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

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 27 Nov 2019 20:47:15 +0800
Xiang Zheng <zhengxiang9@huawei.com> 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 <zhengxiang9@huawei.com> wrote:  
> >>
> >> From: Dongjiu Geng <gengdongjiu@huawei.com>
> >>
> >> 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 <gengdongjiu@huawei.com>
> >> Signed-off-by: Xiang Zheng <zhengxiang9@huawei.com>
> >> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> >> ---
[...]
> >> 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

> 
> >>  /*
> >>   * Values for Hardware Error Notification Type field
> >>   */
[...]