[PATCH v2 0/6] riscv: zicntr/zihpm flags and disable support

[PATCH v2 0/6] riscv: zicntr/zihpm flags and disable support

[Daniel Henrique Barboza]

Hi,

This is a follow-up of the work done in [1] after review comments made
in the rva22u64 profile support review [2].

zicntr and zihpm are already implemented by QEMU before they were added
as discrete extensions by RVI. This puts QEMU in a weird spot because it
has enabled default extensions that aren't togglable on/off via user
flags and aren't reported in riscv,isa as present.

There's no reason to no treat both zicntr and zihpm as regular
extensions, reporting their existence in riscv,isa DT and allowing users
to disable them. This will also benefit us in the incoming profile
support, since disabling a profile should disable all its mandatory
extensions, and for the rva22u64 profile this means that both zicntr and
zihpm should be disabled as well. 

Let's add user flags and disable support for both in all accelerators
(TCG and KVM). FWIW Linux boot doesn't seem to care about the lack of
both zicntr and zihpm when running TCG, although attempting to use the
timers will result in SIGILL.


[1] https://lore.kernel.org/qemu-riscv/20230717215419.124258-1-dbarboza@ventanamicro.com/
[2] https://lore.kernel.org/qemu-riscv/20231017-e7a4712137165b59844499e3@orel/T/#m3bb0e3c9b00d9edd168da9f7de0bc26df4f7d6ab

Daniel Henrique Barboza (6):
  target/riscv/cpu.c: add zicntr extension flag
  target/riscv/tcg: add ext_zicntr disable support
  target/riscv/kvm: add zicntr reg
  target/riscv/cpu.c: add zihpm extension flag
  target/riscv/tcg: add ext_zihpm disable support
  target/riscv/kvm: add zihpm reg

 target/riscv/cpu.c         | 15 +++++++++++++++
 target/riscv/cpu_cfg.h     |  2 ++
 target/riscv/csr.c         |  4 ++++
 target/riscv/kvm/kvm-cpu.c |  2 ++
 target/riscv/tcg/tcg-cpu.c | 21 +++++++++++++++++++++
 5 files changed, 44 insertions(+)

-- 
2.41.0

[PATCH v2 1/6] target/riscv/cpu.c: add zicntr extension flag

[Daniel Henrique Barboza]

zicntr is the Base Counters and Timers extension described in chapter 12
of the unprivileged spec. It describes support for RDCYCLE, RDTIME and
RDINSTRET.

QEMU already implements it way before it was a discrete extension.
zicntr is part of the RVA22 profile, so let's add it to QEMU to make the
future profile implementation flag complete.

Given than it represents an already existing feature, default it to
'true' for all CPUs. Accelerators are responsible for disabling them if
the user wants to.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/cpu.c     | 12 ++++++++++++
 target/riscv/cpu_cfg.h |  1 +
 2 files changed, 13 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 2f98ce56e0..f478245254 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -79,6 +79,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
     ISA_EXT_DATA_ENTRY(zicbom, PRIV_VERSION_1_12_0, ext_zicbom),
     ISA_EXT_DATA_ENTRY(zicboz, PRIV_VERSION_1_12_0, ext_zicboz),
     ISA_EXT_DATA_ENTRY(zicond, PRIV_VERSION_1_12_0, ext_zicond),
+    ISA_EXT_DATA_ENTRY(zicntr, PRIV_VERSION_1_12_0, ext_zicntr),
     ISA_EXT_DATA_ENTRY(zicsr, PRIV_VERSION_1_10_0, ext_zicsr),
     ISA_EXT_DATA_ENTRY(zifencei, PRIV_VERSION_1_10_0, ext_zifencei),
     ISA_EXT_DATA_ENTRY(zihintntl, PRIV_VERSION_1_10_0, ext_zihintntl),
@@ -1175,6 +1176,15 @@ static void riscv_cpu_init(Object *obj)
     qdev_init_gpio_in(DEVICE(obj), riscv_cpu_set_irq,
                       IRQ_LOCAL_MAX + IRQ_LOCAL_GUEST_MAX);
 #endif /* CONFIG_USER_ONLY */
+
+    /*
+     * The timer and performance counters extensions were supported
+     * in QEMU before they were added as discrete extensions in the
+     * ISA. To keep compatibility we'll always default them to 'true'
+     * for all CPUs. Each accelerator will decide what to do when
+     * users disable them.
+     */
+    RISCV_CPU(obj)->cfg.ext_zicntr = true;
 }
 
 typedef struct misa_ext_info {
@@ -1263,6 +1273,8 @@ const RISCVCPUMultiExtConfig riscv_cpu_extensions[] = {
     MULTI_EXT_CFG_BOOL("svnapot", ext_svnapot, false),
     MULTI_EXT_CFG_BOOL("svpbmt", ext_svpbmt, false),
 
