Re: [RESEND PATCH v21 5/6] target-arm: kvm64: handle SIGBUS signal from kernel or KVM

[Xiang Zheng]

On 2019/11/27 22:17, Beata Michalska wrote:
> On Wed, 27 Nov 2019 at 13:03, Igor Mammedov <address@hidden> wrote:
>>
>> On Wed, 27 Nov 2019 20:47:15 +0800
>> Xiang Zheng <address@hidden> wrote:
>>
>>> Hi Beata,
>>>
>>> Thanks for you review!
>>>
>>> On 2019/11/22 23:47, Beata Michalska wrote:
>>>> Hi,
>>>>
>>>> On Mon, 11 Nov 2019 at 01:48, Xiang Zheng <address@hidden> wrote:
>>>>>
>>>>> From: Dongjiu Geng <address@hidden>
>>>>>
>>>>> Add a SIGBUS signal handler. In this handler, it checks the SIGBUS type,
>>>>> translates the host VA delivered by host to guest PA, then fills this PA
>>>>> to guest APEI GHES memory, then notifies guest according to the SIGBUS
>>>>> type.
>>>>>
>>>>> When guest accesses the poisoned memory, it will generate a Synchronous
>>>>> External Abort(SEA). Then host kernel gets an APEI notification and calls
>>>>> memory_failure() to unmapped the affected page in stage 2, finally
>>>>> returns to guest.
>>>>>
>>>>> Guest continues to access the PG_hwpoison page, it will trap to KVM as
>>>>> stage2 fault, then a SIGBUS_MCEERR_AR synchronous signal is delivered to
>>>>> Qemu, Qemu records this error address into guest APEI GHES memory and
>>>>> notifes guest using Synchronous-External-Abort(SEA).
>>>>>
>>>>> In order to inject a vSEA, we introduce the kvm_inject_arm_sea() function
>>>>> in which we can setup the type of exception and the syndrome information.
>>>>> When switching to guest, the target vcpu will jump to the synchronous
>>>>> external abort vector table entry.
>>>>>
>>>>> The ESR_ELx.DFSC is set to synchronous external abort(0x10), and the
>>>>> ESR_ELx.FnV is set to not valid(0x1), which will tell guest that FAR is
>>>>> not valid and hold an UNKNOWN value. These values will be set to KVM
>>>>> register structures through KVM_SET_ONE_REG IOCTL.
>>>>>
>>>>> Signed-off-by: Dongjiu Geng <address@hidden>
>>>>> Signed-off-by: Xiang Zheng <address@hidden>
>>>>> Reviewed-by: Michael S. Tsirkin <address@hidden>
>>>>> ---
>> [...]
>>>>> diff --git a/include/hw/acpi/acpi_ghes.h b/include/hw/acpi/acpi_ghes.h
>>>>> index cb62ec9c7b..8e3c5b879e 100644
>>>>> --- a/include/hw/acpi/acpi_ghes.h
>>>>> +++ b/include/hw/acpi/acpi_ghes.h
>>>>> @@ -24,6 +24,9 @@
>>>>>
>>>>>  #include "hw/acpi/bios-linker-loader.h"
>>>>>
>>>>> +#define ACPI_GHES_CPER_OK                   1
>>>>> +#define ACPI_GHES_CPER_FAIL                 0
>>>>> +
>>>>
>>>> Is there really a need to introduce those ?
>>>>
>>>
>>> Don't you think it's more clear than using "1" or "0"? :)
>>
>> or maybe just reuse default libc return convention: 0 - ok, -1 - fail
>> and drop custom macros
>>
> 
> Totally agree.
> 

OK, let's reuse default libc return convention.

-- 

Thanks,
Xiang