diff options
| author | Paul Mackerras <paulus@ozlabs.org> | 2019-08-27 11:35:40 +1000 |
|---|---|---|
| committer | Paul Mackerras <paulus@ozlabs.org> | 2019-08-27 14:08:22 +1000 |
| commit | ff42df49e75f053a8a6b4c2533100cdcc23afe69 (patch) | |
| tree | 7bf50e32722cab25271162d8b9b5098ef8f53994 | |
| parent | d28eafc5a64045c78136162af9d4ba42f8230080 (diff) | |
| download | powerpc-ff42df49e75f053a8a6b4c2533100cdcc23afe69.tar.gz | |
KVM: PPC: Book3S HV: Don't lose pending doorbell request on migration on P9kvm-ppc-next-5.4-1
On POWER9, when userspace reads the value of the DPDES register on a
vCPU, it is possible for 0 to be returned although there is a doorbell
interrupt pending for the vCPU. This can lead to a doorbell interrupt
being lost across migration. If the guest kernel uses doorbell
interrupts for IPIs, then it could malfunction because of the lost
interrupt.
This happens because a newly-generated doorbell interrupt is signalled
by setting vcpu->arch.doorbell_request to 1; the DPDES value in
vcpu->arch.vcore->dpdes is not updated, because it can only be updated
when holding the vcpu mutex, in order to avoid races.
To fix this, we OR in vcpu->arch.doorbell_request when reading the
DPDES value.
Cc: stable@vger.kernel.org # v4.13+
Fixes: 579006944e0d ("KVM: PPC: Book3S HV: Virtualize doorbell facility on POWER9")
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
| -rw-r--r-- | arch/powerpc/kvm/book3s_hv.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 36d72e9faddfb..f8975c620f41c 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1678,7 +1678,14 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id, *val = get_reg_val(id, vcpu->arch.pspb); break; case KVM_REG_PPC_DPDES: - *val = get_reg_val(id, vcpu->arch.vcore->dpdes); + /* + * On POWER9, where we are emulating msgsndp etc., + * we return 1 bit for each vcpu, which can come from + * either vcore->dpdes or doorbell_request. + * On POWER8, doorbell_request is 0. + */ + *val = get_reg_val(id, vcpu->arch.vcore->dpdes | + vcpu->arch.doorbell_request); break; case KVM_REG_PPC_VTB: *val = get_reg_val(id, vcpu->arch.vcore->vtb); |