+    MULTI_EXT_CFG_BOOL("zicntr", ext_zicntr, true),
+
     MULTI_EXT_CFG_BOOL("zba", ext_zba, true),
     MULTI_EXT_CFG_BOOL("zbb", ext_zbb, true),
     MULTI_EXT_CFG_BOOL("zbc", ext_zbc, true),
diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
index 208cac1c7c..3c91b63609 100644
--- a/target/riscv/cpu_cfg.h
+++ b/target/riscv/cpu_cfg.h
@@ -62,6 +62,7 @@ struct RISCVCPUConfig {
     bool ext_zksh;
     bool ext_zkt;
     bool ext_zifencei;
+    bool ext_zicntr;
     bool ext_zicsr;
     bool ext_zicbom;
     bool ext_zicboz;
-- 
2.41.0

[PATCH v2 2/6] target/riscv/tcg: add ext_zicntr disable support

[Daniel Henrique Barboza]

Support for the zicntr counters are already in place. We need a way to
disable them if the user wants to. This is done by restricting access to
the CYCLE, TIME, and INSTRET counters via the 'ctr()' predicate when
we're about to access them.

Disabling zicntr happens via the command line or if its dependency,
zicsr, happens to be disabled. We'll check for zicsr during realize() and,
in case it's absent, disable zicntr. However, if the user was explicit
about having zicntr support, error out instead of disabling it.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/csr.c         | 4 ++++
 target/riscv/tcg/tcg-cpu.c | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index a5be1c202c..05c6a69123 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -122,6 +122,10 @@ static RISCVException ctr(CPURISCVState *env, int csrno)
 
     if ((csrno >= CSR_CYCLE && csrno <= CSR_INSTRET) ||
         (csrno >= CSR_CYCLEH && csrno <= CSR_INSTRETH)) {
+        if (!riscv_cpu_cfg(env)->ext_zicntr) {
+            return RISCV_EXCP_ILLEGAL_INST;
+        }
+
         goto skip_ext_pmu_check;
     }
 
diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index bbce254ee1..a01b876621 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -541,6 +541,14 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
         cpu_cfg_ext_auto_update(cpu, CPU_CFG_OFFSET(ext_zksh), true);
     }
 
+    if (cpu->cfg.ext_zicntr && !cpu->cfg.ext_zicsr) {
+        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_zicntr))) {
+            error_setg(errp, "zicntr requires zicsr");
+            return;
+        }
+        cpu->cfg.ext_zicntr = false;
+    }
+
     /*
      * Disable isa extensions based on priv spec after we
      * validated and set everything we need.
-- 
2.41.0

[PATCH v2 3/6] target/riscv/kvm: add zicntr reg

[Daniel Henrique Barboza]

Add zicntr support in the KVM driver now that QEMU supports it.

This reg was added in Linux 6.6.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/kvm/kvm-cpu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index 5695f2face..6c2a92d171 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -215,6 +215,7 @@ static void kvm_riscv_update_cpu_misa_ext(RISCVCPU *cpu, CPUState *cs)
 static KVMCPUConfig kvm_multi_ext_cfgs[] = {
     KVM_EXT_CFG("zicbom", ext_zicbom, KVM_RISCV_ISA_EXT_ZICBOM),
     KVM_EXT_CFG("zicboz", ext_zicboz, KVM_RISCV_ISA_EXT_ZICBOZ),
+    KVM_EXT_CFG("zicntr", ext_zicntr, KVM_RISCV_ISA_EXT_ZICNTR),
     KVM_EXT_CFG("zihintpause", ext_zihintpause, KVM_RISCV_ISA_EXT_ZIHINTPAUSE),
     KVM_EXT_CFG("zbb", ext_zbb, KVM_RISCV_ISA_EXT_ZBB),
     KVM_EXT_CFG("ssaia", ext_ssaia, KVM_RISCV_ISA_EXT_SSAIA),
-- 
2.41.0

[PATCH v2 4/6] target/riscv/cpu.c: add zihpm extension flag

[Daniel Henrique Barboza]

zihpm is the Hardware Performance Counters extension described in
chapter 12 of the unprivileged spec. It describes support for 29
unprivileged performance counters, hpmcounter3-hpmcounter31.

