Re: [PATCH v4 10/12] target/riscv: Add kvm_riscv_get/put_regs_timer

[Alistair Francis <alistair23@xxxxxxxxx>]

On Mon, Jan 10, 2022 at 11:54 AM Yifei Jiang via <qemu-devel@xxxxxxxxxx> wrote:
>
> Add kvm_riscv_get/put_regs_timer to synchronize virtual time context
> from KVM.
>
> To set register of RISCV_TIMER_REG(state) will occur a error from KVM
> on kvm_timer_state == 0. It's better to adapt in KVM, but it doesn't matter
> that adaping in QEMU.
>
> Signed-off-by: Yifei Jiang <jiangyifei@xxxxxxxxxx>
> Signed-off-by: Mingwang Li <limingwang@xxxxxxxxxx>
> Reviewed-by: Anup Patel <anup.patel@xxxxxxx>

Acked-by: Alistair Francis <alistair.francis@xxxxxxx>

Alistair

> ---
>  target/riscv/cpu.h |  7 +++++
>  target/riscv/kvm.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 79 insertions(+)
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 5f54fae7cc..9eceded96c 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -261,6 +261,13 @@ struct CPURISCVState {
>
>      hwaddr kernel_addr;
>      hwaddr fdt_addr;
> +
> +    /* kvm timer */
> +    bool kvm_timer_dirty;
> +    uint64_t kvm_timer_time;
> +    uint64_t kvm_timer_compare;
> +    uint64_t kvm_timer_state;
> +    uint64_t kvm_timer_frequency;
>  };
>
>  OBJECT_DECLARE_TYPE(RISCVCPU, RISCVCPUClass,
> diff --git a/target/riscv/kvm.c b/target/riscv/kvm.c
> index ded2a8c29d..b1f1d55f29 100644
> --- a/target/riscv/kvm.c
> +++ b/target/riscv/kvm.c
> @@ -40,6 +40,7 @@
>  #include "kvm_riscv.h"
>  #include "sbi_ecall_interface.h"
>  #include "chardev/char-fe.h"
> +#include "migration/migration.h"
>
>  static uint64_t kvm_riscv_reg_id(CPURISCVState *env, uint64_t type, uint64_t idx)
>  {
> @@ -64,6 +65,9 @@ static uint64_t kvm_riscv_reg_id(CPURISCVState *env, uint64_t type, uint64_t idx
>  #define RISCV_CSR_REG(env, name)  kvm_riscv_reg_id(env, KVM_REG_RISCV_CSR, \
>                   KVM_REG_RISCV_CSR_REG(name))
>
> +#define RISCV_TIMER_REG(env, name)  kvm_riscv_reg_id(env, KVM_REG_RISCV_TIMER, \
> +                 KVM_REG_RISCV_TIMER_REG(name))
> +
>  #define RISCV_FP_F_REG(env, idx)  kvm_riscv_reg_id(env, KVM_REG_RISCV_FP_F, idx)
>
>  #define RISCV_FP_D_REG(env, idx)  kvm_riscv_reg_id(env, KVM_REG_RISCV_FP_D, idx)
> @@ -84,6 +88,22 @@ static uint64_t kvm_riscv_reg_id(CPURISCVState *env, uint64_t type, uint64_t idx
>          } \
>      } while(0)
>
> +#define KVM_RISCV_GET_TIMER(cs, env, name, reg) \
> +    do { \
> +        int ret = kvm_get_one_reg(cs, RISCV_TIMER_REG(env, name), &reg); \
> +        if (ret) { \
> +            abort(); \
> +        } \
> +    } while(0)
> +
> +#define KVM_RISCV_SET_TIMER(cs, env, name, reg) \
> +    do { \
> +        int ret = kvm_set_one_reg(cs, RISCV_TIMER_REG(env, time), &reg); \
> +        if (ret) { \
> +            abort(); \
> +        } \
> +    } while (0)
> +
>  static int kvm_riscv_get_regs_core(CPUState *cs)
>  {
>      int ret = 0;
> @@ -235,6 +255,58 @@ static int kvm_riscv_put_regs_fp(CPUState *cs)
>      return ret;
>  }
>
> +static void kvm_riscv_get_regs_timer(CPUState *cs)
> +{
> +    CPURISCVState *env = &RISCV_CPU(cs)->env;
> +
> +    if (env->kvm_timer_dirty) {
> +        return;
> +    }
> +
> +    KVM_RISCV_GET_TIMER(cs, env, time, env->kvm_timer_time);
> +    KVM_RISCV_GET_TIMER(cs, env, compare, env->kvm_timer_compare);
> +    KVM_RISCV_GET_TIMER(cs, env, state, env->kvm_timer_state);
> +    KVM_RISCV_GET_TIMER(cs, env, frequency, env->kvm_timer_frequency);
> +
> +    env->kvm_timer_dirty = true;
> +}
> +
> +static void kvm_riscv_put_regs_timer(CPUState *cs)
> +{
> +    uint64_t reg;
> +    CPURISCVState *env = &RISCV_CPU(cs)->env;
> +
> +    if (!env->kvm_timer_dirty) {
> +        return;
> +    }
> +
> +    KVM_RISCV_SET_TIMER(cs, env, time, env->kvm_timer_time);
> +    KVM_RISCV_SET_TIMER(cs, env, compare, env->kvm_timer_compare);
> +
> +    /*
> +     * To set register of RISCV_TIMER_REG(state) will occur a error from KVM
> +     * on env->kvm_timer_state == 0, It's better to adapt in KVM, but it
> +     * doesn't matter that adaping in QEMU now.
> +     * TODO If KVM changes, adapt here.
> +     */
> +    if (env->kvm_timer_state) {
> +        KVM_RISCV_SET_TIMER(cs, env, state, env->kvm_timer_state);
> +    }
> +
> +    /*
> +     * For now, migration will not work between Hosts with different timer
> +     * frequency. Therefore, we should check whether they are the same here
> +     * during the migration.
> +     */
> +    if (migration_is_running(migrate_get_current()->state)) {
> +        KVM_RISCV_GET_TIMER(cs, env, frequency, reg);
> +        if (reg != env->kvm_timer_frequency) {
> +            error_report("Dst Hosts timer frequency != Src Hosts");
> +        }
> +    }
> +
> +    env->kvm_timer_dirty = false;
> +}
>
>  const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
>      KVM_CAP_LAST_INFO
> --
> 2.19.1
>
>