[PATCH v3 0/2] arm: move DCZID_EL0 to idregs array

[PATCH v3 0/2] arm: move DCZID_EL0 to idregs array

[Cornelia Huck]

This is part of the ongoing effort to move all id registers to the idregs
array (so that we can work with an autogenerated list of registers.)

Changes v2->v3:
- separate patch for adding the helpers
- put some rationale into the patch description

Cornelia Huck (2):
  arm: add {get,set}_dczid_bs helpers
  arm: add DCZID_EL0 to idregs array

 target/arm/cpu-sysregs.h.inc   |  1 +
 target/arm/cpu.c               |  2 +-
 target/arm/cpu.h               | 14 ++++++++++++--
 target/arm/cpu64.c             |  4 ++--
 target/arm/helper.c            |  5 ++++-
 target/arm/tcg/cpu64.c         | 22 +++++++++++-----------
 target/arm/tcg/helper-a64.c    |  2 +-
 target/arm/tcg/mte_helper.c    |  4 ++--
 target/arm/tcg/translate-a64.c |  2 +-
 target/arm/tcg/translate.h     |  2 +-
 10 files changed, 36 insertions(+), 22 deletions(-)

-- 
2.52.0

[PATCH v3 1/2] arm: add {get,set}_dczid_bs helpers

[Cornelia Huck]

Most accesses to cpu->dcz_blocksize really care about
DCZID_EL0.BS (i.e. the part of the register that does not change at
different EL.) Wean them off directly dealing with cpu->dcz_blocksize
so that we can switch to handling DCZID_EL0 differently in a followup
patch.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---
 target/arm/cpu.c               |  2 +-
 target/arm/cpu.h               | 10 ++++++++++
 target/arm/cpu64.c             |  4 ++--
 target/arm/helper.c            |  1 +
 target/arm/tcg/cpu64.c         | 22 +++++++++++-----------
 target/arm/tcg/helper-a64.c    |  2 +-
 target/arm/tcg/mte_helper.c    |  4 ++--
 target/arm/tcg/translate-a64.c |  2 +-
 8 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/target/arm/cpu.c b/target/arm/cpu.c
index caf7980b1fc5..59e4c4f6fc2e 100644
--- a/target/arm/cpu.c
+++ b/target/arm/cpu.c
@@ -2184,7 +2184,7 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
 #endif
 
     if (tcg_enabled()) {
-        int dcz_blocklen = 4 << cpu->dcz_blocksize;
+        int dcz_blocklen = 4 << get_dczid_bs(cpu);
 
         /*
          * We only support DCZ blocklen that fits on one page.
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 9579d43ba338..c0dae1a891a7 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1178,6 +1178,16 @@ struct ARMCPUClass {
     ResettablePhases parent_phases;
 };
 
+static inline uint8_t get_dczid_bs(ARMCPU *cpu)
+{
+    return cpu->dcz_blocksize;
+}
+
+static inline void set_dczid_bs(ARMCPU *cpu, uint8_t bs)
+{
+    cpu->dcz_blocksize = bs;
+}
+
 /* Callback functions for the generic timer's timers. */
 void arm_gt_ptimer_cb(void *opaque);
 void arm_gt_vtimer_cb(void *opaque);
diff --git a/target/arm/cpu64.c b/target/arm/cpu64.c
index bf3038137019..4dfc03973e17 100644
--- a/target/arm/cpu64.c
+++ b/target/arm/cpu64.c
@@ -689,7 +689,7 @@ static void aarch64_a57_initfn(Object *obj)
     cpu->ccsidr[1] = make_ccsidr(CCSIDR_FORMAT_LEGACY, 3, 64, 48 * KiB, 2);
     /* 2048KB L2 cache */
     cpu->ccsidr[2] = make_ccsidr(CCSIDR_FORMAT_LEGACY, 16, 64, 2 * MiB, 7);
-    cpu->dcz_blocksize = 4; /* 64 bytes */
+    set_dczid_bs(cpu, 4); /* 64 bytes */
     cpu->gic_num_lrs = 4;
     cpu->gic_vpribits = 5;
     cpu->gic_vprebits = 5;
@@ -751,7 +751,7 @@ static void aarch64_a53_initfn(Object *obj)
     cpu->ccsidr[1] = make_ccsidr(CCSIDR_FORMAT_LEGACY, 1, 64, 32 * KiB, 2);
     /* 1024KB L2 cache */
     cpu->ccsidr[2] = make_ccsidr(CCSIDR_FORMAT_LEGACY, 16, 64, 1 * MiB, 7);
-    cpu->dcz_blocksize = 4; /* 64 bytes */
+    set_dczid_bs(cpu, 4); /* 64 bytes */
     cpu->gic_num_lrs = 4;
     cpu->gic_vpribits = 5;
     cpu->gic_vprebits = 5;
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 263ca29d92b4..61b3b90b63c0 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -3324,6 +3324,7 @@ static uint64_t aa64_dczid_read(CPUARMState *env, const ARMCPRegInfo *ri)
     if (aa64_zva_access(env, NULL, false) == CP_ACCESS_OK) {
         dzp_bit = 0;
     }
+
     return cpu->dcz_blocksize | dzp_bit;
 }
 