As with zicntr, QEMU already implements zihpm before it was even an
extension. zihpm is also part of the RVA22 profile, so add it to QEMU
to complement the future profile implementation.

Default it to 'true' for all existing CPUs since it was always present
in the code.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/cpu.c     | 3 +++
 target/riscv/cpu_cfg.h | 1 +
 2 files changed, 4 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index f478245254..c64cd726f4 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -84,6 +84,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
     ISA_EXT_DATA_ENTRY(zifencei, PRIV_VERSION_1_10_0, ext_zifencei),
     ISA_EXT_DATA_ENTRY(zihintntl, PRIV_VERSION_1_10_0, ext_zihintntl),
     ISA_EXT_DATA_ENTRY(zihintpause, PRIV_VERSION_1_10_0, ext_zihintpause),
+    ISA_EXT_DATA_ENTRY(zihpm, PRIV_VERSION_1_12_0, ext_zihpm),
     ISA_EXT_DATA_ENTRY(zmmul, PRIV_VERSION_1_12_0, ext_zmmul),
     ISA_EXT_DATA_ENTRY(zawrs, PRIV_VERSION_1_12_0, ext_zawrs),
     ISA_EXT_DATA_ENTRY(zfa, PRIV_VERSION_1_12_0, ext_zfa),
@@ -1185,6 +1186,7 @@ static void riscv_cpu_init(Object *obj)
      * users disable them.
      */
     RISCV_CPU(obj)->cfg.ext_zicntr = true;
+    RISCV_CPU(obj)->cfg.ext_zihpm = true;
 }
 
 typedef struct misa_ext_info {
@@ -1274,6 +1276,7 @@ const RISCVCPUMultiExtConfig riscv_cpu_extensions[] = {
     MULTI_EXT_CFG_BOOL("svpbmt", ext_svpbmt, false),
 
     MULTI_EXT_CFG_BOOL("zicntr", ext_zicntr, true),
+    MULTI_EXT_CFG_BOOL("zihpm", ext_zihpm, true),
 
     MULTI_EXT_CFG_BOOL("zba", ext_zba, true),
     MULTI_EXT_CFG_BOOL("zbb", ext_zbb, true),
diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
index 3c91b63609..173bd7d910 100644
--- a/target/riscv/cpu_cfg.h
+++ b/target/riscv/cpu_cfg.h
@@ -69,6 +69,7 @@ struct RISCVCPUConfig {
     bool ext_zicond;
     bool ext_zihintntl;
     bool ext_zihintpause;
+    bool ext_zihpm;
     bool ext_smstateen;
     bool ext_sstc;
     bool ext_svadu;
-- 
2.41.0

[PATCH v2 5/6] target/riscv/tcg: add ext_zihpm disable support

[Daniel Henrique Barboza]

Disabling ext_zihpm does nothing at this moment. Add support to disable
the hpmcounter3-hpmcounter31 counters if the user disables zihpm.

There is already code in place in target/riscv/csr.c in all predicates
for these counters (ctr() and mctr()) that disables them if
cpu->cfg.pmu_num is zero. Thus, setting cpu->cfg.pmu_num to zero if
'zihpm=false' is enough to disable the extension.

Set cpu->pmu_avail_ctrs mask to zero as well since this is also checked
to verify if the counters exist.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/tcg/tcg-cpu.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index a01b876621..7a4400e2ba 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -549,6 +549,19 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
         cpu->cfg.ext_zicntr = false;
     }
 
+    if (cpu->cfg.ext_zihpm && !cpu->cfg.ext_zicsr) {
+        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_zihpm))) {
+            error_setg(errp, "zihpm requires zicsr");
+            return;
+        }
+        cpu->cfg.ext_zihpm = false;
+    }
+
+    if (!cpu->cfg.ext_zihpm) {
+        cpu->cfg.pmu_num = 0;
+        cpu->pmu_avail_ctrs = 0;
+    }
+
     /*
      * Disable isa extensions based on priv spec after we
      * validated and set everything we need.
-- 
2.41.0

[PATCH v2 6/6] target/riscv/kvm: add zihpm reg

[Daniel Henrique Barboza]

Add zihpm support in the KVM driver now that QEMU supports it.

