Date: Mon, 17 Jan 2022 16:22:15 GMT From: Emmanuel Vadot <manu@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: e6674c8f7fe7 - stable/13 - bhyve: allow reading of fwctl signature multiple times Message-ID: <202201171622.20HGMFkj017426@gitrepo.freebsd.org>
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The branch stable/13 has been updated by manu: URL: https://cgit.FreeBSD.org/src/commit/?id=e6674c8f7fe765aa72f99bff9bab381737bac896 commit e6674c8f7fe765aa72f99bff9bab381737bac896 Author: Corvin Köhne <CorvinK@beckhoff.com> AuthorDate: 2022-01-03 13:18:31 +0000 Commit: Emmanuel Vadot <manu@FreeBSD.org> CommitDate: 2022-01-17 12:53:17 +0000 bhyve: allow reading of fwctl signature multiple times At the moment, you only have one single chance to read the fwctl signature. At boot bhyve is in the state IDENT_WAIT. It's then possible to switch to IDENT_SEND. After bhyve sends the signature, it switches to REQ. From now on it's impossible to switch back to IDENT_SEND to read the signature. For that reason, only a single driver can read the signature. A guest can't use two drivers to identify that fwctl is present. It gets even worse when using OVMF. OVMF uses a library to access fwctl. Therefore, every single OVMF driver would try to read the signature. Currently, only a single OVMF driver accesses the fwctl. So, there's no issue with it yet. However, no OS driver would have a chance to detect fwctl when using OVMF because it's signature was already consumed by OVMF. Reviewed by: markj MFC after: 2 weeks Sponsored by: Beckhoff Automation GmbH & Co. KG Differential Revision: https://reviews.freebsd.org/D31981 (cherry picked from commit 8ec366ec6c943550a011effe50bc73e3875f8ead) --- usr.sbin/bhyve/fwctl.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/usr.sbin/bhyve/fwctl.c b/usr.sbin/bhyve/fwctl.c index 0640bc28ba2b..abb234fe1de4 100644 --- a/usr.sbin/bhyve/fwctl.c +++ b/usr.sbin/bhyve/fwctl.c @@ -472,16 +472,18 @@ fwctl_inb(void) static void fwctl_outw(uint16_t val) { - switch (be_state) { - case IDENT_WAIT: - if (val == 0) { - be_state = IDENT_SEND; - ident_idx = 0; - } - break; - default: - /* ignore */ - break; + if (be_state == DORMANT) { + return; + } + + if (val == 0) { + /* + * The guest wants to read the signature. It's possible that the + * guest is unaware of the fwctl state at this moment. For that + * reason, reset the state machine unconditionally. + */ + be_state = IDENT_SEND; + ident_idx = 0; } }
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