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[ Upstream commit1f50cc1705] The h_cede_tm kvm-unit-test currently fails when run inside an L1 guest via the guest/nested hypervisor. ./run-tests.sh -v ... TESTNAME=h_cede_tm TIMEOUT=90s ACCEL= ./powerpc/run powerpc/tm.elf -smp 2,threads=2 -machine cap-htm=on -append "h_cede_tm" FAIL h_cede_tm (2 tests, 1 unexpected failures) While the test relates to transactional memory instructions, the actual failure is due to the return code of the H_CEDE hypercall, which is reported as 224 instead of 0. This happens even when no TM instructions are issued. 224 is the value placed in r3 to execute a hypercall for H_CEDE, and r3 is where the caller expects the return code to be placed upon return. In the case of guest running under a nested hypervisor, issuing H_CEDE causes a return from H_ENTER_NESTED. In this case H_CEDE is specially-handled immediately rather than later in kvmppc_pseries_do_hcall() as with most other hcalls, but we forget to set the return code for the caller, hence why kvm-unit-test sees the 224 return code and reports an error. Guest kernels generally don't check the return value of H_CEDE, so that likely explains why this hasn't caused issues outside of kvm-unit-tests so far. Fix this by setting r3 to 0 after we finish processing the H_CEDE. RHBZ: 1778556 Fixes:4bad77799f("KVM: PPC: Book3S HV: Handle hypercalls correctly when nested") Cc: linuxppc-dev@ozlabs.org Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.