This reg was added in Linux 6.6.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/kvm/kvm-cpu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index 6c2a92d171..5246fc2bdc 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -217,6 +217,7 @@ static KVMCPUConfig kvm_multi_ext_cfgs[] = {
     KVM_EXT_CFG("zicboz", ext_zicboz, KVM_RISCV_ISA_EXT_ZICBOZ),
     KVM_EXT_CFG("zicntr", ext_zicntr, KVM_RISCV_ISA_EXT_ZICNTR),
     KVM_EXT_CFG("zihintpause", ext_zihintpause, KVM_RISCV_ISA_EXT_ZIHINTPAUSE),
+    KVM_EXT_CFG("zihpm", ext_zihpm, KVM_RISCV_ISA_EXT_ZIHPM),
     KVM_EXT_CFG("zbb", ext_zbb, KVM_RISCV_ISA_EXT_ZBB),
     KVM_EXT_CFG("ssaia", ext_ssaia, KVM_RISCV_ISA_EXT_SSAIA),
     KVM_EXT_CFG("sstc", ext_sstc, KVM_RISCV_ISA_EXT_SSTC),
-- 
2.41.0

Re: [PATCH v2 2/6] target/riscv/tcg: add ext_zicntr disable support

[Alistair Francis]

On Wed, Oct 18, 2023 at 8:13 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> Support for the zicntr counters are already in place. We need a way to
> disable them if the user wants to. This is done by restricting access to
> the CYCLE, TIME, and INSTRET counters via the 'ctr()' predicate when
> we're about to access them.
>
> Disabling zicntr happens via the command line or if its dependency,
> zicsr, happens to be disabled. We'll check for zicsr during realize() and,
> in case it's absent, disable zicntr. However, if the user was explicit
> about having zicntr support, error out instead of disabling it.
>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

This should come before we expose the property to users though

Alistair

> ---
>  target/riscv/csr.c         | 4 ++++
>  target/riscv/tcg/tcg-cpu.c | 8 ++++++++
>  2 files changed, 12 insertions(+)
>
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index a5be1c202c..05c6a69123 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
> @@ -122,6 +122,10 @@ static RISCVException ctr(CPURISCVState *env, int csrno)
>
>      if ((csrno >= CSR_CYCLE && csrno <= CSR_INSTRET) ||
>          (csrno >= CSR_CYCLEH && csrno <= CSR_INSTRETH)) {
> +        if (!riscv_cpu_cfg(env)->ext_zicntr) {
> +            return RISCV_EXCP_ILLEGAL_INST;
> +        }
> +
>          goto skip_ext_pmu_check;
>      }
>
> diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
> index bbce254ee1..a01b876621 100644
> --- a/target/riscv/tcg/tcg-cpu.c
> +++ b/target/riscv/tcg/tcg-cpu.c
> @@ -541,6 +541,14 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
>          cpu_cfg_ext_auto_update(cpu, CPU_CFG_OFFSET(ext_zksh), true);
>      }
>
> +    if (cpu->cfg.ext_zicntr && !cpu->cfg.ext_zicsr) {
> +        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_zicntr))) {
> +            error_setg(errp, "zicntr requires zicsr");
> +            return;
> +        }
> +        cpu->cfg.ext_zicntr = false;
> +    }
> +
>      /*
>       * Disable isa extensions based on priv spec after we
>       * validated and set everything we need.
> --
> 2.41.0
>
>

Re: [PATCH v2 3/6] target/riscv/kvm: add zicntr reg

[Alistair Francis]

