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| 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 /arch/x86/kernel/kvm.c | |
| parent | d28eafc5a64045c78136162af9d4ba42f8230080 (diff) | |
KVM: PPC: Book3S HV: Don't lose pending doorbell request on migration on P9
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>
Diffstat (limited to 'arch/x86/kernel/kvm.c')
0 files changed, 0 insertions, 0 deletions