diff --git a/target/arm/tcg/cpu64.c b/target/arm/tcg/cpu64.c
index 917db5bb09a0..3db8d4694a7d 100644
--- a/target/arm/tcg/cpu64.c
+++ b/target/arm/tcg/cpu64.c
@@ -72,7 +72,7 @@ static void aarch64_a35_initfn(Object *obj)
     SET_IDREG(isar, ID_AA64MMFR0, 0x00101122);
     SET_IDREG(isar, ID_AA64MMFR1, 0);
     SET_IDREG(isar, CLIDR, 0x0a200023);
-    cpu->dcz_blocksize = 4;
+    set_dczid_bs(cpu, 4);
 
     /* From B2.4 AArch64 Virtual Memory control registers */
     cpu->reset_sctlr = 0x00c50838;
@@ -219,7 +219,7 @@ static void aarch64_a55_initfn(Object *obj)
     /* Ordered by B2.4 AArch64 registers by functional group */
     SET_IDREG(isar, CLIDR, 0x82000023);
     cpu->ctr = 0x84448004; /* L1Ip = VIPT */
-    cpu->dcz_blocksize = 4; /* 64 bytes */
+    set_dczid_bs(cpu, 4); /* 64 bytes */
     SET_IDREG(isar, ID_AA64DFR0, 0x0000000010305408ull);
     SET_IDREG(isar, ID_AA64ISAR0, 0x0000100010211120ull);
     SET_IDREG(isar, ID_AA64ISAR1, 0x0000000000100001ull);
@@ -325,7 +325,7 @@ static void aarch64_a72_initfn(Object *obj)
     cpu->ccsidr[1] = make_ccsidr(CCSIDR_FORMAT_LEGACY, 3, 64, 48 * KiB, 2);
     /* 1MB L2 cache */
     cpu->ccsidr[2] = make_ccsidr(CCSIDR_FORMAT_LEGACY, 16, 64, 1 * MiB, 7);
-    cpu->dcz_blocksize = 4; /* 64 bytes */
+    set_dczid_bs(cpu, 4); /* 64 bytes */
     cpu->gic_num_lrs = 4;
     cpu->gic_vpribits = 5;
     cpu->gic_vprebits = 5;
@@ -352,7 +352,7 @@ static void aarch64_a76_initfn(Object *obj)
     /* Ordered by B2.4 AArch64 registers by functional group */
     SET_IDREG(isar, CLIDR, 0x82000023);
     cpu->ctr = 0x8444C004;
-    cpu->dcz_blocksize = 4;
+    set_dczid_bs(cpu, 4);
     SET_IDREG(isar, ID_AA64DFR0, 0x0000000010305408ull);
     SET_IDREG(isar, ID_AA64ISAR0, 0x0000100010211120ull);
     SET_IDREG(isar, ID_AA64ISAR1, 0x0000000000100001ull);
@@ -424,7 +424,7 @@ static void aarch64_a78ae_initfn(Object *obj)
     /* Ordered by 3.2.4 AArch64 registers by functional group */
     SET_IDREG(isar, CLIDR, 0x82000023);
     cpu->ctr = 0x9444c004;
-    cpu->dcz_blocksize = 4;
+    set_dczid_bs(cpu, 4);
     SET_IDREG(isar, ID_AA64DFR0, 0x0000000110305408ull);