On Wed, Oct 18, 2023 at 8:13 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> Add zicntr support in the KVM driver now that QEMU supports it.
>
> This reg was added in Linux 6.6.
>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/kvm/kvm-cpu.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> index 5695f2face..6c2a92d171 100644
> --- a/target/riscv/kvm/kvm-cpu.c
> +++ b/target/riscv/kvm/kvm-cpu.c
> @@ -215,6 +215,7 @@ static void kvm_riscv_update_cpu_misa_ext(RISCVCPU *cpu, CPUState *cs)
>  static KVMCPUConfig kvm_multi_ext_cfgs[] = {
>      KVM_EXT_CFG("zicbom", ext_zicbom, KVM_RISCV_ISA_EXT_ZICBOM),
>      KVM_EXT_CFG("zicboz", ext_zicboz, KVM_RISCV_ISA_EXT_ZICBOZ),
> +    KVM_EXT_CFG("zicntr", ext_zicntr, KVM_RISCV_ISA_EXT_ZICNTR),
>      KVM_EXT_CFG("zihintpause", ext_zihintpause, KVM_RISCV_ISA_EXT_ZIHINTPAUSE),
>      KVM_EXT_CFG("zbb", ext_zbb, KVM_RISCV_ISA_EXT_ZBB),
>      KVM_EXT_CFG("ssaia", ext_ssaia, KVM_RISCV_ISA_EXT_SSAIA),
> --
> 2.41.0
>
>

Re: [PATCH v2 4/6] target/riscv/cpu.c: add zihpm extension flag

[Alistair Francis]

On Wed, Oct 18, 2023 at 8:14 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> zihpm is the Hardware Performance Counters extension described in
> chapter 12 of the unprivileged spec. It describes support for 29
> unprivileged performance counters, hpmcounter3-hpmcounter31.
>
> As with zicntr, QEMU already implements zihpm before it was even an
> extension. zihpm is also part of the RVA22 profile, so add it to QEMU
> to complement the future profile implementation.
>
> Default it to 'true' for all existing CPUs since it was always present
> in the code.
>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/cpu.c     | 3 +++
>  target/riscv/cpu_cfg.h | 1 +
>  2 files changed, 4 insertions(+)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index f478245254..c64cd726f4 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -84,6 +84,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(zifencei, PRIV_VERSION_1_10_0, ext_zifencei),
>      ISA_EXT_DATA_ENTRY(zihintntl, PRIV_VERSION_1_10_0, ext_zihintntl),
>      ISA_EXT_DATA_ENTRY(zihintpause, PRIV_VERSION_1_10_0, ext_zihintpause),
> +    ISA_EXT_DATA_ENTRY(zihpm, PRIV_VERSION_1_12_0, ext_zihpm),
>      ISA_EXT_DATA_ENTRY(zmmul, PRIV_VERSION_1_12_0, ext_zmmul),
>      ISA_EXT_DATA_ENTRY(zawrs, PRIV_VERSION_1_12_0, ext_zawrs),
>      ISA_EXT_DATA_ENTRY(zfa, PRIV_VERSION_1_12_0, ext_zfa),
> @@ -1185,6 +1186,7 @@ static void riscv_cpu_init(Object *obj)
>       * users disable them.
>       */
>      RISCV_CPU(obj)->cfg.ext_zicntr = true;
> +    RISCV_CPU(obj)->cfg.ext_zihpm = true;
>  }
>
>  typedef struct misa_ext_info {
> @@ -1274,6 +1276,7 @@ const RISCVCPUMultiExtConfig riscv_cpu_extensions[] = {
>      MULTI_EXT_CFG_BOOL("svpbmt", ext_svpbmt, false),
>
>      MULTI_EXT_CFG_BOOL("zicntr", ext_zicntr, true),
> +    MULTI_EXT_CFG_BOOL("zihpm", ext_zihpm, true),

Same here. Just make this change after or with the logic to disable
the extension

Alistair

>
>      MULTI_EXT_CFG_BOOL("zba", ext_zba, true),
>      MULTI_EXT_CFG_BOOL("zbb", ext_zbb, true),
> diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
> index 3c91b63609..173bd7d910 100644
> --- a/target/riscv/cpu_cfg.h
> +++ b/target/riscv/cpu_cfg.h
> @@ -69,6 +69,7 @@ struct RISCVCPUConfig {
>      bool ext_zicond;
>      bool ext_zihintntl;
>      bool ext_zihintpause;
> +    bool ext_zihpm;
>      bool ext_smstateen;
>      bool ext_sstc;
>      bool ext_svadu;
> --
> 2.41.0
>
>

Re: [PATCH v2 6/6] target/riscv/kvm: add zihpm reg

[Alistair Francis]

