Hello, On Mon, Jul 18, 2016 at 09:54:39AM +0200, Cornelia Huck wrote: > On Mon, 18 Jul 2016 13:37:39 +0900 > Namhyung Kim <namhyung@xxxxxxxxxx> 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. Thanks! > > > > > 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? Yep, there's no restriction AFAIK. I just choose it to implement the poc code quickly. > > > 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 <pbonzini@xxxxxxxxxx> > > Cc: Radim Kr??m???? <rkrcmar@xxxxxxxxxx> > > Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx> > > Cc: Anthony Liguori <aliguori@xxxxxxxxxx> > > Cc: Anton Vorontsov <anton@xxxxxxxxxx> > > Cc: Colin Cross <ccross@xxxxxxxxxxx> > > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > > Cc: Tony Luck <tony.luck@xxxxxxxxx> > > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > > Cc: Minchan Kim <minchan@xxxxxxxxxx> > > Cc: kvm@xxxxxxxxxxxxxxx > > Cc: qemu-devel@xxxxxxxxxx > > Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx > > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx> > > --- > > 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. Right. I'm considering it too, but it needs a buffer larger than kmsg_bytes (= 10K) to work properly in the current implementation. As this version is just to verify the idea is sane and useful, I used a fixed size buffer. Will change in the next version. > > (...) > > > 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. Ok, will update. > > 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? I'd love to. As I mentioned earlier, I don't have enough knowledge in this area. Could you please provide some links about how can I do that? Thanks, Namhyung -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