     SET_IDREG(isar, ID_AA64ISAR0, 0x0010100010211120ull);
     SET_IDREG(isar, ID_AA64ISAR1, 0x0000000001200031ull);
@@ -517,7 +517,7 @@ static void aarch64_a64fx_initfn(Object *obj)
     cpu->ccsidr[1] = make_ccsidr(CCSIDR_FORMAT_LEGACY, 4, 256, 64 * KiB, 2);
     /* 8MB L2 cache */
     cpu->ccsidr[2] = make_ccsidr(CCSIDR_FORMAT_LEGACY, 16, 256, 8 * MiB, 7);
-    cpu->dcz_blocksize = 6; /* 256 bytes */
+    set_dczid_bs(cpu, 6); /* 256 bytes */
     cpu->gic_num_lrs = 4;
     cpu->gic_vpribits = 5;
     cpu->gic_vprebits = 5;
@@ -673,7 +673,7 @@ static void aarch64_neoverse_n1_initfn(Object *obj)
     /* Ordered by B2.4 AArch64 registers by functional group */
     SET_IDREG(isar, CLIDR, 0x82000023);
     cpu->ctr = 0x8444c004;
-    cpu->dcz_blocksize = 4;
+    set_dczid_bs(cpu, 4);
     SET_IDREG(isar, ID_AA64DFR0, 0x0000000110305408ull);
     SET_IDREG(isar, ID_AA64ISAR0, 0x0000100010211120ull);
     SET_IDREG(isar, ID_AA64ISAR1, 0x0000000000100001ull);
@@ -749,7 +749,7 @@ static void aarch64_neoverse_v1_initfn(Object *obj)
     /* Ordered by 3.2.4 AArch64 registers by functional group */
     SET_IDREG(isar, CLIDR, 0x82000023);
     cpu->ctr = 0xb444c004; /* With DIC and IDC set */
-    cpu->dcz_blocksize = 4;
+    set_dczid_bs(cpu, 4);
     SET_IDREG(isar, ID_AA64AFR0, 0x00000000);
     SET_IDREG(isar, ID_AA64AFR1, 0x00000000);
     SET_IDREG(isar, ID_AA64DFR0, 0x000001f210305519ull);
@@ -1011,7 +1011,7 @@ static void aarch64_a710_initfn(Object *obj)
     SET_IDREG(isar, CLIDR, 0x0000001482000023ull);
     cpu->gm_blocksize      = 4;
     cpu->ctr               = 0x000000049444c004ull;
-    cpu->dcz_blocksize     = 4;
+    set_dczid_bs(cpu, 4);
     /* TODO FEAT_MPAM: mpamidr_el1 = 0x0000_0001_0006_003f */
 
     /* Section B.5.2: PMCR_EL0 */
@@ -1113,7 +1113,7 @@ static void aarch64_neoverse_n2_initfn(Object *obj)
     SET_IDREG(isar, CLIDR, 0x0000001482000023ull);
     cpu->gm_blocksize      = 4;
     cpu->ctr               = 0x00000004b444c004ull;
-    cpu->dcz_blocksize     = 4;
+    set_dczid_bs(cpu, 4);
     /* TODO FEAT_MPAM: mpamidr_el1 = 0x0000_0001_001e_01ff */
 
