[v8] Error recovery for vfio-pci devices on s390x

[PATCH v8 4/9] PCI: Add additional checks for flr reset

Posted by Farhan Ali 2 weeks, 2 days ago

If a device is in an error state, then any reads of device registers can
return error value. Add addtional checks to validate if a device is in an
error state before doing an flr reset.

Cc: stable@vger.kernel.org
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
---
 drivers/pci/pci.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e7beaf1f65a7..2d0a4c7714af 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4358,12 +4358,19 @@ EXPORT_SYMBOL_GPL(pcie_flr);
  */
 int pcie_reset_flr(struct pci_dev *dev, bool probe)
 {
+	u32 reg;
+
 	if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
 		return -ENOTTY;
 
 	if (!(dev->devcap & PCI_EXP_DEVCAP_FLR))
 		return -ENOTTY;
 
+	if (pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &reg)) {
+		pci_warn(dev, "Device unable to do an FLR\n");
+		return -ENOTTY;
+	}
+
 	if (probe)
 		return 0;
 
-- 
2.43.0

Re: [PATCH v8 4/9] PCI: Add additional checks for flr reset

Posted by Julian Ruess 1 week, 6 days ago

On Thu Jan 22, 2026 at 8:44 PM CET, Farhan Ali wrote:
> If a device is in an error state, then any reads of device registers can
> return error value. Add addtional checks to validate if a device is in an

typo: additional

> error state before doing an flr reset.
>
> Cc: stable@vger.kernel.org
> Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
> Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
> ---
>  drivers/pci/pci.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e7beaf1f65a7..2d0a4c7714af 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4358,12 +4358,19 @@ EXPORT_SYMBOL_GPL(pcie_flr);
>   */
>  int pcie_reset_flr(struct pci_dev *dev, bool probe)
>  {
> +	u32 reg;
> +
>  	if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET)
>  		return -ENOTTY;
>  
>  	if (!(dev->devcap & PCI_EXP_DEVCAP_FLR))
>  		return -ENOTTY;
>  
> +	if (pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, &reg)) {
> +		pci_warn(dev, "Device unable to do an FLR\n");
> +		return -ENOTTY;
> +	}
> +
>  	if (probe)
>  		return 0;
>