Linux 7.3 Lands Last-Minute Fixes For Samsung 990 PRO & 990 EVO Plus SSDs

Ahead of the Linux 7.3 stable kernel expected to be released tomorrow, last minute workarounds were merged for the Samsung 990 PRO and Samsung 990 EVO Plus NVMe solid state drives. Coming by way of the Linux 7.3 PCI fixes pull, the Linux kernel will now ignore the Samsung 990 PRO and 990 EVO Plus NVMe SSDs from advertising their support for Immediate Readiness. PCIe 4.0 introduced the Immediate Readiness bit for indicating the drive can be instantly ready for handling configuration requests following a reset. This improves how quickly the OS can interact with an SSD following a reset. While Immediate Readiness is a nice feature, it turns out at least some firmware versions for the Samsung 990 PRO and 990 EVO Plus are advertising the feature without actually supporting it. That in turn is causing problems for Linux and also breaking VFIO pass-through for these drives. The fix now merged to Linux 7.3 Git explains: "The Samsung 990 PRO [144d:a80c] advertises Immediate Readiness, so pcie_flr() doesn't wait after FLR, but the drive returns ~0 for up to 7 ms. Since commit 10baa9b4df40 ("PCI: Drop unnecessary retries when restoring BARs"), the config restore after FLR is lost, which breaks VFIO passthrough of the drive. Firmware 8B2QJXD7 responds right after FLR, but older firmware such as 1B2QJXD7 doesn't, and the firmware version isn't visible here. [bhelgaas: The Samsung 990 EVO Plus [144d:a80d] with 2B2QKXG7 firmware seems to have the same problem.]" So by way of the PCI merge overnight, the issue is fixed in time for Linux 7.3 stable.