On Wed, Oct 18, 2023 at 8:14 AM Daniel Henrique Barboza
<dbarboza@ventanamicro.com> wrote:
>
> Add zihpm support in the KVM driver now that QEMU supports it.
>
> This reg was added in Linux 6.6.
>
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/kvm/kvm-cpu.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> index 6c2a92d171..5246fc2bdc 100644
> --- a/target/riscv/kvm/kvm-cpu.c
> +++ b/target/riscv/kvm/kvm-cpu.c
> @@ -217,6 +217,7 @@ static KVMCPUConfig kvm_multi_ext_cfgs[] = {
>      KVM_EXT_CFG("zicboz", ext_zicboz, KVM_RISCV_ISA_EXT_ZICBOZ),
>      KVM_EXT_CFG("zicntr", ext_zicntr, KVM_RISCV_ISA_EXT_ZICNTR),
>      KVM_EXT_CFG("zihintpause", ext_zihintpause, KVM_RISCV_ISA_EXT_ZIHINTPAUSE),
> +    KVM_EXT_CFG("zihpm", ext_zihpm, KVM_RISCV_ISA_EXT_ZIHPM),
>      KVM_EXT_CFG("zbb", ext_zbb, KVM_RISCV_ISA_EXT_ZBB),
>      KVM_EXT_CFG("ssaia", ext_ssaia, KVM_RISCV_ISA_EXT_SSAIA),
>      KVM_EXT_CFG("sstc", ext_sstc, KVM_RISCV_ISA_EXT_SSTC),
> --
> 2.41.0
>
>

Re: [PATCH v2 2/6] target/riscv/tcg: add ext_zicntr disable support

[Daniel Henrique Barboza]

On 10/22/23 23:54, Alistair Francis wrote:
> On Wed, Oct 18, 2023 at 8:13 AM Daniel Henrique Barboza
> <dbarboza@ventanamicro.com> wrote:
>>
>> Support for the zicntr counters are already in place. We need a way to
>> disable them if the user wants to. This is done by restricting access to
>> the CYCLE, TIME, and INSTRET counters via the 'ctr()' predicate when
>> we're about to access them.
>>
>> Disabling zicntr happens via the command line or if its dependency,
>> zicsr, happens to be disabled. We'll check for zicsr during realize() and,
>> in case it's absent, disable zicntr. However, if the user was explicit
>> about having zicntr support, error out instead of disabling it.
>>
>> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> 
> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> 
> This should come before we expose the property to users though

I'll merge this patch with patch 1. Same thing with patch 4 and 5.


Thanks,

Daniel

> 
> Alistair
> 
>> ---
>>   target/riscv/csr.c         | 4 ++++
>>   target/riscv/tcg/tcg-cpu.c | 8 ++++++++
>>   2 files changed, 12 insertions(+)
>>
>> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
>> index a5be1c202c..05c6a69123 100644
>> --- a/target/riscv/csr.c
>> +++ b/target/riscv/csr.c
>> @@ -122,6 +122,10 @@ static RISCVException ctr(CPURISCVState *env, int csrno)
>>
>>       if ((csrno >= CSR_CYCLE && csrno <= CSR_INSTRET) ||
>>           (csrno >= CSR_CYCLEH && csrno <= CSR_INSTRETH)) {
>> +        if (!riscv_cpu_cfg(env)->ext_zicntr) {
>> +            return RISCV_EXCP_ILLEGAL_INST;
>> +        }
>> +
>>           goto skip_ext_pmu_check;
>>       }
>>
>> diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
>> index bbce254ee1..a01b876621 100644
>> --- a/target/riscv/tcg/tcg-cpu.c
>> +++ b/target/riscv/tcg/tcg-cpu.c
>> @@ -541,6 +541,14 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
>>           cpu_cfg_ext_auto_update(cpu, CPU_CFG_OFFSET(ext_zksh), true);
>>       }
>>
>> +    if (cpu->cfg.ext_zicntr && !cpu->cfg.ext_zicsr) {
>> +        if (cpu_cfg_ext_is_user_set(CPU_CFG_OFFSET(ext_zicntr))) {
>> +            error_setg(errp, "zicntr requires zicsr");
>> +            return;
>> +        }
>> +        cpu->cfg.ext_zicntr = false;
>> +    }
>> +
>>       /*
>>        * Disable isa extensions based on priv spec after we
>>        * validated and set everything we need.
>> --
>> 2.41.0
>>
>>