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author | Paul Mackerras <paulus@samba.org> | 2013-08-06 08:15:19 +0400 |
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committer | Alexander Graf <agraf@suse.de> | 2013-08-28 18:47:49 +0400 |
commit | 8b23de29489fd63fce753db9d53055e4bbf8f616 (patch) | |
tree | 94e266d8d7029bbb411568454d0c4df56b52d5fd /Documentation/trace/ftrace.txt | |
parent | 9d1ffdd8f34b1f89264effd10e75ea4d6272690e (diff) | |
download | linux-8b23de29489fd63fce753db9d53055e4bbf8f616.tar.xz |
KVM: PPC: Book3S PR: Make instruction fetch fallback work for system calls
It turns out that if we exit the guest due to a hcall instruction (sc 1),
and the loading of the instruction in the guest exit path fails for any
reason, the call to kvmppc_ld() in kvmppc_get_last_inst() fetches the
instruction after the hcall instruction rather than the hcall itself.
This in turn means that the instruction doesn't get recognized as an
hcall in kvmppc_handle_exit_pr() but gets passed to the guest kernel
as a sc instruction. That usually results in the guest kernel getting
a return code of 38 (ENOSYS) from an hcall, which often triggers a
BUG_ON() or other failure.
This fixes the problem by adding a new variant of kvmppc_get_last_inst()
called kvmppc_get_last_sc(), which fetches the instruction if necessary
from pc - 4 rather than pc.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'Documentation/trace/ftrace.txt')
0 files changed, 0 insertions, 0 deletions