Patch for stable 5.4 and below

Patch for stable 5.4 and below

[Juergen Gross]

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Hi Greg,

please add the attached patch to the stable kernels 5.4 and below.
It is a backport of upstream commit 4ba50e7c423c29639878c005732
which already went into 5.10 and 5.12.


Juergen

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From 4ba50e7c423c29639878c00573288869aa627068 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Tue, 18 May 2021 18:13:42 +0200
Subject: [PATCH] xen-pciback: redo VF placement in the virtual topology

The commit referenced below was incomplete: It merely affected what
would get written to the vdev-<N> xenstore node. The guest would still
find the function at the original function number as long as
__xen_pcibk_get_pci_dev() wouldn't be in sync. The same goes for AER wrt
__xen_pcibk_get_pcifront_dev().

Undo overriding the function to zero and instead make sure that VFs at
function zero remain alone in their slot. This has the added benefit of
improving overall capacity, considering that there's only a total of 32
slots available right now (PCI segment and bus can both only ever be
zero at present).

This is upstream commit 4ba50e7c423c29639878c00573288869aa627068.

Fixes: 8a5248fe10b1 ("xen PV passthru: assign SR-IOV virtual functions to 
separate virtual slots")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/8def783b-404c-3452-196d-3f3fd4d72c9e@suse.com
Signed-off-by: Juergen Gross <jgross@suse.com>
---
This is a backport for stable-5.4 and below.
---
 drivers/xen/xen-pciback/vpci.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/xen/xen-pciback/vpci.c b/drivers/xen/xen-pciback/vpci.c
index 4162d0e7e00d..cc7450f2b2a9 100644
--- a/drivers/xen/xen-pciback/vpci.c
+++ b/drivers/xen/xen-pciback/vpci.c
@@ -69,7 +69,7 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
 				   struct pci_dev *dev, int devid,
 				   publish_pci_dev_cb publish_cb)
 {
-	int err = 0, slot, func = -1;
+	int err = 0, slot, func = PCI_FUNC(dev->devfn);
 	struct pci_dev_entry *t, *dev_entry;
 	struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
 
@@ -94,23 +94,26 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
 
 	/*
 	 * Keep multi-function devices together on the virtual PCI bus, except
-	 * virtual functions.
+	 * that we want to keep virtual functions at func 0 on their own. They
+	 * aren't multi-function devices and hence their presence at func 0
+	 * may cause guests to not scan the other functions.
 	 */
-	if (!dev->is_virtfn) {
+	if (!dev->is_virtfn || func) {
 		for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 			if (list_empty(&vpci_dev->dev_list[slot]))
 				continue;
 
 			t = list_entry(list_first(&vpci_dev->dev_list[slot]),
 				       struct pci_dev_entry, list);
+			if (t->dev->is_virtfn && !PCI_FUNC(t->dev->devfn))
+				continue;
 
 			if (match_slot(dev, t->dev)) {
 				pr_info("vpci: %s: assign to virtual slot %d func %d\n",
 					pci_name(dev), slot,
-					PCI_FUNC(dev->devfn));
+					func);
 				list_add_tail(&dev_entry->list,
 					      &vpci_dev->dev_list[slot]);
-				func = PCI_FUNC(dev->devfn);
 				goto unlock;
 			}
 		}
@@ -123,7 +126,6 @@ static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
 				pci_name(dev), slot);
 			list_add_tail(&dev_entry->list,
 				      &vpci_dev->dev_list[slot]);
-			func = dev->is_virtfn ? 0 : PCI_FUNC(dev->devfn);
 			goto unlock;
 		}
 	}
-- 
2.26.2


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Re: Patch for stable 5.4 and below

[Greg Kroah-Hartman]

On Tue, Jun 01, 2021 at 03:22:09PM +0200, Juergen Gross wrote:
> Hi Greg,
> 
> please add the attached patch to the stable kernels 5.4 and below.
> It is a backport of upstream commit 4ba50e7c423c29639878c005732
> which already went into 5.10 and 5.12.

Now queued up, thanks.

greg k-h