blob: 5a64fc4c8bdde4e1639923559a71da81f6dca438 [file] [log] [blame]
From 0df69dd0f893cc2440622dff0ef76a11ee1e8dc9 Mon Sep 17 00:00:00 2001
From: Oliver O'Halloran <>
Date: Mon, 28 Oct 2019 19:54:22 +1100
Subject: [PATCH] powerpc/powernv/iov: Ensure the pdn for VFs always contains a
valid PE number
commit 3b5b9997b331e77ce967eba2c4bc80dc3134a7fe upstream.
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 <>
Reviewed-by: Alexey Kardashevskiy <>
Signed-off-by: Oliver O'Halloran <>
Signed-off-by: Michael Ellerman <>
Signed-off-by: Paul Gortmaker <>
diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index fe0c32fb9f96..d147bc212405 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -540,12 +540,6 @@ 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;
if (rmv_data)
list_add(&edev->rmv_entry, &rmv_data->removed_vf_list);
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 0f72c7484824..295f47fb0578 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1556,6 +1556,10 @@ 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];
@@ -1568,13 +1572,11 @@ 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 ? */
@@ -1588,6 +1590,15 @@ static void pnv_ioda_setup_vf_PE(struct pci_dev *pdev, u16 num_vfs)
list_add_tail(&pe->list, &phb->ioda.pe_list);
+ /* 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 e43b996b7929..13ac322dcc47 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -816,16 +816,12 @@ void pnv_pci_dma_dev_setup(struct pci_dev *pdev)
struct pnv_phb *phb = hose->private_data;
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;