[PATCH AUTOSEL 5.0 48/79] virtio_pci: fix a NULL pointer reference in vp_del_vqs

[PATCH AUTOSEL 5.0 48/79] virtio_pci: fix a NULL pointer reference in vp_del_vqs

[Sasha Levin]

From: Longpeng <longpeng2@huawei.com>

[ Upstream commit 6a8aae68c87349dbbcd46eac380bc43cdb98a13b ]

If the msix_affinity_masks is alloced failed, then we'll
try to free some resources in vp_free_vectors() that may
access it directly.

We met the following stack in our production:
[   29.296767] BUG: unable to handle kernel NULL pointer dereference at  (null)
[   29.311151] IP: [<ffffffffc04fe35a>] vp_free_vectors+0x6a/0x150 [virtio_pci]
[   29.324787] PGD 0
[   29.333224] Oops: 0000 [#1] SMP
[...]
[   29.425175] RIP: 0010:[<ffffffffc04fe35a>]  [<ffffffffc04fe35a>] vp_free_vectors+0x6a/0x150 [virtio_pci]
[   29.441405] RSP: 0018:ffff9a55c2dcfa10  EFLAGS: 00010206
[   29.453491] RAX: 0000000000000000 RBX: ffff9a55c322c400 RCX: 0000000000000000
[   29.467488] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9a55c322c400
[   29.481461] RBP: ffff9a55c2dcfa20 R08: 0000000000000000 R09: ffffc1b6806ff020
[   29.495427] R10: 0000000000000e95 R11: 0000000000aaaaaa R12: 0000000000000000
[   29.509414] R13: 0000000000010000 R14: ffff9a55bd2d9e98 R15: ffff9a55c322c400
[   29.523407] FS:  00007fdcba69f8c0(0000) GS:ffff9a55c2840000(0000) knlGS:0000000000000000
[   29.538472] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   29.551621] CR2: 0000000000000000 CR3: 000000003ce52000 CR4: 00000000003607a0
[   29.565886] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   29.580055] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   29.594122] Call Trace:
[   29.603446]  [<ffffffffc04fe8a2>] vp_request_msix_vectors+0xe2/0x260 [virtio_pci]
[   29.618017]  [<ffffffffc04fedc5>] vp_try_to_find_vqs+0x95/0x3b0 [virtio_pci]
[   29.632152]  [<ffffffffc04ff117>] vp_find_vqs+0x37/0xb0 [virtio_pci]
[   29.645582]  [<ffffffffc057bf63>] init_vq+0x153/0x260 [virtio_blk]
[   29.658831]  [<ffffffffc057c1e8>] virtblk_probe+0xe8/0x87f [virtio_blk]
[...]

Cc: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Longpeng <longpeng2@huawei.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/virtio/virtio_pci_common.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index d0584c040c60..7a0398bb84f7 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -255,9 +255,11 @@ void vp_del_vqs(struct virtio_device *vdev)
 	for (i = 0; i < vp_dev->msix_used_vectors; ++i)
 		free_irq(pci_irq_vector(vp_dev->pci_dev, i), vp_dev);
 
-	for (i = 0; i < vp_dev->msix_vectors; i++)
-		if (vp_dev->msix_affinity_masks[i])
-			free_cpumask_var(vp_dev->msix_affinity_masks[i]);
+	if (vp_dev->msix_affinity_masks) {
+		for (i = 0; i < vp_dev->msix_vectors; i++)
+			if (vp_dev->msix_affinity_masks[i])
+				free_cpumask_var(vp_dev->msix_affinity_masks[i]);
+	}
 
 	if (vp_dev->msix_enabled) {
 		/* Disable the vector used for configuration */
-- 
2.19.1

[PATCH AUTOSEL 5.0 65/79] virtio-blk: limit number of hw queues by nr_cpu_ids

[Sasha Levin]

From: Dongli Zhang <dongli.zhang@oracle.com>

[ Upstream commit bf348f9b78d413e75bb079462751a1d86b6de36c ]

When tag_set->nr_maps is 1, the block layer limits the number of hw queues
by nr_cpu_ids. No matter how many hw queues are used by virtio-blk, as it
has (tag_set->nr_maps == 1), it can use at most nr_cpu_ids hw queues.

In addition, specifically for pci scenario, when the 'num-queues' specified
by qemu is more than maxcpus, virtio-blk would not be able to allocate more
than maxcpus vectors in order to have a vector for each queue. As a result,
it falls back into MSI-X with one vector for config and one shared for
queues.

Considering above reasons, this patch limits the number of hw queues used
by virtio-blk by nr_cpu_ids.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/virtio_blk.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index b16a887bbd02..29bede887237 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -513,6 +513,8 @@ static int init_vq(struct virtio_blk *vblk)
 	if (err)
 		num_vqs = 1;
 
+	num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs);
+
 	vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL);
 	if (!vblk->vqs)
 		return -ENOMEM;
-- 
2.19.1