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nvme/pcie: dont initiate hotremoval on SIGBUS for VFIO devices

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This is an attempt to workaround a kernel data race spotted in #1275.
We have to delay our VFIO interraction until after the kernel handles
the PCIe hotremoval. Otherwise we risk having a deadlock inside the
kernel. We could put a dummy delay in SPDK hotremove routine, but we
don't know exactly how long we have to wait, so wait for the VFIO
hotremove notification to arrive instead. From what I understand it
is always sent after the kerner already releases the critical locks.

This patch breaks hotremove for VFIO devices when running with
DPDK version < 18.05, but those reached EOL already and their support
is removed from SPDK later within this series.

It would be nice to wait for this VFIO notification inside lib/env_dpdk
e.g. inside the detach function, but we don't know there why the
detach is happening. It could be triggered by a user RPC, not physical
device hotremoval.

Change-Id: I2727de923bb2e3e05a83202465330a32a77d7cfc
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/1732
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
This commit is contained in:
Darek Stojaczyk 2020-04-07 15:24:12 +02:00 committed by Jim Harris
parent f280ce59b7
commit 64c4fafd32
1 changed files with 9 additions and 16 deletions
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23
lib/nvme/nvme_pcie.c
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@ -269,8 +269,6 @@ _nvme_pcie_hotplug_monitor(struct spdk_nvme_probe_ctx *probe_ctx)
struct spdk_nvme_ctrlr *ctrlr, *tmp;
struct spdk_uevent event;
struct spdk_pci_addr pci_addr;
union spdk_nvme_csts_register csts;
struct spdk_nvme_ctrlr_process *proc;
if (g_spdk_nvme_driver->hotplug_fd < 0) {
return 0;
@ -313,26 +311,21 @@ _nvme_pcie_hotplug_monitor(struct spdk_nvme_probe_ctx *probe_ctx)
}
}
/* This is a work around for vfio-attached device hot remove detection. */
/* Initiate removal of physically hotremoved PCI controllers. Even after
* they're hotremoved from the system, SPDK might still report them via RPC.
*/
TAILQ_FOREACH_SAFE(ctrlr, &g_spdk_nvme_driver->shared_attached_ctrlrs, tailq, tmp) {
bool do_remove = false;
struct nvme_pcie_ctrlr *pctrlr;
if (ctrlr->trid.trtype == SPDK_NVME_TRANSPORT_PCIE) {
struct nvme_pcie_ctrlr *pctrlr = nvme_pcie_ctrlr(ctrlr);
if (ctrlr->trid.trtype != SPDK_NVME_TRANSPORT_PCIE) {
continue;
}
pctrlr = nvme_pcie_ctrlr(ctrlr);
if (spdk_pci_device_is_removed(pctrlr->devhandle)) {
do_remove = true;
}
}
/* NVMe controller BAR must be mapped in the current process before any access. */
proc = nvme_ctrlr_get_current_process(ctrlr);
if (proc) {
csts = spdk_nvme_ctrlr_get_regs_csts(ctrlr);
if (csts.raw == 0xffffffffU) {
do_remove = true;
}
}
if (do_remove) {
nvme_ctrlr_fail(ctrlr, true);