[PATCH v2 0/3] target/riscv/kvm: reset time changes

[PATCH v2 0/3] target/riscv/kvm: reset time changes

[Daniel Henrique Barboza]

Hi,

In this version the following changes were made, based on feedback from
Drew in v1:

- patch 2: reworked. Instead of using a different existing 'env' field
  to get/put the 'sie' CSR, we're adding a new helper that contains all
  reset vals for the KVM CSRs we support
- patch 3: reworked. Add two KVM CSRs from the KVM UAPI that we're not
  using.

Link to v1: https://lore.kernel.org/qemu-riscv/20250220161313.127376-1-dbarboza@ventanamicro.com/ 

Patches based on alistair/riscv-to-apply.next. 

Daniel Henrique Barboza (3):
  target/riscv/cpu: ignore TCG init for KVM CPUs in reset_hold
  target/riscv/kvm: add kvm_riscv_reset_regs_csr()
  target/riscv/kvm: add missing KVM CSRs

 target/riscv/cpu.c         |  9 +++++----
 target/riscv/kvm/kvm-cpu.c | 32 +++++++++++++++++++++-----------
 2 files changed, 26 insertions(+), 15 deletions(-)

-- 
2.48.1

[PATCH v2 1/3] target/riscv/cpu: ignore TCG init for KVM CPUs in reset_hold

[Daniel Henrique Barboza]

riscv_cpu_reset_hold() does a lot of TCG-related initializations that
aren't relevant for KVM, but nevertheless are impacting the reset state
of KVM vcpus.

When running a KVM guest, kvm_riscv_reset_vcpu() is called at the end of
reset_hold(). At that point env->mstatus is initialized to a non-zero
value, and it will be use to write 'sstatus' in the vcpu
(kvm_arch_put_registers() then kvm_riscv_put_regs_csr()).

Do an early exit in riscv_cpu_reset_hold() if we're running KVM. All the
KVM reset procedure will be centered in kvm_riscv_reset_vcpu().

While we're at it, remove the kvm_enabled() check in
kvm_riscv_reset_vcpu() since it's already being gated in
riscv_cpu_reset_hold().

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 target/riscv/cpu.c         | 9 +++++----
 target/riscv/kvm/kvm-cpu.c | 3 ---
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 522d6584e4..8e6e629ec4 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -1050,6 +1050,11 @@ static void riscv_cpu_reset_hold(Object *obj, ResetType type)
         mcc->parent_phases.hold(obj, type);
     }
 #ifndef CONFIG_USER_ONLY
+    if (kvm_enabled()) {
+        kvm_riscv_reset_vcpu(cpu);
+        return;
+    }
+
     env->misa_mxl = mcc->misa_mxl_max;
     env->priv = PRV_M;
     env->mstatus &= ~(MSTATUS_MIE | MSTATUS_MPRV);
@@ -1146,10 +1151,6 @@ static void riscv_cpu_reset_hold(Object *obj, ResetType type)
         env->rnmip = 0;
         env->mnstatus = set_field(env->mnstatus, MNSTATUS_NMIE, false);
     }
-
-    if (kvm_enabled()) {
-        kvm_riscv_reset_vcpu(cpu);
-    }
 #endif
 }
 
diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index 23ce779359..484b6afe7c 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -1603,9 +1603,6 @@ void kvm_riscv_reset_vcpu(RISCVCPU *cpu)
     CPURISCVState *env = &cpu->env;
     int i;
 
-    if (!kvm_enabled()) {
-        return;
-    }
     for (i = 0; i < 32; i++) {
         env->gpr[i] = 0;
     }
-- 
2.48.1

[PATCH v2 2/3] target/riscv/kvm: add kvm_riscv_reset_regs_csr()

[Daniel Henrique Barboza]

We're setting reset vals for KVM csrs during kvm_riscv_reset_vcpu(), but
in no particular order and missing some of them (like env->mstatus).

Create a helper to do that, unclogging reset_vcpu(), and initialize
env->mstatus as well. Keep the regs in the same order they appear in
struct kvm_riscv_csr from the KVM UAPI, similar to what
kvm_riscv_(get|put)_regs_csr are doing. This will make a bit easier to
add new KVM CSRs and to verify which values we're writing back to KVM
during vcpu reset.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/kvm/kvm-cpu.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index 484b6afe7c..f14fcc58bb 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -605,6 +605,19 @@ static int kvm_riscv_put_regs_core(CPUState *cs)
     return ret;
 }
 
