[PATCH v6 1/4] accel/tcg: Add probe_access_range_flags interface

[Daniel Henrique Barboza <dbarboza@ventanamicro.com>]

From: Christoph Muellner <cmuellner@linux.com>

The existing probe_access* functions do not allow to specify the
access size and a non-faulting behavior at the same time.

This is resolved by adding a generalization of probe_access_flags()
that takes an additional size parameter.

The semantics is basically the same as probe_access_flags(),
but instead of assuming an access to any byte of the addressed
page, we can restrict to access to a specific area, like
probe_access() allows.

Signed-off-by: Christoph Muellner <cmuellner@linux.com>
---
 accel/tcg/cputlb.c      | 19 +++++++++++++++++++
 accel/tcg/user-exec.c   | 15 ++++++++++++---
 include/exec/exec-all.h | 24 ++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
index 4812d83961..dd3bc7a356 100644
--- a/accel/tcg/cputlb.c
+++ b/accel/tcg/cputlb.c
@@ -1606,6 +1606,25 @@ int probe_access_full(CPUArchState *env, target_ulong addr,
     return flags;
 }
 
+int probe_access_range_flags(CPUArchState *env, target_ulong addr,
+                             int size, MMUAccessType access_type,
+                             int mmu_idx, bool nonfault, void **phost,
+                             uintptr_t retaddr)
+{
+    CPUTLBEntryFull *full;
+    int flags = probe_access_internal(env, addr, size, access_type,
+                                      mmu_idx, nonfault, phost, &full,
+                                      retaddr);
+
+    /* Handle clean RAM pages.  */
+    if (unlikely(flags & TLB_NOTDIRTY)) {
+        notdirty_write(env_cpu(env), addr, 1, full, retaddr);
+        flags &= ~TLB_NOTDIRTY;
+    }
+
+    return flags;
+}
+
 int probe_access_flags(CPUArchState *env, target_ulong addr,
                        MMUAccessType access_type, int mmu_idx,
                        bool nonfault, void **phost, uintptr_t retaddr)
diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index ae67d84638..a73c840655 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -761,9 +761,10 @@ static int probe_access_internal(CPUArchState *env, target_ulong addr,
     cpu_loop_exit_sigsegv(env_cpu(env), addr, access_type, maperr, ra);
 }
 
-int probe_access_flags(CPUArchState *env, target_ulong addr,
-                       MMUAccessType access_type, int mmu_idx,
-                       bool nonfault, void **phost, uintptr_t ra)
+int probe_access_range_flags(CPUArchState *env, target_ulong addr,
+                             int size, MMUAccessType access_type,
+                             int mmu_idx, bool nonfault, void **phost,
+                             uintptr_t ra)
 {
     int flags;
 
@@ -772,6 +773,14 @@ int probe_access_flags(CPUArchState *env, target_ulong addr,
     return flags;
 }
 
+int probe_access_flags(CPUArchState *env, target_ulong addr,
+                       MMUAccessType access_type, int mmu_idx,
+                       bool nonfault, void **phost, uintptr_t ra)
+{
+    return probe_access_range_flags(env, addr, 0, access_type, mmu_idx,
+                                    nonfault, phost, ra);
+}
+
 void *probe_access(CPUArchState *env, target_ulong addr, int size,
                    MMUAccessType access_type, int mmu_idx, uintptr_t ra)
 {
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 54585a9954..b75f15f247 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -442,6 +442,30 @@ static inline void *probe_read(CPUArchState *env, target_ulong addr, int size,
     return probe_access(env, addr, size, MMU_DATA_LOAD, mmu_idx, retaddr);
 }
 
+/**
+ * probe_access_range_flags:
+ * @env: CPUArchState
+ * @addr: guest virtual address to look up
+ * @size: size of the access
+ * @access_type: read, write or execute permission
+ * @mmu_idx: MMU index to use for lookup
+ * @nonfault: suppress the fault
+ * @phost: return value for host address
+ * @retaddr: return address for unwinding
+ *
+ * Similar to probe_access, loosely returning the TLB_FLAGS_MASK for
+ * the access range, and storing the host address for RAM in @phost.
+ *
+ * If @nonfault is set, do not raise an exception but return TLB_INVALID_MASK.
+ * Do not handle watchpoints, but include TLB_WATCHPOINT in the returned flags.
+ * Do handle clean pages, so exclude TLB_NOTDIRTY from the returned flags.
+ * For simplicity, all "mmio-like" flags are folded to TLB_MMIO.
+ */
+int probe_access_range_flags(CPUArchState *env, target_ulong addr,
+                             int size, MMUAccessType access_type,
+                             int mmu_idx, bool nonfault, void **phost,
+                             uintptr_t retaddr);
+
 /**
  * probe_access_flags:
  * @env: CPUArchState
-- 
2.39.2