Re: [PATCH v9 06/15] s390x: Add SIDA memory ops

[Christian Borntraeger]

On 11.03.20 14:21, Janosch Frank wrote:
> Protected guests save the instruction control blocks in the SIDA
> instead of QEMU/KVM directly accessing the guest's memory.
> 
> Let's introduce new functions to access the SIDA.
> 
> Also the new memops are available with KVM_CAP_S390_PROTECTED, so
> let's check for that.
> 
> Signed-off-by: Janosch Frank <address@hidden>
> Reviewed-by: David Hildenbrand <address@hidden>

Reviewed-by: Christian Borntraeger <address@hidden>

> ---
>  target/s390x/cpu.h        |  7 ++++++-
>  target/s390x/kvm.c        | 25 +++++++++++++++++++++++++
>  target/s390x/kvm_s390x.h  |  2 ++
>  target/s390x/mmu_helper.c | 14 ++++++++++++++
>  4 files changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> index 1d17709d6e10b5e0..035427521cec2528 100644
> --- a/target/s390x/cpu.h
> +++ b/target/s390x/cpu.h
> @@ -823,7 +823,12 @@ int s390_cpu_virt_mem_rw(S390CPU *cpu, vaddr laddr, 
> uint8_t ar, void *hostbuf,
>  #define s390_cpu_virt_mem_check_write(cpu, laddr, ar, len)   \
>          s390_cpu_virt_mem_rw(cpu, laddr, ar, NULL, len, true)
>  void s390_cpu_virt_mem_handle_exc(S390CPU *cpu, uintptr_t ra);
> -
> +int s390_cpu_pv_mem_rw(S390CPU *cpu, unsigned int offset, void *hostbuf,
> +                       int len, bool is_write);
> +#define s390_cpu_pv_mem_read(cpu, offset, dest, len)    \
> +        s390_cpu_pv_mem_rw(cpu, offset, dest, len, false)
> +#define s390_cpu_pv_mem_write(cpu, offset, dest, len)       \
> +        s390_cpu_pv_mem_rw(cpu, offset, dest, len, true)
>  
>  /* sigp.c */
>  int s390_cpu_restart(S390CPU *cpu);
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index eec0b92479465b9c..cdcd538b4f7fb318 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -154,6 +154,7 @@ static int cap_ri;
>  static int cap_gs;
>  static int cap_hpage_1m;
>  static int cap_vcpu_resets;
> +static int cap_protected;
>  
>  static int active_cmma;
>  
> @@ -346,6 +347,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
>      cap_mem_op = kvm_check_extension(s, KVM_CAP_S390_MEM_OP);
>      cap_s390_irq = kvm_check_extension(s, KVM_CAP_S390_INJECT_IRQ);
>      cap_vcpu_resets = kvm_check_extension(s, KVM_CAP_S390_VCPU_RESETS);
> +    cap_protected = kvm_check_extension(s, KVM_CAP_S390_PROTECTED);
>  
>      if (!kvm_check_extension(s, KVM_CAP_S390_GMAP)
>          || !kvm_check_extension(s, KVM_CAP_S390_COW)) {
> @@ -846,6 +848,29 @@ int kvm_s390_mem_op(S390CPU *cpu, vaddr addr, uint8_t 
> ar, void *hostbuf,
>      return ret;
>  }
>  
> +int kvm_s390_mem_op_pv(S390CPU *cpu, uint64_t offset, void *hostbuf,
> +                       int len, bool is_write)
> +{
> +    struct kvm_s390_mem_op mem_op = {
> +        .sida_offset = offset,
> +        .size = len,
> +        .op = is_write ? KVM_S390_MEMOP_SIDA_WRITE
> +                       : KVM_S390_MEMOP_SIDA_READ,
> +        .buf = (uint64_t)hostbuf,
> +    };
> +    int ret;
> +
> +    if (!cap_mem_op || !cap_protected) {
> +        return -ENOSYS;
> +    }
> +
> +    ret = kvm_vcpu_ioctl(CPU(cpu), KVM_S390_MEM_OP, &mem_op);
> +    if (ret < 0) {
> +        error_report("KVM_S390_MEM_OP failed: %s", strerror(-ret));
> +    }
> +    return ret;
> +}
> +
>  /*
>   * Legacy layout for s390:
>   * Older S390 KVM requires the topmost vma of the RAM to be
> diff --git a/target/s390x/kvm_s390x.h b/target/s390x/kvm_s390x.h
> index 0b21789796d7c462..9c38f6ccce83e39e 100644
> --- a/target/s390x/kvm_s390x.h
> +++ b/target/s390x/kvm_s390x.h
> @@ -19,6 +19,8 @@ void kvm_s390_vcpu_interrupt(S390CPU *cpu, struct 
> kvm_s390_irq *irq);
>  void kvm_s390_access_exception(S390CPU *cpu, uint16_t code, uint64_t 
> te_code);
>  int kvm_s390_mem_op(S390CPU *cpu, vaddr addr, uint8_t ar, void *hostbuf,
>                      int len, bool is_write);
> +int kvm_s390_mem_op_pv(S390CPU *cpu, vaddr addr, void *hostbuf, int len,
> +                       bool is_write);
>  void kvm_s390_program_interrupt(S390CPU *cpu, uint16_t code);
>  int kvm_s390_set_cpu_state(S390CPU *cpu, uint8_t cpu_state);
>  void kvm_s390_vcpu_interrupt_pre_save(S390CPU *cpu);
> diff --git a/target/s390x/mmu_helper.c b/target/s390x/mmu_helper.c
> index 0be2f300bbe4ac8b..7d9f3059cd502c49 100644
> --- a/target/s390x/mmu_helper.c
> +++ b/target/s390x/mmu_helper.c
> @@ -474,6 +474,20 @@ static int translate_pages(S390CPU *cpu, vaddr addr, int 
> nr_pages,
>      return 0;
>  }
>  
> +int s390_cpu_pv_mem_rw(S390CPU *cpu, unsigned int offset, void *hostbuf,
> +                       int len, bool is_write)
> +{
> +    int ret;
> +
> +    if (kvm_enabled()) {
> +        ret = kvm_s390_mem_op_pv(cpu, offset, hostbuf, len, is_write);
> +    } else {
> +        /* Protected Virtualization is a KVM/Hardware only feature */
> +        g_assert_not_reached();
> +    }
> +    return ret;
> +}
> +
>  /**
>   * s390_cpu_virt_mem_rw:
>   * @laddr:     the logical start address
>