     /* Section B.7.2: PMCR_EL0 */
@@ -1377,7 +1377,7 @@ void aarch64_max_tcg_initfn(Object *obj)
      * blocksize since we don't have to follow what the hardware does.
      */
     cpu->ctr = 0x80038003; /* 32 byte I and D cacheline size, VIPT icache */
-    cpu->dcz_blocksize = 7; /*  512 bytes */
+    set_dczid_bs(cpu, 7); /*  512 bytes */
 #endif
     cpu->gm_blocksize = 6;  /*  256 bytes */
 
diff --git a/target/arm/tcg/helper-a64.c b/target/arm/tcg/helper-a64.c
index ba1d775d818e..e4d2c2e3928c 100644
--- a/target/arm/tcg/helper-a64.c
+++ b/target/arm/tcg/helper-a64.c
@@ -792,7 +792,7 @@ void HELPER(dc_zva)(CPUARMState *env, uint64_t vaddr_in)
      * (which matches the usual QEMU behaviour of not implementing either
      * alignment faults or any memory attribute handling).
      */
-    int blocklen = 4 << env_archcpu(env)->dcz_blocksize;
+    int blocklen = 4 << get_dczid_bs(env_archcpu(env));
     uint64_t vaddr = vaddr_in & ~(blocklen - 1);
     int mmu_idx = arm_env_mmu_index(env);
     void *mem;
diff --git a/target/arm/tcg/mte_helper.c b/target/arm/tcg/mte_helper.c
index bb48fe359b8c..08b8e7176a6a 100644
--- a/target/arm/tcg/mte_helper.c
+++ b/target/arm/tcg/mte_helper.c
@@ -545,7 +545,7 @@ void HELPER(stzgm_tags)(CPUARMState *env, uint64_t ptr, uint64_t val)
      * i.e. 32 bytes, which is an unreasonably small dcz anyway,
      * to make sure that we can access one complete tag byte here.
      */
-    log2_dcz_bytes = env_archcpu(env)->dcz_blocksize + 2;
+    log2_dcz_bytes = get_dczid_bs(env_archcpu(env)) + 2;
     log2_tag_bytes = log2_dcz_bytes - (LOG2_TAG_GRANULE + 1);
     dcz_bytes = (intptr_t)1 << log2_dcz_bytes;
     tag_bytes = (intptr_t)1 << log2_tag_bytes;
@@ -945,7 +945,7 @@ uint64_t HELPER(mte_check_zva)(CPUARMState *env, uint32_t desc, uint64_t ptr)
      * i.e. 32 bytes, which is an unreasonably small dcz anyway, to make
      * sure that we can access one complete tag byte here.
      */
-    log2_dcz_bytes = env_archcpu(env)->dcz_blocksize + 2;
+    log2_dcz_bytes = get_dczid_bs(env_archcpu(env)) + 2;
     log2_tag_bytes = log2_dcz_bytes - (LOG2_TAG_GRANULE + 1);
     dcz_bytes = (intptr_t)1 << log2_dcz_bytes;
     tag_bytes = (intptr_t)1 << log2_tag_bytes;
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index cde22a5cca73..7a8cd99e004d 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -10712,7 +10712,7 @@ static void aarch64_tr_init_disas_context(DisasContextBase *dcbase,
     dc->vec_stride = 0;
     dc->cp_regs = arm_cpu->cp_regs;
     dc->features = env->features;
-    dc->dcz_blocksize = arm_cpu->dcz_blocksize;
+    dc->dcz_blocksize = get_dczid_bs(arm_cpu);
     dc->gm_blocksize = arm_cpu->gm_blocksize;
 
 #ifdef CONFIG_USER_ONLY
-- 
2.52.0

[PATCH v3 2/2] arm: add DCZID_EL0 to idregs array

[Cornelia Huck]

Continue moving ID registers to the idregs array, so that we
eventually can switch to an autogenerated cpu-sysregs.h.inc.

This requires a bit of care, since we still have to handle the EL
specific part (DCZID_EL0.DZP). The value previously saved in
cpu->dcz_blocksize is now kept in DCZID_EL.BS (transparent to
callers using the wrappers.)

