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

From: Igor Mammedov <imammedo@redhat.com>
To: Beata Michalska <beata.michalska@linaro.org>
Cc: Xiang Zheng <zhengxiang9@huawei.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	ehabkost@redhat.com, kvm@vger.kernel.org, mst@redhat.com,
	wanghaibin.wang@huawei.com, mtosatti@redhat.com,
	linuxarm@huawei.com, qemu-devel@nongnu.org,
	gengdongjiu@huawei.com, shannon.zhaosl@gmail.com,
	qemu-arm@nongnu.org, james.morse@arm.com, xuwei5@huawei.com,
	jonathan.cameron@huawei.com, pbonzini@redhat.com,
	Laszlo Ersek <lersek@redhat.com>,
	rth@twiddle.net
Subject: Re: [RESEND PATCH v21 5/6] target-arm: kvm64: handle SIGBUS signal from kernel or KVM
Date: Mon, 25 Nov 2019 10:37:06 +0100	[thread overview]
Message-ID: <20191125103706.46300ff1@redhat.com> (raw)
In-Reply-To: <CADSWDzsg9aMCbbLadmc+twmJw3dZvRYgqKKWsDQRiJSRS7=GDQ@mail.gmail.com>

On Fri, 22 Nov 2019 15:47:24 +0000
Beata Michalska <beata.michalska@linaro.org> wrote:

> Hi,
> 
> On Fri, 15 Nov 2019 at 16:54, Igor Mammedov <imammedo@redhat.com> wrote:
> >
> > On Mon, 11 Nov 2019 09:40:47 +0800
> > 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>
> > > ---
> > >  hw/acpi/acpi_ghes.c         | 297 ++++++++++++++++++++++++++++++++++++
[...]
> > > +static int acpi_ghes_record_mem_error(uint64_t error_block_address,
> > > +                                      uint64_t error_physical_addr,
> > > +                                      uint32_t data_length)
> > > +{
> > > +    GArray *block;
> > > +    uint64_t current_block_length;
> > > +    /* Memory Error Section Type */
> > > +    QemuUUID mem_section_id_le = UEFI_CPER_SEC_PLATFORM_MEM;  
> >                                ^^
> > UEFI_CPER_SEC_PLATFORM_MEM is defined as BE, so _le here is wrong
> > and then later you use qemu_uuid_bswap() to make it LE.
> >
> > Why not define it as LE to begin with, like it's been done for NVDIMM_UUID_LE?
> >  
> Is there a chance to make it common for both ?

sure, it just should be a separate patch.

Maybe put it in include/qemu/uuid.h
or maybe make qemu_uuid_parse() return QemuUUID
so we could initialize like this:
  QemuUUID mem_section_id_le = qemu_uuid_parse("00000000-0000-0000-0000-000000000000", &error_abort);
where used UUID value is easy to read and compare with spec.

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