From mboxrd@z Thu Jan 1 00:00:00 1970 From: mst@redhat.com (Michael S. Tsirkin) Date: Wed, 29 Mar 2017 15:51:44 +0300 Subject: [PATCH] kvm: pass the virtual SEI syndrome to guest OS In-Reply-To: <2a427164-9b37-6711-3a56-906634ba7f12@redhat.com> References: <58D17AF0.2010802@arm.com> <20170321193933.GB31111@cbox> <58DA3F68.6090901@arm.com> <20170328112328.GA31156@cbox> <20170328115413.GJ23682@e104320-lin> <58DA67BA.8070404@arm.com> <5b7352f4-4965-3ed5-3879-db871797be47@huawei.com> <20170329103658.GQ23682@e104320-lin> <2a427164-9b37-6711-3a56-906634ba7f12@redhat.com> Message-ID: <20170329154539-mutt-send-email-mst@kernel.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Mar 29, 2017 at 01:58:29PM +0200, Laszlo Ersek wrote: > (8) When QEMU gets SIGBUS from the kernel -- I hope that's going to come > through a signalfd -- QEMU can format the CPER right into guest memory, > and then inject whatever interrupt (or assert whatever GPIO line) is > necessary for notifying the guest. I think I see a race condition potential - what if guest accesses CPER in guest memory while it's being written? We can probably use another level of indirection to fix this: allocate twice the space, add a pointer to where the valid table is located and update that after writing CPER completely. The pointer can be written atomically but also needs to be read atomically, so I suspect it should be a single byte as we don't know how are OSPMs implementing this. -- MST