KVM currently does not support DCZID_EL0 via ONE_REG, assert that
we're not trying to do anything with it until it does.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---
 target/arm/cpu-sysregs.h.inc | 1 +
 target/arm/cpu.h             | 8 ++++----
 target/arm/helper.c          | 4 +++-
 target/arm/tcg/translate.h   | 2 +-
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/target/arm/cpu-sysregs.h.inc b/target/arm/cpu-sysregs.h.inc
index 2bb2861c6234..7f3aa8b991aa 100644
--- a/target/arm/cpu-sysregs.h.inc
+++ b/target/arm/cpu-sysregs.h.inc
@@ -39,3 +39,4 @@ DEF(ID_MMFR5_EL1, 3, 0, 0, 3, 6)
 DEF(CLIDR_EL1, 3, 1, 0, 0, 1)
 DEF(ID_AA64ZFR0_EL1, 3, 0, 0, 4, 4)
 DEF(CTR_EL0, 3, 3, 0, 0, 1)
+DEF(DCZID_EL0, 3, 3, 0, 0, 7)
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index c0dae1a891a7..08b7d3fb936a 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1111,8 +1111,6 @@ struct ArchCPU {
     bool prop_pauth_qarma5;
     bool prop_lpa2;
 
-    /* DCZ blocksize, in log_2(words), ie low 4 bits of DCZID_EL0 */
-    uint8_t dcz_blocksize;
     /* GM blocksize, in log_2(words), ie low 4 bits of GMID_EL0 */
     uint8_t gm_blocksize;
 
@@ -1180,12 +1178,14 @@ struct ARMCPUClass {
 
 static inline uint8_t get_dczid_bs(ARMCPU *cpu)
 {
-    return cpu->dcz_blocksize;
+    return extract64(cpu->isar.idregs[DCZID_EL0_IDX], 0, 4);
 }
 
 static inline void set_dczid_bs(ARMCPU *cpu, uint8_t bs)
 {
-    cpu->dcz_blocksize = bs;
+    /* keep dzp unchanged */
+    cpu->isar.idregs[DCZID_EL0_IDX] =
+        deposit64(cpu->isar.idregs[DCZID_EL0_IDX], 0, 4, bs);
 }
 
 /* Callback functions for the generic timer's timers. */
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 61b3b90b63c0..2bcb01e45bbf 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -3320,12 +3320,14 @@ static uint64_t aa64_dczid_read(CPUARMState *env, const ARMCPRegInfo *ri)
     ARMCPU *cpu = env_archcpu(env);
     int dzp_bit = 1 << 4;
 
+    assert(!kvm_enabled());
+
     /* DZP indicates whether DC ZVA access is allowed */
     if (aa64_zva_access(env, NULL, false) == CP_ACCESS_OK) {
         dzp_bit = 0;
     }
 
-    return cpu->dcz_blocksize | dzp_bit;
+    return cpu->isar.idregs[DCZID_EL0_IDX] | dzp_bit;
 }
 
 static CPAccessResult sp_el0_access(CPUARMState *env, const ARMCPRegInfo *ri,
diff --git a/target/arm/tcg/translate.h b/target/arm/tcg/translate.h
index b62104b4ae88..1e30d7c77c37 100644
--- a/target/arm/tcg/translate.h
+++ b/target/arm/tcg/translate.h
@@ -193,7 +193,7 @@ typedef struct DisasContext {
      *  < 0, set by the current instruction.
      */
     int8_t btype;
-    /* A copy of cpu->dcz_blocksize. */
+    /* A copy of DCZID_EL0.BS. */
     uint8_t dcz_blocksize;
     /* A copy of cpu->gm_blocksize. */
     uint8_t gm_blocksize;
-- 
2.52.0

Re: [PATCH v3 1/2] arm: add {get,set}_dczid_bs helpers

[Richard Henderson]

