Subject: Re: [PATCH] PCI: Add parameter @mmio_force_on to pci_update_resource()

From: Gavin Shan <[email-masked]>
Date: Tue, 27 Sep 2016 09:43:36 +1000

On Mon, Sep 19, 2016 at 09:53:30AM +1000, Gavin Shan wrote:
>In pci_update_resource(), the PCI device's memory decoding (0x2 in
>PCI_COMMAND) is disabled when 64-bits memory BAR is updated if the
>PCI device's memory space wasn't asked to be always on by @pdev->
>mmio_always_on. The PF's memory decoding might be disabled when
>updating its IOV BARs in the following path. Actually, the PF's
>memory decoding shouldn't be disabled in this scenario as the PF
>has been started to provide services:
>
>   sriov_numvfs_store
>   pdev->driver->sriov_configure
>   mlx5_core_sriov_configure
>   pci_enable_sriov
>   sriov_enable
>   pcibios_sriov_enable
>   pnv_pci_sriov_enable
>   pnv_pci_vf_resource_shift
>   pci_update_resource
>
>This doesn't change the PF's memory decoding in the path by introducing
>additional parameter (@mmio_force_on) to pci_update_resource().
>
>Reported-by: Carol Soto <[email-masked]>
>Signed-off-by: Gavin Shan <[email-masked]>
>Tested-by: Carol Soto <[email-masked]>
>---

Bjorn, could you please have a quick review on this when you have available
time? We're running into SRIOV issue that is fixed by this patch.

Thanks,
Gavin 

> arch/powerpc/platforms/powernv/pci-ioda.c | 2 +-
> drivers/pci/iov.c                         | 2 +-
> drivers/pci/pci.c                         | 2 +-
> drivers/pci/setup-res.c                   | 9 +++++----
> include/linux/pci.h                       | 2 +-
> 5 files changed, 9 insertions(+), 8 deletions(-)
>
>diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
>index bc0c91e..2d6a2b7 100644
>--- a/arch/powerpc/platforms/powernv/pci-ioda.c
>+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
>@@ -999,7 +999,7 @@ static int pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
> 		dev_info(&dev->dev, "VF BAR%d: %pR shifted to %pR (%sabling %d VFs shifted by %d)\n",
> 			 i, &res2, res, (offset > 0) ? "En" : "Dis",
> 			 num_vfs, offset);
>-		pci_update_resource(dev, i + PCI_IOV_RESOURCES);
>+		pci_update_resource(dev, i + PCI_IOV_RESOURCES, true);
> 	}
> 	return 0;
> }
>diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
>index 2194b44..117aae6 100644
>--- a/drivers/pci/iov.c
>+++ b/drivers/pci/iov.c
>@@ -511,7 +511,7 @@ static void sriov_restore_state(struct pci_dev *dev)
> 		return;
>
> 	for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++)
>-		pci_update_resource(dev, i);
>+		pci_update_resource(dev, i, false);
>
> 	pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);
> 	pci_iov_set_numvfs(dev, iov->num_VFs);
>diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>index aab9d51..87a33c0 100644
>--- a/drivers/pci/pci.c
>+++ b/drivers/pci/pci.c
>@@ -545,7 +545,7 @@ static void pci_restore_bars(struct pci_dev *dev)
> 		return;
>
> 	for (i = 0; i < PCI_BRIDGE_RESOURCES; i++)
>-		pci_update_resource(dev, i);
>+		pci_update_resource(dev, i, false);
> }
>
> static const struct pci_platform_pm_ops *pci_platform_pm;
>diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
>index 66c4d8f..e8a50ff 100644
>--- a/drivers/pci/setup-res.c
>+++ b/drivers/pci/setup-res.c
>@@ -26,7 +26,7 @@
> #include "pci.h"
>
>
>-void pci_update_resource(struct pci_dev *dev, int resno)
>+void pci_update_resource(struct pci_dev *dev, int resno, bool mmio_force_on)
> {
> 	struct pci_bus_region region;
> 	bool disable;
>@@ -81,7 +81,8 @@ void pci_update_resource(struct pci_dev *dev, int resno)
> 	 * disable decoding so that a half-updated BAR won't conflict
> 	 * with another device.
> 	 */
>-	disable = (res->flags & IORESOURCE_MEM_64) && !dev->mmio_always_on;
>+	disable = (res->flags & IORESOURCE_MEM_64) &&
>+		  !mmio_force_on && !dev->mmio_always_on;
> 	if (disable) {
> 		pci_read_config_word(dev, PCI_COMMAND, &cmd);
> 		pci_write_config_word(dev, PCI_COMMAND,
>@@ -310,7 +311,7 @@ int pci_assign_resource(struct pci_dev *dev, int resno)
> 	res->flags &= ~IORESOURCE_STARTALIGN;
> 	dev_info(&dev->dev, "BAR %d: assigned %pR\n", resno, res);
> 	if (resno < PCI_BRIDGE_RESOURCES)
>-		pci_update_resource(dev, resno);
>+		pci_update_resource(dev, resno, false);
>
> 	return 0;
> }
>@@ -350,7 +351,7 @@ int pci_reassign_resource(struct pci_dev *dev, int resno, resource_size_t addsiz
> 	dev_info(&dev->dev, "BAR %d: reassigned %pR (expanded by %#llx)\n",
> 		 resno, res, (unsigned long long) addsize);
> 	if (resno < PCI_BRIDGE_RESOURCES)
>-		pci_update_resource(dev, resno);
>+		pci_update_resource(dev, resno, false);
>
> 	return 0;
> }
>diff --git a/include/linux/pci.h b/include/linux/pci.h
>index 0ab8359..99231d1 100644
>--- a/include/linux/pci.h
>+++ b/include/linux/pci.h
>@@ -1039,7 +1039,7 @@ int pci_try_reset_bus(struct pci_bus *bus);
> void pci_reset_secondary_bus(struct pci_dev *dev);
> void pcibios_reset_secondary_bus(struct pci_dev *dev);
> void pci_reset_bridge_secondary_bus(struct pci_dev *dev);
>-void pci_update_resource(struct pci_dev *dev, int resno);
>+void pci_update_resource(struct pci_dev *dev, int resno, bool mmio_force_on);
> int __must_check pci_assign_resource(struct pci_dev *dev, int i);
> int __must_check pci_reassign_resource(struct pci_dev *dev, int i, resource_size_t add_size, resource_size_t align);
> int pci_select_bars(struct pci_dev *dev, unsigned long flags);
>-- 
>2.1.0
>