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| author | Li Zhong <zhong@linux.vnet.ibm.com> | 2016-11-11 07:57:34 +0300 |
|---|---|---|
| committer | Paul Mackerras <paulus@ozlabs.org> | 2017-01-27 02:26:09 +0300 |
| commit | bf5a71d53835110d46d33eb5335713ffdbff9ab6 (patch) | |
| tree | 21f09dcc3174c68e861d1b433ee57d3c0cb4c4c4 /arch/powerpc/kvm/book3s_xics.c | |
| parent | 37451bc95dee0e666927d6ffdda302dbbaaae6fa (diff) | |
| download | linux-bf5a71d53835110d46d33eb5335713ffdbff9ab6.tar.xz | |
KVM: PPC: Book 3S: XICS: Fix potential issue with duplicate IRQ resends
It is possible that in the following order, one irq is resent twice:
CPU 1 CPU 2
ics_check_resend()
lock ics_lock
see resend set
unlock ics_lock
/* change affinity of the irq */
kvmppc_xics_set_xive()
write_xive()
lock ics_lock
see resend set
unlock ics_lock
icp_deliver_irq() /* resend */
icp_deliver_irq() /* resend again */
It doesn't have any user-visible effect at present, but needs to be avoided
when the following patch implementing the P/Q stuff is applied.
This patch clears the resend flag before releasing the ics lock, when we
know we will do a re-delivery after checking the flag, or setting the flag.
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Diffstat (limited to 'arch/powerpc/kvm/book3s_xics.c')
| -rw-r--r-- | arch/powerpc/kvm/book3s_xics.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/kvm/book3s_xics.c b/arch/powerpc/kvm/book3s_xics.c index debda779a240..cdfb4ed73601 100644 --- a/arch/powerpc/kvm/book3s_xics.c +++ b/arch/powerpc/kvm/book3s_xics.c @@ -125,6 +125,8 @@ static void ics_check_resend(struct kvmppc_xics *xics, struct kvmppc_ics *ics, if (!state->resend) continue; + state->resend = 0; + XICS_DBG("resend %#x prio %#x\n", state->number, state->priority); @@ -155,6 +157,7 @@ static bool write_xive(struct kvmppc_xics *xics, struct kvmppc_ics *ics, deliver = false; if ((state->masked_pending || state->resend) && priority != MASKED) { state->masked_pending = 0; + state->resend = 0; deliver = true; } @@ -488,6 +491,7 @@ static void icp_deliver_irq(struct kvmppc_xics *xics, struct kvmppc_icp *icp, */ smp_mb(); if (!icp->state.need_resend) { + state->resend = 0; arch_spin_unlock(&ics->lock); local_irq_restore(flags); goto again; |