On 1/6/26 02:41, Cornelia Huck wrote:
> Most accesses to cpu->dcz_blocksize really care about
> DCZID_EL0.BS (i.e. the part of the register that does not change at
> different EL.) Wean them off directly dealing with cpu->dcz_blocksize
> so that we can switch to handling DCZID_EL0 differently in a followup
> patch.
> 
> Signed-off-by: Cornelia Huck<cohuck@redhat.com>
> ---
>   target/arm/cpu.c               |  2 +-
>   target/arm/cpu.h               | 10 ++++++++++
>   target/arm/cpu64.c             |  4 ++--
>   target/arm/helper.c            |  1 +
>   target/arm/tcg/cpu64.c         | 22 +++++++++++-----------
>   target/arm/tcg/helper-a64.c    |  2 +-
>   target/arm/tcg/mte_helper.c    |  4 ++--
>   target/arm/tcg/translate-a64.c |  2 +-
>   8 files changed, 29 insertions(+), 18 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

Re: [PATCH v3 1/2] arm: add {get,set}_dczid_bs helpers

[Sebastian Ott]

On Mon, 5 Jan 2026, Cornelia Huck wrote:
> Most accesses to cpu->dcz_blocksize really care about
> DCZID_EL0.BS (i.e. the part of the register that does not change at
> different EL.) Wean them off directly dealing with cpu->dcz_blocksize
> so that we can switch to handling DCZID_EL0 differently in a followup
> patch.
>
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>

Reviewed-by: Sebastian Ott <sebott@redhat.com>

Re: [PATCH v3 2/2] arm: add DCZID_EL0 to idregs array

[Sebastian Ott]

On Mon, 5 Jan 2026, Cornelia Huck wrote:
> Continue moving ID registers to the idregs array, so that we
> eventually can switch to an autogenerated cpu-sysregs.h.inc.
>
> This requires a bit of care, since we still have to handle the EL
> specific part (DCZID_EL0.DZP). The value previously saved in
> cpu->dcz_blocksize is now kept in DCZID_EL.BS (transparent to
> callers using the wrappers.)
>
> KVM currently does not support DCZID_EL0 via ONE_REG, assert that
> we're not trying to do anything with it until it does.
>
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>

Reviewed-by: Sebastian Ott <sebott@redhat.com>

Re: [PATCH v3 0/2] arm: move DCZID_EL0 to idregs array

[Cornelia Huck]

On Mon, Jan 05 2026, Cornelia Huck <cohuck@redhat.com> wrote:

> This is part of the ongoing effort to move all id registers to the idregs
> array (so that we can work with an autogenerated list of registers.)
>
> Changes v2->v3:
> - separate patch for adding the helpers
> - put some rationale into the patch description
>
> Cornelia Huck (2):
>   arm: add {get,set}_dczid_bs helpers
>   arm: add DCZID_EL0 to idregs array
>
>  target/arm/cpu-sysregs.h.inc   |  1 +
>  target/arm/cpu.c               |  2 +-
>  target/arm/cpu.h               | 14 ++++++++++++--
>  target/arm/cpu64.c             |  4 ++--
>  target/arm/helper.c            |  5 ++++-
>  target/arm/tcg/cpu64.c         | 22 +++++++++++-----------
>  target/arm/tcg/helper-a64.c    |  2 +-
>  target/arm/tcg/mte_helper.c    |  4 ++--
>  target/arm/tcg/translate-a64.c |  2 +-
>  target/arm/tcg/translate.h     |  2 +-
>  10 files changed, 36 insertions(+), 22 deletions(-)
>

Friendly ping. Is this one good to go?

Re: [PATCH v3 0/2] arm: move DCZID_EL0 to idregs array

[Peter Maydell]

On Thu, 29 Jan 2026 at 06:54, Cornelia Huck <cohuck@redhat.com> wrote:
>
> On Mon, Jan 05 2026, Cornelia Huck <cohuck@redhat.com> wrote:
>
> > This is part of the ongoing effort to move all id registers to the idregs
> > array (so that we can work with an autogenerated list of registers.)
> >
> > Changes v2->v3:
> > - separate patch for adding the helpers
> > - put some rationale into the patch description
> >
> > Cornelia Huck (2):
> >   arm: add {get,set}_dczid_bs helpers
> >   arm: add DCZID_EL0 to idregs array



Applied to target-arm.next, thanks.

-- PMM