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| author | Michael Roth <mdroth@linux.vnet.ibm.com> | 2020-03-10 16:11:28 -0500 |
|---|---|---|
| committer | Paul Mackerras <paulus@ozlabs.org> | 2020-03-19 16:39:52 +1100 |
| commit | 1f50cc1705350a4697923203fedd7d8fb1087fe2 (patch) | |
| tree | 053d0bb0484b38f45a23ac689dd044dc09cc5da3 | |
| parent | 1dff3064c764b5a51c367b949b341d2e38972bec (diff) | |
| download | linux-1f50cc1705350a4697923203fedd7d8fb1087fe2.tar.gz | |
KVM: PPC: Book3S HV: Fix H_CEDE return code for nested guests
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: 4bad77799fed ("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>
| -rw-r--r-- | arch/powerpc/kvm/book3s_hv.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index fbc55a12b691..18675bd48e90 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3615,6 +3615,7 @@ int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, if (trap == BOOK3S_INTERRUPT_SYSCALL && !vcpu->arch.nested && kvmppc_get_gpr(vcpu, 3) == H_CEDE) { kvmppc_nested_cede(vcpu); + kvmppc_set_gpr(vcpu, 3, 0); trap = 0; } } else { |