On Thu, Oct 5, 2017 at 2:07 PM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > On Wed, Oct 04, 2017 at 04:29:14PM -0700, Alexander Duyck wrote: >> On Wed, Oct 4, 2017 at 4:01 PM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: >> > On Wed, Oct 04, 2017 at 08:52:58AM -0700, Tony Nguyen wrote: >> >> This fixes a bug that can occur if an AER error is encountered while SRIOV >> >> devices are present. >> >> >> >> This issue was seen by doing the following. Inject an AER error to a device >> >> that has SRIOV devices. After the device has recovered, remove the driver. >> >> Reload the driver and enable SRIOV which causes the following crash to >> >> occur: >> >> >> >> kernel BUG at drivers/pci/iov.c:157! >> >> invalid opcode: 0000 [#1] SMP >> >> CPU: 36 PID: 2295 Comm: bash Not tainted 4.14.0-rc1+ #74 >> >> Hardware name: Supermicro X9DAi/X9DAi, BIOS 3.0a 04/29/2014 >> >> task: ffff9fa41cd45a00 task.stack: ffffb4b2036e8000 >> >> RIP: 0010:pci_iov_add_virtfn+0x2eb/0x350 >> >> RSP: 0018:ffffb4b2036ebcb8 EFLAGS: 00010286 >> >> RAX: 00000000fffffff0 RBX: ffff9fa42c1c8800 RCX: ffff9fa421ce2388 >> >> RDX: 00000000df900000 RSI: ffff9fa8214fb388 RDI: 00000000df903fff >> >> RBP: ffffb4b2036ebd18 R08: ffff9fa421ce23b8 R09: ffffb4b2036ebc2c >> >> R10: ffff9fa42c1a5548 R11: 000000000000058e R12: ffff9fa8214fb000 >> >> R13: ffff9fa42c1a5000 R14: ffff9fa8214fb388 R15: 0000000000000000 >> >> FS: 00007f60724b6700(0000) GS:ffff9fa82f300000(0000) >> >> knlGS:0000000000000000 >> >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> >> CR2: 0000559eca8b0f40 CR3: 0000000864146000 CR4: 00000000001606e0 >> >> Call Trace: >> >> pci_enable_sriov+0x353/0x440 >> >> ixgbe_pci_sriov_configure+0xd5/0x1f0 [ixgbe] >> >> sriov_numvfs_store+0xf7/0x170 >> >> dev_attr_store+0x18/0x30 >> >> sysfs_kf_write+0x37/0x40 >> >> kernfs_fop_write+0x120/0x1b0 >> >> __vfs_write+0x37/0x170 >> >> ? __alloc_fd+0x3f/0x170 >> >> ? set_close_on_exec+0x30/0x70 >> >> vfs_write+0xb5/0x1a0 >> >> SyS_write+0x55/0xc0 >> >> entry_SYSCALL_64_fastpath+0x1a/0xa5 >> >> RIP: 0033:0x7f6071bafc20 >> >> RSP: 002b:00007ffe7d42ba48 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 >> >> RAX: ffffffffffffffda RBX: 0000559eca8b0f30 RCX: 00007f6071bafc20 >> >> RDX: 0000000000000002 RSI: 0000559eca961f60 RDI: 0000000000000001 >> >> RBP: 00007f6071e78ae0 R08: 00007f6071e7a740 R09: 00007f60724b6700 >> >> R10: 0000000000000073 R11: 0000000000000246 R12: 0000000000000000 >> >> R13: 0000000000000000 R14: 0000000000000000 R15: 0000559eca892170 >> >> RIP: pci_iov_add_virtfn+0x2eb/0x350 RSP: ffffb4b2036ebcb8 >> >> >> >> The occurs since during AER recovery the ARI Capable Hierarchy bit, >> >> which can affect the values for First VF Offset and VF Stride, is not set >> >> until after pci_iov_set_numvfs() is called. >> > >> > Can you elaborate on where exactly this happens? The only place we >> > explicitly set PCI_SRIOV_CTRL_ARI is in sriov_init(), which is only >> > called at enumeration-time. So I'm guessing you're talking about this >> > path: >> > >> > ixgbe_io_slot_reset >> > pci_restore_state >> > pci_restore_iov_state >> > sriov_restore_state >> > pci_iov_set_numvfs >> > >> > where we don't set PCI_SRIOV_CTRL_ARI at all. The fact that you say >> > PCI_SRIOV_CTRL_ARI isn't set until *after* pci_iov_set_numvfs() is >> > called suggests that it is being set *somewhere*, but I don't know >> > where. >> >> The ARI bit is initialized in sriov_init, stored in iov->ctrl, and >> restored in sriov_restore_state, but it occurs in the line after the >> call to pci_iov_set_numvfs. >> >> The problem is you don't want to write the full iov->ctrl value until >> after you have reset the the number of VFs since it will set VFE so >> pulling out and configuring the ARI value separately is needed. > > Doh, that should have been obvious to me ;) > >> >> This can cause the iov >> >> structure to be populated with values that are incorrect if the bit is >> >> later set. Check and set this bit, if needed, before calling >> >> pci_iov_set_numvfs() so that the