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d="scan'208";a="5924842" From: Paul Durrant To: , Date: Wed, 18 Sep 2019 12:57:44 +0100 Message-ID: <20190918115745.39006-1-paul.durrant@citrix.com> X-Mailer: git-send-email 2.20.1.2.gb21ebb671 MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x X-Received-From: 216.71.155.168 Subject: [Qemu-devel] [PATCH] xen-bus: only set the xen device frontend state if it is missing X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Anthony Perard , Paul Durrant , Stefano Stabellini , Mark Syms Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Mark Syms Some toolstack implementations will set the frontend xenstore keys to Initialising which will then trigger the in guest PV drivers to begin initialising and some implementations will then set their state to Closing. If this has occurred then device realize must not overwrite the frontend keys as then the handshake will stall. Signed-off-by: Mark Syms Also avoid creating the frontend area if it already exists. Signed-off-by: Paul Durrant Reviewed-by: Anthony PERARD --- Cc: Stefano Stabellini Cc: Anthony Perard --- hw/xen/xen-bus.c | 47 +++++++++++++++++++++++++++++++---------------- 1 file changed, 31 insertions(+), 16 deletions(-) diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index 55c157393d..c2ad22a42d 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -857,6 +857,13 @@ static void xen_device_frontend_changed(void *opaque) } } +static bool xen_device_frontend_exists(XenDevice *xendev) +{ + enum xenbus_state state; + + return (xen_device_frontend_scanf(xendev, "state", "%u", &state) == 1); +} + static void xen_device_frontend_create(XenDevice *xendev, Error **errp) { XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev))); @@ -865,19 +872,25 @@ static void xen_device_frontend_create(XenDevice *xendev, Error **errp) xendev->frontend_path = xen_device_get_frontend_path(xendev); - perms[0].id = xendev->frontend_id; - perms[0].perms = XS_PERM_NONE; - perms[1].id = xenbus->backend_id; - perms[1].perms = XS_PERM_READ | XS_PERM_WRITE; + /* + * The frontend area may have already been created by a legacy + * toolstack. + */ + if (!xen_device_frontend_exists(xendev)) { + perms[0].id = xendev->frontend_id; + perms[0].perms = XS_PERM_NONE; + perms[1].id = xenbus->backend_id; + perms[1].perms = XS_PERM_READ | XS_PERM_WRITE; - g_assert(xenbus->xsh); + g_assert(xenbus->xsh); - xs_node_create(xenbus->xsh, XBT_NULL, xendev->frontend_path, perms, - ARRAY_SIZE(perms), &local_err); - if (local_err) { - error_propagate_prepend(errp, local_err, - "failed to create frontend: "); - return; + xs_node_create(xenbus->xsh, XBT_NULL, xendev->frontend_path, perms, + ARRAY_SIZE(perms), &local_err); + if (local_err) { + error_propagate_prepend(errp, local_err, + "failed to create frontend: "); + return; + } } xendev->frontend_state_watch = @@ -1290,12 +1303,14 @@ static void xen_device_realize(DeviceState *dev, Error **errp) xen_device_backend_set_online(xendev, true); xen_device_backend_set_state(xendev, XenbusStateInitWait); - xen_device_frontend_printf(xendev, "backend", "%s", - xendev->backend_path); - xen_device_frontend_printf(xendev, "backend-id", "%u", - xenbus->backend_id); + if (!xen_device_frontend_exists(xendev)) { + xen_device_frontend_printf(xendev, "backend", "%s", + xendev->backend_path); + xen_device_frontend_printf(xendev, "backend-id", "%u", + xenbus->backend_id); - xen_device_frontend_set_state(xendev, XenbusStateInitialising, true); + xen_device_frontend_set_state(xendev, XenbusStateInitialising, true); + } xendev->exit.notify = xen_device_exit; qemu_add_exit_notifier(&xendev->exit);