Virtualization - Jul 2022 - [PATCH AUTOSEL 4.19 1/8] virtio_mmio: Add missing PM calls to freeze/restore

From: Stephan Gerhold <stephan.gerhold at kernkonzept.com>

[ Upstream commit ed7ac37fde33ccd84e4bd2b9363c191f925364c7 ]

Most virtio drivers provide freeze/restore callbacks to finish up
device usage before suspend and to reinitialize the virtio device after
resume. However, these callbacks are currently only called when using
virtio_pci. virtio_mmio does not have any PM ops defined.

This causes problems for example after suspend to disk (hibernation),
since the virtio devices might lose their state after the VMM is
restarted. Calling virtio_device_freeze()/restore() ensures that
the virtio devices are re-initialized correctly.

Fix this by implementing the dev_pm_ops for virtio_mmio,
similar to virtio_pci_common.

Signed-off-by: Stephan Gerhold <stephan.gerhold at kernkonzept.com>
Message-Id: <20220621110621.3638025-2-stephan.gerhold at kernkonzept.com>
Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/virtio/virtio_mmio.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index c69c755bf553..79474bd0c52c 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -66,6 +66,7 @@
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/pm.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/virtio.h>
@@ -508,6 +509,25 @@ static const struct virtio_config_ops
virtio_mmio_config_ops = {
 	.bus_name	= vm_bus_name,
 };
 
+#ifdef CONFIG_PM_SLEEP
+static int virtio_mmio_freeze(struct device *dev)
+{
+	struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
+
+	return virtio_device_freeze(&vm_dev->vdev);
+}
+
+static int virtio_mmio_restore(struct device *dev)
+{
+	struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
+
+	return virtio_device_restore(&vm_dev->vdev);
+}
+
+static const struct dev_pm_ops virtio_mmio_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(virtio_mmio_freeze, virtio_mmio_restore)
+};
+#endif
 
 static void virtio_mmio_release_dev(struct device *_d)
 {
@@ -761,6 +781,9 @@ static struct platform_driver virtio_mmio_driver = {
 		.name	= "virtio-mmio",
 		.of_match_table	= virtio_mmio_match,
 		.acpi_match_table = ACPI_PTR(virtio_mmio_acpi_match),
+#ifdef CONFIG_PM_SLEEP
+		.pm	= &virtio_mmio_pm_ops,
+#endif
 	},
 };
 
-- 
2.35.1

From: Stephan Gerhold <stephan.gerhold at kernkonzept.com>

[ Upstream commit e0c2ce8217955537dd5434baeba061f209797119 ]

Virtio devices might lose their state when the VMM is restarted
after a suspend to disk (hibernation) cycle. This means that the
guest page size register must be restored for the virtio_mmio legacy
interface, since otherwise the virtio queues are not functional.

This is particularly problematic for QEMU that currently still defaults
to using the legacy interface for virtio_mmio. Write the guest page
size register again in virtio_mmio_restore() to make legacy virtio_mmio
devices work correctly after hibernation.

Signed-off-by: Stephan Gerhold <stephan.gerhold at kernkonzept.com>
Message-Id: <20220621110621.3638025-3-stephan.gerhold at kernkonzept.com>
Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/virtio/virtio_mmio.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 79474bd0c52c..17cd682acc22 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -521,6 +521,9 @@ static int virtio_mmio_restore(struct device *dev)
 {
 	struct virtio_mmio_device *vm_dev = dev_get_drvdata(dev);
 
+	if (vm_dev->version == 1)
+		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
+
 	return virtio_device_restore(&vm_dev->vdev);
 }
 
-- 
2.35.1

From: Florian Westphal <fw at strlen.de>

[ Upstream commit c2577862eeb0be94f151f2f1fff662b028061b00 ]

When br_netfilter module is loaded, skbs may be diverted to the
ipv4/ipv6 hooks, just like as if we were routing.

Unfortunately, bridge filter hooks with priority 0 may be skipped
in this case.

Example:
1. an nftables bridge ruleset is loaded, with a prerouting
   hook that has priority 0.
2. interface is added to the bridge.
3. no tcp packet is ever seen by the bridge prerouting hook.
4. flush the ruleset
5. load the bridge ruleset again.
6. tcp packets are processed as expected.

After 1) the only registered hook is the bridge prerouting hook, but its
not called yet because the bridge hasn't been brought up yet.

After 2), hook order is:
   0 br_nf_pre_routing // br_netfilter internal hook
   0 chain bridge f prerouting // nftables bridge ruleset

The packet is diverted to br_nf_pre_routing.
If call-iptables is off, the nftables bridge ruleset is called as expected.

But if its enabled, br_nf_hook_thresh() will skip it because it assumes
that all 0-priority hooks had been called previously in bridge context.

To avoid this, check for the br_nf_pre_routing hook itself, we need to
resume directly after it, even if this hook has a priority of 0.

Unfortunately, this still results in different packet flow.
With this fix, the eval order after in 3) is:
1. br_nf_pre_routing
2. ip(6)tables (if enabled)
3. nftables bridge

but after 5 its the much saner:
1. nftables bridge
2. br_nf_pre_routing
3. ip(6)tables (if enabled)

Unfortunately I don't see a solution here:
It would be possible to move br_nf_pre_routing to a higher priority
so that it will be called later in the pipeline, but this also impacts
ebtables evaluation order, and would still result in this very ordering
problem for all nftables-bridge hooks with the same priority as the
br_nf_pre_routing one.

Searching back through the git history I don't think this has
ever behaved in any other way, hence, no fixes-tag.

Reported-by: Radim Hrazdil <rhrazdil at redhat.com>
Signed-off-by: Florian Westphal <fw at strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 net/bridge/br_netfilter_hooks.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 4b9d1d6bbf6f..55c7cdf5e7b8 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -1001,9 +1001,24 @@ int br_nf_hook_thresh(unsigned int hook, struct net *net,
 		return okfn(net, sk, skb);
 
 	ops = nf_hook_entries_get_hook_ops(e);
-	for (i = 0; i < e->num_hook_entries &&
-	      ops[i]->priority <= NF_BR_PRI_BRNF; i++)
-		;
+	for (i = 0; i < e->num_hook_entries; i++) {
+		/* These hooks have already been called */
+		if (ops[i]->priority < NF_BR_PRI_BRNF)
+			continue;
+
+		/* These hooks have not been called yet, run them. */
+		if (ops[i]->priority > NF_BR_PRI_BRNF)
+			break;
+
+		/* take a closer look at NF_BR_PRI_BRNF. */
+		if (ops[i]->hook == br_nf_pre_routing) {
+			/* This hook diverted the skb to this function,
+			 * hooks after this have not been run yet.
+			 */
+			i++;
+			break;
+		}
+	}
 
 	nf_hook_state_init(&state, hook, NFPROTO_BRIDGE, indev, outdev,
 			   sk, net, okfn);
-- 
2.35.1