Re: [Qemu-devel] [PATCH v2 4/4] spapr: Introduce FWNMI KVM capability

[Alexey Kardashevskiy]

On 17/12/15 15:38, Aravinda Prasad wrote:
> 
> 
> On Thursday 17 December 2015 09:32 AM, David Gibson wrote:
>> On Wed, Dec 16, 2015 at 11:38:47AM +0530, Aravinda Prasad wrote:
>>> Introduce a new KVM capability to control how KVM
>>> behaves on machine check exception.
>>>
>>> Without this capability, KVM redirects machine check
>>> exceptions to guest's 0x200 vector if the address in
>>> error belongs to guest. With this capability KVM
>>> causes a guest exit with NMI exit reason.
>>>
>>> This is required to avoid problem if a new kernel/KVM
>>> is used with an old QEMU. As old QEMU might not
>>> understand the new NMI exit type and treat it as a
>>> fatal error, even though the guest could have actually
>>> handled the error if the exception was delivered to
>>> guest's 0x200 interrupt vector.
>>>
>>> PS: KVM_CAP_PPC_FWNMI is set to 121 as 119 and 120 are
>>> used by KVM_CAP_GUEST_DEBUG_HW_BPS and KVM_CAP_GUEST_DEBUG_HW_WPS
>>> in KVM code, but still not reflected in QEMU code.
>>
>> The commit message seems to be written as if this were the kernel
>> patch adding the capability there, rather than the qemu patch using
>> it.
>>
> 
> I will reword it.


Was there any progress in regard of FWNMI?



> 
> Regards,
> Aravinda
> 
>>> Signed-off-by: Aravinda Prasad <address@hidden>
>>> ---
>>>  hw/ppc/spapr_rtas.c       |   17 +++++++++++++++++
>>>  linux-headers/linux/kvm.h |    1 +
>>>  target-ppc/kvm.c          |    2 ++
>>>  3 files changed, 20 insertions(+)
>>>
>>> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
>>> index 17c4672..53319da 100644
>>> --- a/hw/ppc/spapr_rtas.c
>>> +++ b/hw/ppc/spapr_rtas.c
>>> @@ -38,6 +38,8 @@
>>>  #include <libfdt.h>
>>>  #include "hw/ppc/spapr_drc.h"
>>>  
>>> +extern int cap_fwnmi;
>>> +
>>>  /* #define DEBUG_SPAPR */
>>>  
>>>  #ifdef DEBUG_SPAPR
>>> @@ -603,9 +605,24 @@ static void rtas_ibm_nmi_register(PowerPCCPU *cpu,
>>>                                    target_ulong args,
>>>                                    uint32_t nret, target_ulong rets)
>>>  {
>>> +    int ret;
>>> +    CPUState *cs = CPU(cpu);
>>> +
>>> +    if (!cap_fwnmi) {
>>> +        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
>>> +        return;
>>> +    }
>>> +
>>>      spapr->mc_in_progress = false;
>>>      qemu_cond_init(&spapr->mc_delivery_cond);
>>>      spapr->guest_machine_check_addr = rtas_ld(args, 1);
>>> +
>>> +    ret = kvm_vcpu_enable_cap(cs, KVM_CAP_PPC_FWNMI, 0);
>>> +    if (ret < 0) {
>>> +        rtas_st(rets, 0, RTAS_OUT_HW_ERROR);
>>> +        return;
>>> +    }
>>> +
>>>      rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>>>  }
>>>  
>>> diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
>>> index 683f713..2db1fba 100644
>>> --- a/linux-headers/linux/kvm.h
>>> +++ b/linux-headers/linux/kvm.h
>>> @@ -819,6 +819,7 @@ struct kvm_ppc_smmu_info {
>>>  #define KVM_CAP_DISABLE_QUIRKS 116
>>>  #define KVM_CAP_X86_SMM 117
>>>  #define KVM_CAP_MULTI_ADDRESS_SPACE 118
>>> +#define KVM_CAP_PPC_FWNMI 121
>>>  
>>>  #ifdef KVM_CAP_IRQ_ROUTING
>>>  
>>> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
>>> index 2bbb46d..5339c04 100644
>>> --- a/target-ppc/kvm.c
>>> +++ b/target-ppc/kvm.c
>>> @@ -74,6 +74,7 @@ static int cap_ppc_watchdog;
>>>  static int cap_papr;
>>>  static int cap_htab_fd;
>>>  static int cap_fixup_hcalls;
>>> +int cap_fwnmi;
>>>  
>>>  static uint32_t debug_inst_opcode;
>>>  
>>> @@ -116,6 +117,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
>>>       * only activated after this by kvmppc_set_papr() */
>>>      cap_htab_fd = kvm_check_extension(s, KVM_CAP_PPC_HTAB_FD);
>>>      cap_fixup_hcalls = kvm_check_extension(s, KVM_CAP_PPC_FIXUP_HCALL);
>>> +    cap_fwnmi = kvm_check_extension(s, KVM_CAP_PPC_FWNMI);
>>>  
>>>      if (!cap_interrupt_level) {
>>>          fprintf(stderr, "KVM: Couldn't find level irq capability. Expect 
>>> the "
>>>
>>
> 


-- 
Alexey