target/arm: Redirect VHE FOO_EL1 -> FOO_EL2 during translation

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Author: rth7680

target/arm/cpregs.h

@@ -936,6 +936,12 @@ struct ARMCPRegInfo {
      */
     uint32_t nv2_redirect_offset;
 
+    /*
+     * With VHE, with E2H, at EL2, access to this EL0/EL1 reg redirects
+     * to the EL2 reg with the specified key.
+     */
+    uint32_t vhe_redir_to_el2;
+
     /* This is used only by VHE. */
     void *opaque;
     /*

target/arm/gdbstub.c

@@ -249,6 +249,11 @@ static int arm_gdb_get_sysreg(CPUState *cs, GByteArray *buf, int reg)
     if (ri) {
         switch (cpreg_field_type(ri)) {
         case MO_64:
+            if (ri->vhe_redir_to_el2 &&
+                (arm_hcr_el2_eff(env) & HCR_E2H) &&
+                arm_current_el(env) == 2) {
+                ri = get_arm_cp_reginfo(cpu->cp_regs, ri->vhe_redir_to_el2);
+            }
             return gdb_get_reg64(buf, (uint64_t)read_raw_cp_reg(env, ri));
         case MO_32:
             return gdb_get_reg32(buf, (uint32_t)read_raw_cp_reg(env, ri));

target/arm/helper.c

@@ -4417,47 +4417,6 @@ static CPAccessResult access_el1nvvct(CPUARMState *env, const ARMCPRegInfo *ri,
     return e2h_access(env, ri, isread);
 }
 
-/* Test if system register redirection is to occur in the current state.  */
-static bool redirect_for_e2h(CPUARMState *env)
-{
-    return arm_current_el(env) == 2 && (arm_hcr_el2_eff(env) & HCR_E2H);
-}
-
-static uint64_t el2_e2h_read(CPUARMState *env, const ARMCPRegInfo *ri)
-{
-    CPReadFn *readfn;
-
-    if (redirect_for_e2h(env)) {
-        /* Switch to the saved EL2 version of the register.  */
-        ri = ri->opaque;
-        readfn = ri->readfn;
-    } else {
-        readfn = ri->orig_readfn;
-    }
-    if (readfn == NULL) {
-        readfn = raw_read;
-    }
-    return readfn(env, ri);
-}
-
-static void el2_e2h_write(CPUARMState *env, const ARMCPRegInfo *ri,
-                          uint64_t value)
-{
-    CPWriteFn *writefn;
-
-    if (redirect_for_e2h(env)) {
-        /* Switch to the saved EL2 version of the register.  */
-        ri = ri->opaque;
-        writefn = ri->writefn;
-    } else {
-        writefn = ri->orig_writefn;
-    }
-    if (writefn == NULL) {
-        writefn = raw_write;
-    }
-    writefn(env, ri, value);
-}
-
 static uint64_t el2_e2h_e12_read(CPUARMState *env, const ARMCPRegInfo *ri)
 {
     /* Pass the EL1 register accessor its ri, not the EL12 alias ri */
@@ -4632,17 +4591,7 @@ static void define_arm_vh_e2h_redirects_aliases(ARMCPU *cpu)
                                  (gpointer)(uintptr_t)a->new_key, new_reg);
         g_assert(ok);
 
-        src_reg->opaque = dst_reg;
-        src_reg->orig_readfn = src_reg->readfn ?: raw_read;
-        src_reg->orig_writefn = src_reg->writefn ?: raw_write;
-        if (!src_reg->raw_readfn) {
-            src_reg->raw_readfn = raw_read;
-        }
-        if (!src_reg->raw_writefn) {
-            src_reg->raw_writefn = raw_write;
-        }
-        src_reg->readfn = el2_e2h_read;
-        src_reg->writefn = el2_e2h_write;
+        src_reg->vhe_redir_to_el2 = a->dst_key;
     }
 }
 #endif

target/arm/tcg/translate-a64.c

@@ -2573,6 +2573,15 @@ static void handle_sys(DisasContext *s, bool isread,
         }
     }
 
+    if (ri->vhe_redir_to_el2 && s->current_el == 2 && s->e2h) {
+        /*
+         * This one of the FOO_EL1 registers which redirect to FOO_EL2
+         * from EL2 when HCR_EL2.E2H is set.
+         */
+        key = ri->vhe_redir_to_el2;
+        ri = redirect_cpreg(s, key, isread);
+    }
+
     if (ri->accessfn || (ri->fgt && s->fgt_active)) {
         /* Emit code to perform further access permissions checks at
          * runtime; this may result in an exception.