Commit 202126dcb9 for qemu.org

commit 202126dcb9d6261c38e629799265defeb3260d25
Author: Eric Auger <eric.auger@redhat.com>
Date:   Mon Apr 20 16:03:57 2026 +0200

    Revert "target/arm: Reinstate bogus AArch32 DBGDTRTX register for migration compat"

    This reverts commit 4f2b82f60431 ("target/arm: Reinstate bogus AArch32
    DBGDTRTX register for migration compat). We don't need that commit
    anymore as the AArch32 DBGDTRTX register is declared to
    be safe to ignore in the incoming migration stream.

    Signed-off-by: Eric Auger <eric.auger@redhat.com>
    Reviewed-by: Sebastian Ott <sebott@redhat.com>
    Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
    Message-id: 20260420140552.104369-8-eric.auger@redhat.com
    Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target/arm/debug_helper.c b/target/arm/debug_helper.c
index 352c8e5c8e..8477ca5def 100644
--- a/target/arm/debug_helper.c
+++ b/target/arm/debug_helper.c
@@ -171,13 +171,6 @@ static void dbgclaimclr_write(CPUARMState *env, const ARMCPRegInfo *ri,
     env->cp15.dbgclaim &= ~(value & 0xFF);
 }

-static CPAccessResult access_bogus(CPUARMState *env, const ARMCPRegInfo *ri,
-                                   bool isread)
-{
-    /* Always UNDEF, as if this cpreg didn't exist */
-    return CP_ACCESS_UNDEFINED;
-}
-
 static const ARMCPRegInfo debug_cp_reginfo[] = {
     /*
      * DBGDRAR, DBGDSAR: always RAZ since we don't implement memory mapped
@@ -240,28 +233,6 @@ static const ARMCPRegInfo debug_cp_reginfo[] = {
       .opc0 = 2, .opc1 = 3, .crn = 0, .crm = 4, .opc2 = 0,
       .access = PL0_RW, .accessfn = access_tdcc,
       .type = ARM_CP_CONST, .resetvalue = 0 },
-    /*
-     * This is not a real AArch32 register. We used to incorrectly expose
-     * this due to a QEMU bug; to avoid breaking migration compatibility we
-     * need to continue to provide it so that we don't fail the inbound
-     * migration when it tells us about a sysreg that we don't have.
-     * We set an always-fails .accessfn, which means that the guest doesn't
-     * actually see this register (it will always UNDEF, identically to if
-     * there were no cpreg definition for it other than that we won't print
-     * a LOG_UNIMP message about it), and we set the ARM_CP_NO_GDB flag so the
-     * gdbstub won't see it either.
-     * (We can't just set .access = 0, because add_cpreg_to_hashtable()
-     * helpfully ignores cpregs which aren't accessible to the highest
-     * implemented EL.)
-     *
-     * TODO: implement a system for being able to describe "this register
-     * can be ignored if it appears in the inbound stream"; then we can
-     * remove this temporary hack.
-     */
-    { .name = "BOGUS_DBGDTR_EL0", .state = ARM_CP_STATE_AA32,
-      .cp = 14, .opc1 = 3, .crn = 0, .crm = 5, .opc2 = 0,
-      .access = PL0_RW, .accessfn = access_bogus,
-      .type = ARM_CP_CONST | ARM_CP_NO_GDB, .resetvalue = 0 },
     /*
      * OSECCR_EL1 provides a mechanism for an operating system
      * to access the contents of EDECCR. EDECCR is not implemented though,