changes v1 -> v2:
> * Rebase on top of new version of "Re-introduce optimal breakpoint
>   removal"
> ---
>  target-i386/bpt_helper.c | 98 +++++++++++++++++++++++++++++++++++-------------
>  target-i386/cpu.h        |  2 +
>  target-i386/helper.h     |  1 +
>  target-i386/translate.c  | 20 +++++++++-
>  4 files changed, 93 insertions(+), 28 deletions(-)
> 
> diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
> index 0563abd..00f3942 100644
> --- a/target-i386/bpt_helper.c
> +++ b/target-i386/bpt_helper.c
> @@ -49,60 +49,72 @@ static inline int hw_breakpoint_len(unsigned long dr7, int index)
>      return (len == 2) ? 8 : len + 1;
>  }
>  
> -static void hw_breakpoint_insert(CPUX86State *env, int index)
> +static int hw_breakpoint_insert(CPUX86State *env, int index)
>  {
>      CPUState *cs = CPU(x86_env_get_cpu(env));
> -    int type = 0, err = 0;
> +    target_ulong dr7 = env->dr[7];
> +    target_ulong drN = env->dr[index];
> +    int err = 0;
>  
> -    switch (hw_breakpoint_type(env->dr[7], index)) {
> +    switch (hw_breakpoint_type(dr7, index)) {
>      case DR7_TYPE_BP_INST:
> -        if (hw_breakpoint_enabled(env->dr[7], index)) {
> -            err = cpu_breakpoint_insert(cs, env->dr[index], BP_CPU,
> +        if (hw_breakpoint_enabled(dr7, index)) {
> +            err = cpu_breakpoint_insert(cs, drN, BP_CPU,
>                                          &env->cpu_breakpoint[index]);
>          }
>          break;
> -    case DR7_TYPE_DATA_WR:
> -        type = BP_CPU | BP_MEM_WRITE;
> -        break;
> +
>      case DR7_TYPE_IO_RW:
> -        /* No support for I/O watchpoints yet */
> +        /* Notice when we should enable calls to bpt_io.  */
> +        return (hw_breakpoint_enabled(env->dr[7], index)
> +                ? HF_IOBPT_MASK : 0);

checkpatch.pl error:

  ERROR: return is not a function, parentheses are not required
  #57: FILE: target-i386/bpt_helper.c:69:
  +        return (hw_breakpoint_enabled(env->dr[7], index)
  
  total: 1 errors, 0 warnings, 242 lines checked

I will fix it in v3.

-- 
Eduardo

Re: [Qemu-devel] [PATCH v2 6/9] target-i386: Handle I/O breakpoints

[Richard Henderson]

On 10/19/2015 07:30 AM, Eduardo Habkost wrote:
>> >+        /* Notice when we should enable calls to bpt_io.  */
>> >+        return (hw_breakpoint_enabled(env->dr[7], index)
>> >+                ? HF_IOBPT_MASK : 0);
> checkpatch.pl error:
>
>    ERROR: return is not a function, parentheses are not required
>    #57: FILE: target-i386/bpt_helper.c:69:
>    +        return (hw_breakpoint_enabled(env->dr[7], index)
>
>    total: 1 errors, 0 warnings, 242 lines checked
>
> I will fix it in v3.

In this case checkpatch is wrong, imo.  The parenthesis are not there to "make 
return a function", but to make the multi-line expression indent properly.


r~

Re: [Qemu-devel] [PATCH v2 6/9] target-i386: Handle I/O breakpoints

[Eduardo Habkost]

On Mon, Oct 19, 2015 at 07:46:51AM -1000, Richard Henderson wrote:
> On 10/19/2015 07:30 AM, Eduardo Habkost wrote:
> >>>+        /* Notice when we should enable calls to bpt_io.  */
> >>>+        return (hw_breakpoint_enabled(env->dr[7], index)
> >>>+                ? HF_IOBPT_MASK : 0);
> >checkpatch.pl error:
> >
> >   ERROR: return is not a function, parentheses are not required
> >   #57: FILE: target-i386/bpt_helper.c:69:
> >   +        return (hw_breakpoint_enabled(env->dr[7], index)
> >
> >   total: 1 errors, 0 warnings, 242 lines checked
> >
> >I will fix it in v3.
> 
> In this case checkpatch is wrong, imo.  The parenthesis are not there to
> "make return a function", but to make the multi-line expression indent
> properly.

I understand if one thinks the expression looks better with the parenthesis,
but I fail to see why they are needed to indent the expression properly.

For reference, this is the change I have made in v3:

    diff --git a/target-i386/bpt_helper.c b/target-i386/bpt_helper.c
    index 0fbdc03..dac1b1a 100644
    --- a/target-i386/bpt_helper.c
    +++ b/target-i386/bpt_helper.c
    @@ -66,8 +66,8 @@ static int hw_breakpoint_insert(CPUX86State *env, int index)
    
         case DR7_TYPE_IO_RW:
             /* Notice when we should enable calls to bpt_io.  */
    -        return (hw_breakpoint_enabled(env->dr[7], index)
    -                ? HF_IOBPT_MASK : 0);
    +        return hw_breakpoint_enabled(env->dr[7], index)
    +               ? HF_IOBPT_MASK : 0;
    
         case DR7_TYPE_DATA_WR:
             if (hw_breakpoint_enabled(dr7, index)) {

-- 
Eduardo

Re: [Qemu-devel] [PATCH v2 6/9] target-i386: Handle I/O breakpoints

[Paolo Bonzini]

On 19/10/2015 19:57, Eduardo Habkost wrote:
> On Mon, Oct 19, 2015 at 07:46:51AM -1000, Richard Henderson wrote:
>> On 10/19/2015 07:30 AM, Eduardo Habkost wrote:
>>>>> +        /* Notice when we should enable calls to bpt_io.  */
>>>>> +        return (hw_breakpoint_enabled(env->dr[7], index)
>>>>> +                ? HF_IOBPT_MASK : 0);
>>> checkpatch.pl error:
>>>
>>>   ERROR: return is not a function, parentheses are not required
>>>   #57: FILE: target-i386/bpt_helper.c:69:
>>>   +        return (hw_breakpoint_enabled(env->dr[7], index)
>>>
>>>   total: 1 errors, 0 warnings, 242 lines checked
>>>
>>> I will fix it in v3.
>>
>> In this case checkpatch is wrong, imo.  The parenthesis are not there to
>> "make return a function", but to make the multi-line expression indent
>> properly.
> 
> I understand if one thinks the expression looks better with the parenthesis,
> but I fail to see why they are needed to indent the expression properly.

Because Emacs indents this:

>     +        return hw_breakpoint_enabled(env->dr[7], index)
>     +               ? HF_IOBPT_MASK : 0;

with the ? under the second "r" of "return", while it indents this as
written:

>     -        return (hw_breakpoint_enabled(env->dr[7], index)
>     -                ? HF_IOBPT_MASK : 0);

Another random example:

static bool sdl_check_format(DisplayChangeListener *dcl,
                             pixman_format_code_t format)
{
    /*
     * We let SDL convert for us a few more formats than,
     * the native ones. Thes are the ones I have tested.
     */
    return (format == PIXMAN_x8r8g8b8 ||
            format == PIXMAN_b8g8r8x8 ||
            format == PIXMAN_x1r5g5b5 ||
            format == PIXMAN_r5g6b5);
}

There's no unanimity though, so your v3 is okay too.

Paolo