On 11/03/13 18:58, Jason J. Herne wrote:
> We want to avoid expensive register synchronization IOCTL's on the hot path so
> a new kvm_s390_get_registers_partial() is introduced as a compliment to
> kvm_arch_get_registers(). The new function is called on the hot path, and
> kvm_arch_get_registers() is called when we need the complete runtime register
> state.
>
> kvm_arch_put_registers() is updated to only sync the partial runtime set when
> we've only dirtied the partial runtime set. This is to avoid sending bad data
> back to KVM if we've only partially synced the runtime register set.
>
> Signed-off-by: Jason J. Herne <jjhe...@us.ibm.com>
> Reviewed-by: Christian Borntraeger <borntrae...@de.ibm.com>
Alex,
we have this code in our private tree (the one thats used by the testers) for a
while
now and it seems to work fine.
This should be ok to apply.
Since this also fixes the problem that s390 has not a complete view of the kvm
registers
in places were we want it (dump etc) we might even consider this a bugfix.
Your take if this is still good for 1.5.
Christian
> ---
> target-s390x/cpu.h | 17 +++++++++++++
> target-s390x/kvm.c | 67
> ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 84 insertions(+)
>
> diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
> index 9cb739d..69ecb05 100644
> --- a/target-s390x/cpu.h
> +++ b/target-s390x/cpu.h
> @@ -78,6 +78,11 @@ typedef struct MchkQueue {
> uint16_t type;
> } MchkQueue;
>
> +/* Defined values for CPUS390XState.runtime_reg_dirty_mask */
> +#define KVM_S390_RUNTIME_DIRTY_NONE 0
> +#define KVM_S390_RUNTIME_DIRTY_PARTIAL 1
> +#define KVM_S390_RUNTIME_DIRTY_FULL 2
> +
> typedef struct CPUS390XState {
> uint64_t regs[16]; /* GP registers */
> CPU_DoubleU fregs[16]; /* FP registers */
> @@ -121,6 +126,13 @@ typedef struct CPUS390XState {
> uint64_t cputm;
> uint32_t todpr;
>
> + /* on S390 the runtime register set has two dirty states:
> + * a partial dirty state in which only the registers that
> + * are needed all the time are fetched. And a fully dirty
> + * state in which all runtime registers are fetched.
> + */
> + uint32_t runtime_reg_dirty_mask;
> +
> CPU_COMMON
>
> /* reset does memset(0) up to here */
> @@ -1068,6 +1080,7 @@ void kvm_s390_io_interrupt(S390CPU *cpu, uint16_t
> subchannel_id,
> uint32_t io_int_word);
> void kvm_s390_crw_mchk(S390CPU *cpu);
> void kvm_s390_enable_css_support(S390CPU *cpu);
> +int kvm_s390_get_registers_partial(CPUState *cpu);
> #else
> static inline void kvm_s390_io_interrupt(S390CPU *cpu,
> uint16_t subchannel_id,
> @@ -1082,6 +1095,10 @@ static inline void kvm_s390_crw_mchk(S390CPU *cpu)
> static inline void kvm_s390_enable_css_support(S390CPU *cpu)
> {
> }
> +static inline int kvm_s390_get_registers_partial(CPUState *cpu)
> +{
> + return -ENOSYS;
> +}
> #endif
>
> static inline void s390_io_interrupt(S390CPU *cpu,
> diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
> index 8f111ae..934757e 100644
> --- a/target-s390x/kvm.c
> +++ b/target-s390x/kvm.c
> @@ -123,6 +123,7 @@ int kvm_arch_put_registers(CPUState *cs, int level)
> {
> S390CPU *cpu = S390_CPU(cs);
> CPUS390XState *env = &cpu->env;
> + struct kvm_one_reg reg;
> struct kvm_sregs sregs;
> struct kvm_regs regs;
> int ret;
> @@ -147,6 +148,30 @@ int kvm_arch_put_registers(CPUState *cs, int level)
> }
> }
>
> + if (env->runtime_reg_dirty_mask == KVM_S390_RUNTIME_DIRTY_FULL) {
> + reg.id = KVM_REG_S390_CPU_TIMER;
> + reg.addr = (__u64)&(env->cputm);
> + ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, ®);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + reg.id = KVM_REG_S390_CLOCK_COMP;
> + reg.addr = (__u64)&(env->ckc);
> + ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, ®);
> + if (ret < 0) {
> + return ret;
> + }
> +
> + reg.id = KVM_REG_S390_TODPR;
> + reg.addr = (__u64)&(env->todpr);
> + ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, ®);
> + if (ret < 0) {
> + return ret;
> + }
> + }
> + env->runtime_reg_dirty_mask = KVM_S390_RUNTIME_DIRTY_NONE;
> +
> /* Do we need to save more than that? */
> if (level == KVM_PUT_RUNTIME_STATE) {
> return 0;
> @@ -186,11 +211,52 @@ int kvm_arch_get_registers(CPUState *cs)
> {
> S390CPU *cpu = S390_CPU(cs);
> CPUS390XState *env = &cpu->env;
> + struct kvm_one_reg reg;
> + int r;
> +
> + r = kvm_s390_get_registers_partial(cs);
> + if (r < 0) {
> + return r;
> + }
> +
> + reg.id = KVM_REG_S390_CPU_TIMER;
> + reg.addr = (__u64)&(env->cputm);
> + r = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, ®);
> + if (r < 0) {
> + return r;
> + }
> +
> + reg.id = KVM_REG_S390_CLOCK_COMP;
> + reg.addr = (__u64)&(env->ckc);
> + r = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, ®);
> + if (r < 0) {
> + return r;
> + }
> +
> + reg.id = KVM_REG_S390_TODPR;
> + reg.addr = (__u64)&(env->todpr);
> + r = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, ®);
> + if (r < 0) {
> + return r;
> + }
> +
> + env->runtime_reg_dirty_mask = KVM_S390_RUNTIME_DIRTY_FULL;
> + return 0;
> +}
> +
> +int kvm_s390_get_registers_partial(CPUState *cs)
> +{
> + S390CPU *cpu = S390_CPU(cs);
> + CPUS390XState *env = &cpu->env;
> struct kvm_sregs sregs;
> struct kvm_regs regs;
> int ret;
> int i;
>
> + if (env->runtime_reg_dirty_mask) {
> + return 0;
> + }
> +
> /* get the PSW */
> env->psw.addr = cs->kvm_run->psw_addr;
> env->psw.mask = cs->kvm_run->psw_mask;
> @@ -236,6 +302,7 @@ int kvm_arch_get_registers(CPUState *cs)
> /* no prefix without sync regs */
> }
>
> + env->runtime_reg_dirty_mask = KVM_S390_RUNTIME_DIRTY_PARTIAL;
> return 0;
> }
>
