[+cc Alex, author of ffb0863426eb]
Please make your subject line match ffb0863426eb ("PCI: Disable
Samsung SM961/PM961 NVMe before FLR")
On Thu, Apr 29, 2021 at 06:07:30PM -0500, Robert Straw wrote:
> The SM951/PM951, when used in conjunction with the vfio-pci driver and
> passed to a KVM guest, can exhibit the fatal state addressed by the
> existing `nvme_disable_and_flr` quirk. If the guest cleanly shuts down
> the SSD, and vfio-pci attempts an FLR to the device while it is in this
> state, the nvme driver will fail when it attempts to bind to the device
> after the FLR due to the frozen config area, e.g:
>
> nvme nvme2: frozen state error detected, reset controller
> nvme nvme2: Removing after probe failure status: -12
>
> By including this older model (Samsung 950 PRO) of the controller in the
> existing quirk: the device is able to be cleanly reset after being used
> by a KVM guest.
I don't see anything in the PCIe spec about software being required to
do something special before initiating an FLR, so I assume this is a
hardware defect in the Samsung 950 PRO? Has Samsung published an
erratum or at least acknowledged it?
There's always the possibility that we are doing something wrong in
Linux *after* the FLR, e.g., not waiting long enough, not
reinitializing something correctly, etc.
> Signed-off-by: Robert Straw <drbawb@xxxxxxxxxxxxxxx>
> ---
> drivers/pci/quirks.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 653660e3b..e339ca238 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3920,6 +3920,7 @@ static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
> reset_ivb_igd },
> { PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IVB_M2_VGA,
> reset_ivb_igd },
> + { PCI_VENDOR_ID_SAMSUNG, 0xa802, nvme_disable_and_flr },
> { PCI_VENDOR_ID_SAMSUNG, 0xa804, nvme_disable_and_flr },
> { PCI_VENDOR_ID_INTEL, 0x0953, delay_250ms_after_flr },
> { PCI_VENDOR_ID_CHELSIO, PCI_ANY_ID,
> --
> 2.31.1
>
