From: Oliver O'Halloran oohall@gmail.com
[ Upstream commit 3b5b9997b331e77ce967eba2c4bc80dc3134a7fe ]
On pseries there is a bug with adding hotplugged devices to an IOMMU group. For a number of dumb reasons fixing that bug first requires re-working how VFs are configured on PowerNV. For background, on PowerNV we use the pcibios_sriov_enable() hook to do two things:
1. Create a pci_dn structure for each of the VFs, and 2. Configure the PHB's internal BARs so the MMIO range for each VF maps to a unique PE.
Roughly speaking a PE is the hardware counterpart to a Linux IOMMU group since all the devices in a PE share the same IOMMU table. A PE also defines the set of devices that should be isolated in response to a PCI error (i.e. bad DMA, UR/CA, AER events, etc). When isolated all MMIO and DMA traffic to and from devicein the PE is blocked by the root complex until the PE is recovered by the OS.
The requirement to block MMIO causes a giant headache because the P8 PHB generally uses a fixed mapping between MMIO addresses and PEs. As a result we need to delay configuring the IOMMU groups for device until after MMIO resources are assigned. For physical devices (i.e. non-VFs) the PE assignment is done in pcibios_setup_bridge() which is called immediately after the MMIO resources for downstream devices (and the bridge's windows) are assigned. For VFs the setup is more complicated because:
a) pcibios_setup_bridge() is not called again when VFs are activated, and b) The pci_dev for VFs are created by generic code which runs after pcibios_sriov_enable() is called.
The work around for this is a two step process:
1. A fixup in pcibios_add_device() is used to initialised the cached pe_number in pci_dn, then 2. A bus notifier then adds the device to the IOMMU group for the PE specified in pci_dn->pe_number.
A side effect fixing the pseries bug mentioned in the first paragraph is moving the fixup out of pcibios_add_device() and into pcibios_bus_add_device(), which is called much later. This results in step 2. failing because pci_dn->pe_number won't be initialised when the bus notifier is run.
We can fix this by removing the need for the fixup. The PE for a VF is known before the VF is even scanned so we can initialise pci_dn->pe_number pcibios_sriov_enable() instead. Unfortunately, moving the initialisation causes two problems:
1. We trip the WARN_ON() in the current fixup code, and 2. The EEH core clears pdn->pe_number when recovering a VF and relies on the fixup to correctly re-set it.
The only justification for either of these is a comment in eeh_rmv_device() suggesting that pdn->pe_number *must* be set to IODA_INVALID_PE in order for the VF to be scanned. However, this comment appears to have no basis in reality. Both bugs can be fixed by just deleting the code.
Tested-by: Alexey Kardashevskiy aik@ozlabs.ru Reviewed-by: Alexey Kardashevskiy aik@ozlabs.ru Signed-off-by: Oliver O'Halloran oohall@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20191028085424.12006-1-oohall@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/kernel/eeh_driver.c | 6 ------ arch/powerpc/platforms/powernv/pci-ioda.c | 19 +++++++++++++++---- arch/powerpc/platforms/powernv/pci.c | 4 ---- 3 files changed, 15 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c index af1f3d5f9a0f7..377d23f58197a 100644 --- a/arch/powerpc/kernel/eeh_driver.c +++ b/arch/powerpc/kernel/eeh_driver.c @@ -554,12 +554,6 @@ static void *eeh_rmv_device(struct eeh_dev *edev, void *userdata)
pci_iov_remove_virtfn(edev->physfn, pdn->vf_index); edev->pdev = NULL; - - /* - * We have to set the VF PE number to invalid one, which is - * required to plug the VF successfully. - */ - pdn->pe_number = IODA_INVALID_PE; #endif if (rmv_data) list_add(&edev->rmv_list, &rmv_data->edev_list); diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c index ee63749a2d47e..28adfe4dd04c5 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda.c +++ b/arch/powerpc/platforms/powernv/pci-ioda.c @@ -1552,6 +1552,10 @@ static void pnv_ioda_setup_vf_PE(struct pci_dev *pdev, u16 num_vfs)
/* Reserve PE for each VF */ for (vf_index = 0; vf_index < num_vfs; vf_index++) { + int vf_devfn = pci_iov_virtfn_devfn(pdev, vf_index); + int vf_bus = pci_iov_virtfn_bus(pdev, vf_index); + struct pci_dn *vf_pdn; + if (pdn->m64_single_mode) pe_num = pdn->pe_num_map[vf_index]; else @@ -1564,13 +1568,11 @@ static void pnv_ioda_setup_vf_PE(struct pci_dev *pdev, u16 num_vfs) pe->pbus = NULL; pe->parent_dev = pdev; pe->mve_number = -1; - pe->rid = (pci_iov_virtfn_bus(pdev, vf_index) << 8) | - pci_iov_virtfn_devfn(pdev, vf_index); + pe->rid = (vf_bus << 8) | vf_devfn;
pe_info(pe, "VF %04d:%02d:%02d.%d associated with PE#%x\n", hose->global_number, pdev->bus->number, - PCI_SLOT(pci_iov_virtfn_devfn(pdev, vf_index)), - PCI_FUNC(pci_iov_virtfn_devfn(pdev, vf_index)), pe_num); + PCI_SLOT(vf_devfn), PCI_FUNC(vf_devfn), pe_num);
if (pnv_ioda_configure_pe(phb, pe)) { /* XXX What do we do here ? */ @@ -1584,6 +1586,15 @@ static void pnv_ioda_setup_vf_PE(struct pci_dev *pdev, u16 num_vfs) list_add_tail(&pe->list, &phb->ioda.pe_list); mutex_unlock(&phb->ioda.pe_list_mutex);
+ /* associate this pe to it's pdn */ + list_for_each_entry(vf_pdn, &pdn->parent->child_list, list) { + if (vf_pdn->busno == vf_bus && + vf_pdn->devfn == vf_devfn) { + vf_pdn->pe_number = pe_num; + break; + } + } + pnv_pci_ioda2_setup_dma_pe(phb, pe); } } diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c index c846300b78368..aa95b8e0f66ad 100644 --- a/arch/powerpc/platforms/powernv/pci.c +++ b/arch/powerpc/platforms/powernv/pci.c @@ -822,16 +822,12 @@ void pnv_pci_dma_dev_setup(struct pci_dev *pdev) struct pnv_phb *phb = hose->private_data; #ifdef CONFIG_PCI_IOV struct pnv_ioda_pe *pe; - struct pci_dn *pdn;
/* Fix the VF pdn PE number */ if (pdev->is_virtfn) { - pdn = pci_get_pdn(pdev); - WARN_ON(pdn->pe_number != IODA_INVALID_PE); list_for_each_entry(pe, &phb->ioda.pe_list, list) { if (pe->rid == ((pdev->bus->number << 8) | (pdev->devfn & 0xff))) { - pdn->pe_number = pe->pe_number; pe->pdev = pdev; break; }