On Mon, 18 Jul 2016 13:37:39 +0900 Namhyung Kim <namhy...@kernel.org> wrote:
> The virtio pstore driver provides interface to the pstore subsystem so > that the guest kernel's log/dump message can be saved on the host > machine. Users can access the log file directly on the host, or on the > guest at the next boot using pstore filesystem. It currently deals with > kernel log (printk) buffer only, but we can extend it to have other > information (like ftrace dump) later. Like the idea. > > It supports legacy PCI device using single order-2 page buffer. As all There should not be anything in there that limits this to pci, no? > operation of pstore is synchronous, it would be fine IMHO. However I > don't know how to make write operation synchronous since it's called > with a spinlock held (from any context including NMI). > > Cc: Paolo Bonzini <pbonz...@redhat.com> > Cc: Radim Krčmář <rkrc...@redhat.com> > Cc: "Michael S. Tsirkin" <m...@redhat.com> > Cc: Anthony Liguori <aligu...@amazon.com> > Cc: Anton Vorontsov <an...@enomsg.org> > Cc: Colin Cross <ccr...@android.com> > Cc: Kees Cook <keesc...@chromium.org> > Cc: Tony Luck <tony.l...@intel.com> > Cc: Steven Rostedt <rost...@goodmis.org> > Cc: Ingo Molnar <mi...@kernel.org> > Cc: Minchan Kim <minc...@kernel.org> > Cc: k...@vger.kernel.org > Cc: qemu-devel@nongnu.org > Cc: virtualizat...@lists.linux-foundation.org > Signed-off-by: Namhyung Kim <namhy...@kernel.org> > --- > drivers/virtio/Kconfig | 10 ++ > drivers/virtio/Makefile | 1 + > drivers/virtio/virtio_pstore.c | 317 > +++++++++++++++++++++++++++++++++++++ > include/uapi/linux/Kbuild | 1 + > include/uapi/linux/virtio_ids.h | 1 + > include/uapi/linux/virtio_pstore.h | 53 +++++++ > 6 files changed, 383 insertions(+) > create mode 100644 drivers/virtio/virtio_pstore.c > create mode 100644 include/uapi/linux/virtio_pstore.h > (...) > diff --git a/drivers/virtio/virtio_pstore.c b/drivers/virtio/virtio_pstore.c > new file mode 100644 > index 000000000000..6fe62c0f1508 > --- /dev/null > +++ b/drivers/virtio/virtio_pstore.c > @@ -0,0 +1,317 @@ > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > + > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/pstore.h> > +#include <linux/virtio.h> > +#include <linux/virtio_config.h> > +#include <uapi/linux/virtio_ids.h> > +#include <uapi/linux/virtio_pstore.h> > + > +#define VIRT_PSTORE_ORDER 2 > +#define VIRT_PSTORE_BUFSIZE (4096 << VIRT_PSTORE_ORDER) It may make sense to make the size of the buffer configurable through the config space. (...) > diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h > index 77925f587b15..cba63225d85a 100644 > --- a/include/uapi/linux/virtio_ids.h > +++ b/include/uapi/linux/virtio_ids.h > @@ -41,5 +41,6 @@ > #define VIRTIO_ID_CAIF 12 /* Virtio caif */ > #define VIRTIO_ID_GPU 16 /* virtio GPU */ > #define VIRTIO_ID_INPUT 18 /* virtio input */ > +#define VIRTIO_ID_PSTORE 19 /* virtio pstore */ This id is already used by one of the new device types queued but not yet in the standard. IIRC, 22 is the next free one. Speaking of the standard: I think it makes sense to at least reserve a device id for pstore, as the idea is sound. Maybe prepare a patch to the standard as well if you have time? > > #endif /* _LINUX_VIRTIO_IDS_H */
