On Thu, 2018-07-26 at 11:03 +0200, Cédric Le Goater wrote: > Ben, > > I have found out recently that the QEMU PowerNV could hang while accessing > the disk. > > The issue seems to be the phb3_msi_try_send() routine when called from > the resend() handler. The 'P' is ignored in that case but not the 'Q' > bit which means that no interrupt will be resent if P|Q are set.
I'd have to remember how PQ works on P8 ... my gut feeling is that we should resend if P=1 but I'm no 100% certain. > See the log extract below : > > PHB3(phb3_msi_try_send): MSI 0: try_send, ive=0x2005000000fd eff pq=0 > prio=5 server=8 ignore_p=0 > PHB3(phb3_msi_set_p): MSI 0: setting P > PHB3(phb3_msi_set_p): IVE readback: 0x2005010000fd > PHB3(phb3_msi_reject): MSI 0 rejected > PHB3(phb3_msi_resend): MSI resend... > PHB3(phb3_msi_try_send): MSI 0: try_send, ive=0x2005010000fd eff pq=0 > prio=5 server=8 ignore_p=1 > PHB3(phb3_msi_set_p): MSI 0: setting P > PHB3(phb3_msi_set_p): IVE readback: 0x2005010000fd > PHB3(phb3_msi_reject): MSI 0 rejected > PHB3(phb3_msi_try_send): MSI 0: try_send, ive=0x2005010000fd eff pq=2 > prio=5 server=8 ignore_p=0 > PHB3(phb3_msi_set_q): MSI 0: setting Q > PHB3(phb3_msi_set_q): IVE readback: 0x2005010100fd > PHB3(phb3_msi_resend): MSI resend... > PHB3(phb3_msi_try_send): MSI 0: try_send, ive=0x2005010100fd eff pq=1 > prio=5 server=8 ignore_p=1 > PHB3(phb3_msi_try_send): MSI 0: try_send, ive=0x2005010100fd eff pq=3 > prio=5 server=8 ignore_p=0 > PHB3(phb3_msi_try_send): MSI 0: try_send, ive=0x2005010100fd eff pq=3 > prio=5 server=8 ignore_p=0 > PHB3(phb3_msi_try_send): MSI 0: try_send, ive=0x2005010100fd eff pq=3 > prio=5 server=8 ignore_p=0 > PHB3(phb3_msi_try_send): MSI 0: try_send, ive=0x2005010100fd eff pq=3 > prio=5 server=8 ignore_p=0 > ... goes on and on ... > hangs > > I have added the relevant code at the bottom of the email. > > > If the 'Q' bit is ignored also, the results are good with a SATA drive > or a SCSI drive using the megasas model. Do you think this is correct ? > I would say so but I am still discovering that part. > > I have no idea why it didn't show up before. May be because we mostly > used virtio-blk. > > Thanks, > > C. > > > +static void phb3_msi_try_send(Phb3MsiState *msi, int srcno, bool ignore_p) > > +{ > > + ICSState *ics = ICS_BASE(msi); > > + uint64_t ive; > > + uint64_t server, prio, pq, gen; > > + > > + if (!phb3_msi_read_ive(msi->phb, srcno, &ive)) { > > + return; > > + } > > + > > + server = GETFIELD(IODA2_IVT_SERVER, ive); > > + prio = GETFIELD(IODA2_IVT_PRIORITY, ive); > > + pq = GETFIELD(IODA2_IVT_Q, ive); > > + if (!ignore_p) { > > + pq |= GETFIELD(IODA2_IVT_P, ive) << 1; > > + } > > + gen = GETFIELD(IODA2_IVT_GEN, ive); > > + > > + /* > > + * The low order 2 bits are the link pointer (Type II interrupts). > > + * Shift back to get a valid IRQ server. > > + */ > > + server >>= 2; > > + > > + switch (pq) { > > + case 0: /* 00 */ > > + if (prio == 0xff) { > > + /* Masked, set Q */ > > + phb3_msi_set_q(msi, srcno); > > + } else { > > + /* Enabled, set P and send */ > > + phb3_msi_set_p(msi, srcno, gen); > > + icp_irq(ics, server, srcno + ics->offset, prio); > > + } > > + break; > > + case 2: /* 10 */ > > + /* Already pending, set Q */ > > + phb3_msi_set_q(msi, srcno); > > + break; > > + case 1: /* 01 */ > > + case 3: /* 11 */ > > + default: > > + /* Just drop stuff if Q already set */ > > + break; > > + } > > +} > > + > > +static void phb3_msi_set_irq(void *opaque, int srcno, int val) > > +{ > > + Phb3MsiState *msi = PHB3_MSI(opaque); > > + > > + if (val) { > > + phb3_msi_try_send(msi, srcno, false); > > + } > > +} > > [ ... ] > > > +static void phb3_msi_resend(ICSState *ics) > > +{ > > + Phb3MsiState *msi = PHB3_MSI(ics); > > + unsigned int i, j; > > + > > + if (msi->rba_sum == 0) { > > + return; > > + } > > + > > + for (i = 0; i < 32; i++) { > > + if ((msi->rba_sum & (1u << i)) == 0) { > > + continue; > > + } > > + msi->rba_sum &= ~(1u << i); > > + for (j = 0; j < 64; j++) { > > + if ((msi->rba[i] & (1ull << j)) == 0) { > > + continue; > > + } > > + msi->rba[i] &= ~(1u << j); > > + phb3_msi_try_send(msi, i * 64 + j, true); > > + } > > + } > > +} > >