+static void kvm_riscv_reset_regs_csr(CPURISCVState *env)
+{
+    env->mstatus = 0;
+    env->mie = 0;
+    env->stvec = 0;
+    env->sscratch = 0;
+    env->sepc = 0;
+    env->scause = 0;
+    env->stval = 0;
+    env->mip = 0;
+    env->satp = 0;
+}
+
 static int kvm_riscv_get_regs_csr(CPUState *cs)
 {
     CPURISCVState *env = &RISCV_CPU(cs)->env;
@@ -1609,14 +1622,8 @@ void kvm_riscv_reset_vcpu(RISCVCPU *cpu)
     env->pc = cpu->env.kernel_addr;
     env->gpr[10] = kvm_arch_vcpu_id(CPU(cpu)); /* a0 */
     env->gpr[11] = cpu->env.fdt_addr;          /* a1 */
-    env->satp = 0;
-    env->mie = 0;
-    env->stvec = 0;
-    env->sscratch = 0;
-    env->sepc = 0;
-    env->scause = 0;
-    env->stval = 0;
-    env->mip = 0;
+
+    kvm_riscv_reset_regs_csr(env);
 }
 
 void kvm_riscv_set_irq(RISCVCPU *cpu, int irq, int level)
-- 
2.48.1

Re: [PATCH v2 2/3] target/riscv/kvm: add kvm_riscv_reset_regs_csr()

[Andrew Jones]

On Fri, Feb 21, 2025 at 09:26:22AM -0300, Daniel Henrique Barboza wrote:
> We're setting reset vals for KVM csrs during kvm_riscv_reset_vcpu(), but
> in no particular order and missing some of them (like env->mstatus).
> 
> Create a helper to do that, unclogging reset_vcpu(), and initialize
> env->mstatus as well. Keep the regs in the same order they appear in
> struct kvm_riscv_csr from the KVM UAPI, similar to what
> kvm_riscv_(get|put)_regs_csr are doing. This will make a bit easier to
> add new KVM CSRs and to verify which values we're writing back to KVM
> during vcpu reset.
> 
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/kvm/kvm-cpu.c | 23 +++++++++++++++--------
>  1 file changed, 15 insertions(+), 8 deletions(-)
> 
> diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> index 484b6afe7c..f14fcc58bb 100644
> --- a/target/riscv/kvm/kvm-cpu.c
> +++ b/target/riscv/kvm/kvm-cpu.c
> @@ -605,6 +605,19 @@ static int kvm_riscv_put_regs_core(CPUState *cs)
>      return ret;
>  }
>  
> +static void kvm_riscv_reset_regs_csr(CPURISCVState *env)
> +{
> +    env->mstatus = 0;
> +    env->mie = 0;
> +    env->stvec = 0;
> +    env->sscratch = 0;
> +    env->sepc = 0;
> +    env->scause = 0;
> +    env->stval = 0;
> +    env->mip = 0;
> +    env->satp = 0;
> +}
> +
>  static int kvm_riscv_get_regs_csr(CPUState *cs)
>  {
>      CPURISCVState *env = &RISCV_CPU(cs)->env;
> @@ -1609,14 +1622,8 @@ void kvm_riscv_reset_vcpu(RISCVCPU *cpu)
>      env->pc = cpu->env.kernel_addr;
>      env->gpr[10] = kvm_arch_vcpu_id(CPU(cpu)); /* a0 */
>      env->gpr[11] = cpu->env.fdt_addr;          /* a1 */
> -    env->satp = 0;
> -    env->mie = 0;
> -    env->stvec = 0;
> -    env->sscratch = 0;
> -    env->sepc = 0;
> -    env->scause = 0;
> -    env->stval = 0;
> -    env->mip = 0;
> +
> +    kvm_riscv_reset_regs_csr(env);
>  }
>  
>  void kvm_riscv_set_irq(RISCVCPU *cpu, int irq, int level)
> -- 
> 2.48.1
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

[PATCH v2 3/3] target/riscv/kvm: add missing KVM CSRs

[Daniel Henrique Barboza]