values being populated properly take >> >> the ARI bit into account. >> >> >> >> CC: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> >> >> CC: Emil Tantilov <emil.s.tantilov@xxxxxxxxx> >> >> Signed-off-by: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx> >> >> --- >> >> drivers/pci/iov.c | 4 ++++ >> >> 1 file changed, 4 insertions(+) >> >> >> >> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c >> >> index 7492a65..a8896c7 100644 >> >> --- a/drivers/pci/iov.c >> >> +++ b/drivers/pci/iov.c >> >> @@ -497,6 +497,10 @@ static void sriov_restore_state(struct pci_dev *dev) >> >> if (ctrl & PCI_SRIOV_CTRL_VFE) >> >> return; >> >> >> >> + if ((iov->ctrl & PCI_SRIOV_CTRL_ARI) && !(ctrl & PCI_SRIOV_CTRL_ARI)) >> >> + pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, >> >> + ctrl | PCI_SRIOV_CTRL_ARI); > > This looks a little fiddly and also assumes that we only ever need to > *set* PCI_SRIOV_CTRL_ARI. That's likely the case because it's > probably cleared after reset and during resume. But I'm not *sure* > that's always the case, so what do you think about the proposal below? > >> >> for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) >> >> pci_update_resource(dev, i); >> >> > > > commit 95594dedd443e42ab0c16b9fba0109e955e7be13 > Author: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx> > Date: Wed Oct 4 08:52:58 2017 -0700 > > PCI: Restore "ARI Capable Hierarchy" before setting numVFs > > In the restore path, we previously read PCI_SRIOV_VF_OFFSET and > PCI_SRIOV_VF_STRIDE before restoring PCI_SRIOV_CTRL_ARI, which > affects the offset and stride: > > pci_restore_state > pci_restore_iov_state > sriov_restore_state > pci_iov_set_numvfs > pci_read_config_word(... PCI_SRIOV_VF_OFFSET, &iov->offset) > pci_write_config_word(... PCI_SRIOV_CTRL, iov->ctrl) > > The effect is that suspend/resume and AER recovery, which use > pci_restore_state(), may corrupt iov->offset and iov->stride. The iov > state is associated with the device, not the driver, so if we reload the > driver, it will use the the corrupted data, which may cause crashes like > this: > > kernel BUG at drivers/pci/iov.c:157! > RIP: 0010:pci_iov_add_virtfn+0x2eb/0x350 > Call Trace: > pci_enable_sriov+0x353/0x440 > ixgbe_pci_sriov_configure+0xd5/0x1f0 [ixgbe] > sriov_numvfs_store+0xf7/0x170 > dev_attr_store+0x18/0x30 > sysfs_kf_write+0x37/0x40 > kernfs_fop_write+0x120/0x1b0 > vfs_write+0xb5/0x1a0 > SyS_write+0x55/0xc0 > > The occurs since during AER recovery the ARI Capable Hierarchy bit, which > can affect the values for First VF Offset and VF Stride, is not set until > after pci_iov_set_numvfs() is called. This can cause the iov structure to > be populated with values that are incorrect if the bit is later set. > Check and set this bit, if needed, before calling pci_iov_set_numvfs() so > that the values being populated properly take the ARI bit into account. > > Signed-off-by: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx> > [bhelgaas: changelog, add comment, also clear ARI if necessary] > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > CC: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> > CC: Emil Tantilov <emil.s.tantilov@xxxxxxxxx> > > diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c > index ce24cf235f01..6bacb8995e96 100644 > --- a/drivers/pci/iov.c > +++ b/drivers/pci/iov.c > @@ -498,6 +498,14 @@ static void sriov_restore_state(struct pci_dev *dev) > if (ctrl & PCI_SRIOV_CTRL_VFE) > return; > > + /* > + * Restore PCI_SRIOV_CTRL_ARI before pci_iov_set_numvfs() because > + * it reads offset & stride, which depend on PCI_SRIOV_CTRL_ARI. > + */ > + ctrl &= ~PCI_SRIOV_CTRL_ARI; > + ctrl |= iov->ctrl & PCI_SRIOV_CTRL_ARI; > + pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, ctrl); > + > for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++) > pci_update_resource(dev, i); > I would think that should work. I don't see any issues since we have already verified in the previous line that VFE is cleared. Acked-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
