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88 lines
3.6 KiB
88 lines
3.6 KiB
9 months ago
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From 27f045e2d52ee49ddbb375b5593d4fc387aad4b0 Mon Sep 17 00:00:00 2001
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From: Jordan Niethe <jniethe5@gmail.com>
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Date: Tue, 29 Aug 2023 10:12:01 +1000
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Subject: [PATCH 2/2] virtio-serial: Do not close stdout on quiesce
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RH-Author: Thomas Huth <thuth@redhat.com>
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RH-MergeRequest: 1: Fix SLOF crash when only using virtio console (without spapr-vty)
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RH-Jira: RHEL-3709
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RH-Acked-by: David Gibson (Red Hat) <dgibson@redhat.com>
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RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
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RH-Commit: [2/2] cbde239703a11aa2676a12b8415281d37cba54a5
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Commit 76fee95 ("slof: Only close stdout for virtio-serial devices")
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says that commit cf28264 ("virtio-serial: Rework shutdown sequence")
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fixed a hang. The problem was believed to be that it was necessary to
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close stdout to shutdown the underlying virtio device.
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Commit cf28264 ("virtio-serial: Rework shutdown sequence") closed stdout
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on quiesce. This meant when prom_init() called write on stdout after
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quiesce, there is a use after free so this is unreliable, and can also
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hang (especially after reboots).
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Quiescing is intended to put hardware into a safe state for the client
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to take over. It is incorrect for SLOF to close ihandles that the client
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could still be using, even after a quiesce.
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Rather than closing the stdout device, all that needs to happen is to
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ensure virtio-serial-shutdown gets called. On quiesce, close the virtio
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device, but leave the stdout device itself open.
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Commit 8174acd ("virtio-serial: Close device completely") handles reads
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and writes as no-ops if the underlying virtio device is closed so there
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is no problem with the client calling "write" on stdout after this, but
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no output will be displayed.
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Fixes: cf28264 ("virtio-serial: Rework shutdown sequence")
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Debugged-by: Kautuk Consul <kconsul@linux.vnet.ibm.com>
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Co-developed-by: Kautuk Consul <kconsul@linux.vnet.ibm.com>
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Signed-off-by: Kautuk Consul <kconsul@linux.vnet.ibm.com>
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Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
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Reviewed-by: Thomas Huth <thuth@redhat.com>
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Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
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(cherry picked from commit dd4d4ea0add97df078d571b48192adaf7c4b0d87)
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Jira: https://issues.redhat.com/browse/RHEL-3709
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Signed-off-by: Thomas Huth <thuth@redhat.com>
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---
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board-qemu/slof/virtio-serial.fs | 12 +++++-------
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1 file changed, 5 insertions(+), 7 deletions(-)
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diff --git a/board-qemu/slof/virtio-serial.fs b/board-qemu/slof/virtio-serial.fs
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index 41e2e04..de42cc7 100644
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--- a/board-qemu/slof/virtio-serial.fs
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+++ b/board-qemu/slof/virtio-serial.fs
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@@ -33,16 +33,14 @@ virtio-setup-vd VALUE virtiodev
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: virtio-serial-term-key? virtiodev virtio-serial-haschar ;
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: virtio-serial-term-key BEGIN virtio-serial-term-key? UNTIL virtiodev virtio-serial-getchar ;
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-: virtio-serial-close-stdout s" stdout" get-chosen IF decode-int nip nip close-dev THEN ;
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-
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\ Basic device initialization - which has only to be done once
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: init ( -- )
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virtiodev virtio-serial-init drop
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TRUE to initialized?
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- \ Linux closes stdin at some point in prom_init(). This internally triggers a
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- \ quiesce in SLOF. We must ensure stdout gets closed as well otherwise the
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- \ device cannot be reset properly and the boot will hang.
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- ['] virtio-serial-close-stdout add-quiesce-xt
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+ \ virtiodev must be shutdown at quiesce so the device is reset properly.
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+ \ The read and write methods can be called after quiesce so must handle
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+ \ virtiodev being closed.
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+ ['] shutdown add-quiesce-xt
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;
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0 VALUE open-count
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@@ -62,8 +60,8 @@ virtiodev virtio-serial-init drop
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open-count 0> IF
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open-count 1 - dup to open-count
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0= IF shutdown THEN
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+ close
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THEN
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- close
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;
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: write ( addr len -- actual )
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--
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2.41.0
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