We're missing scounteren and senvcfg CSRs, both already present in the
KVM UAPI.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/kvm/kvm-cpu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index f14fcc58bb..017ca82226 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -616,6 +616,8 @@ static void kvm_riscv_reset_regs_csr(CPURISCVState *env)
     env->stval = 0;
     env->mip = 0;
     env->satp = 0;
+    env->scounteren = 0;
+    env->senvcfg = 0;
 }
 
 static int kvm_riscv_get_regs_csr(CPUState *cs)
@@ -631,6 +633,8 @@ static int kvm_riscv_get_regs_csr(CPUState *cs)
     KVM_RISCV_GET_CSR(cs, env, stval, env->stval);
     KVM_RISCV_GET_CSR(cs, env, sip, env->mip);
     KVM_RISCV_GET_CSR(cs, env, satp, env->satp);
+    KVM_RISCV_GET_CSR(cs, env, scounteren, env->scounteren);
+    KVM_RISCV_GET_CSR(cs, env, senvcfg, env->senvcfg);
 
     return 0;
 }
@@ -648,6 +652,8 @@ static int kvm_riscv_put_regs_csr(CPUState *cs)
     KVM_RISCV_SET_CSR(cs, env, stval, env->stval);
     KVM_RISCV_SET_CSR(cs, env, sip, env->mip);
     KVM_RISCV_SET_CSR(cs, env, satp, env->satp);
+    KVM_RISCV_SET_CSR(cs, env, scounteren, env->scounteren);
+    KVM_RISCV_SET_CSR(cs, env, senvcfg, env->senvcfg);
 
     return 0;
 }
-- 
2.48.1

Re: [PATCH v2 3/3] target/riscv/kvm: add missing KVM CSRs

[Andrew Jones]

On Fri, Feb 21, 2025 at 09:26:23AM -0300, Daniel Henrique Barboza wrote:
> We're missing scounteren and senvcfg CSRs, both already present in the
> KVM UAPI.
> 
> Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>  target/riscv/kvm/kvm-cpu.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> index f14fcc58bb..017ca82226 100644
> --- a/target/riscv/kvm/kvm-cpu.c
> +++ b/target/riscv/kvm/kvm-cpu.c
> @@ -616,6 +616,8 @@ static void kvm_riscv_reset_regs_csr(CPURISCVState *env)
>      env->stval = 0;
>      env->mip = 0;
>      env->satp = 0;
> +    env->scounteren = 0;
> +    env->senvcfg = 0;
>  }
>  
>  static int kvm_riscv_get_regs_csr(CPUState *cs)
> @@ -631,6 +633,8 @@ static int kvm_riscv_get_regs_csr(CPUState *cs)
>      KVM_RISCV_GET_CSR(cs, env, stval, env->stval);
>      KVM_RISCV_GET_CSR(cs, env, sip, env->mip);
>      KVM_RISCV_GET_CSR(cs, env, satp, env->satp);
> +    KVM_RISCV_GET_CSR(cs, env, scounteren, env->scounteren);
> +    KVM_RISCV_GET_CSR(cs, env, senvcfg, env->senvcfg);
>  
>      return 0;
>  }
> @@ -648,6 +652,8 @@ static int kvm_riscv_put_regs_csr(CPUState *cs)
>      KVM_RISCV_SET_CSR(cs, env, stval, env->stval);
>      KVM_RISCV_SET_CSR(cs, env, sip, env->mip);
>      KVM_RISCV_SET_CSR(cs, env, satp, env->satp);
> +    KVM_RISCV_SET_CSR(cs, env, scounteren, env->scounteren);
> +    KVM_RISCV_SET_CSR(cs, env, senvcfg, env->senvcfg);
>  
>      return 0;
>  }
> -- 
> 2.48.1
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Re: [PATCH v2 0/3] target/riscv/kvm: reset time changes

[Daniel Henrique Barboza]

Hi Alistair,


Can you please take a look in this series? This will collide with another
series that are changing KVM CSRs that will require a rebase. Might
as well do a rebase on top of this set too since it's fully acked already.


Thanks,

Daniel

On 2/21/25 9:26 AM, Daniel Henrique Barboza wrote:
> Hi,
> 
> In this version the following changes were made, based on feedback from
> Drew in v1:
> 
> - patch 2: reworked. Instead of using a different existing 'env' field
>    to get/put the 'sie' CSR, we're adding a new helper that contains all
>    reset vals for the KVM CSRs we support
> - patch 3: reworked. Add two KVM CSRs from the KVM UAPI that we're not
>    using.
> 
> Link to v1: https://lore.kernel.org/qemu-riscv/20250220161313.127376-1-dbarboza@ventanamicro.com/
> 
> Patches based on alistair/riscv-to-apply.next.
> 
> Daniel Henrique Barboza (3):
>    target/riscv/cpu: ignore TCG init for KVM CPUs in reset_hold
>    target/riscv/kvm: add kvm_riscv_reset_regs_csr()
>    target/riscv/kvm: add missing KVM CSRs
> 
>   target/riscv/cpu.c         |  9 +++++----
>   target/riscv/kvm/kvm-cpu.c | 32 +++++++++++++++++++++-----------
>   2 files changed, 26 insertions(+), 15 deletions(-)
>