net/mlx5: Ensure af_desc.mask is properly initialized

[    9.837087] mlx5_core 0000:02:00.0: firmware version: 16.35.2000
[    9.843126] mlx5_core 0000:02:00.0: 126.016 Gb/s available PCIe bandwidth (8.0 GT/s PCIe x16 link)
[   10.311515] mlx5_core 0000:02:00.0: Rate limit: 127 rates are supported, range: 0Mbps to 97656Mbps
[   10.321948] mlx5_core 0000:02:00.0: E-Switch: Total vports 2, per vport: max uc(128) max mc(2048)
[   10.344324] mlx5_core 0000:02:00.0: mlx5_pcie_event:301:(pid 88): PCIe slot advertised sufficient power (27W).
[   10.354339] BUG: unable to handle page fault for address: ffffffff8ff0ade0
[   10.361206] #PF: supervisor read access in kernel mode
[   10.366335] #PF: error_code(0x0000) - not-present page
[   10.371467] PGD 81ec39067 P4D 81ec39067 PUD 81ec3a063 PMD 114b07063 PTE 800ffff7e10f5062
[   10.379544] Oops: 0000 [#1] PREEMPT SMP PTI
[   10.383721] CPU: 0 PID: 117 Comm: kworker/0:6 Not tainted 6.3.0-13028-g7222f123c983 #1
[   10.391625] Hardware name: Supermicro X10SRA-F/X10SRA-F, BIOS 2.0b 06/12/2017
[   10.398750] Workqueue: events work_for_cpu_fn
[   10.403108] RIP: 0010:__bitmap_or+0x10/0x26
[   10.407286] Code: 85 c0 0f 95 c0 c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 89 c9 31 c0 48 83 c1 3f 48 c1 e9 06 39 c>
[   10.426024] RSP: 0000:ffffb45a0078f7b0 EFLAGS: 00010097
[   10.431240] RAX: 0000000000000000 RBX: ffffffff8ff0adc0 RCX: 0000000000000004
[   10.438365] RDX: ffff9156801967d0 RSI: ffffffff8ff0ade0 RDI: ffff9156801967b0
[   10.445489] RBP: ffffb45a0078f7e8 R08: 0000000000000030 R09: 0000000000000000
[   10.452613] R10: 0000000000000000 R11: 0000000000000000 R12: 00000000000000ec
[   10.459737] R13: ffffffff8ff0ade0 R14: 0000000000000001 R15: 0000000000000020
[   10.466862] FS:  0000000000000000(0000) GS:ffff9165bfc00000(0000) knlGS:0000000000000000
[   10.474936] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   10.480674] CR2: ffffffff8ff0ade0 CR3: 00000001011ae003 CR4: 00000000003706f0
[   10.487800] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   10.494922] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   10.502046] Call Trace:
[   10.504493]  <TASK>
[   10.506589]  ? matrix_alloc_area.constprop.0+0x43/0x9a
[   10.511729]  ? prepare_namespace+0x84/0x174
[   10.515914]  irq_matrix_reserve_managed+0x56/0x10c
[   10.520699]  x86_vector_alloc_irqs+0x1d2/0x31e
[   10.525146]  irq_domain_alloc_irqs_hierarchy+0x39/0x3f
[   10.530284]  irq_domain_alloc_irqs_parent+0x1a/0x2a
[   10.535155]  intel_irq_remapping_alloc+0x59/0x5e9
[   10.539859]  ? kmem_cache_debug_flags+0x11/0x26
[   10.544383]  ? __radix_tree_lookup+0x39/0xb9
[   10.548649]  irq_domain_alloc_irqs_hierarchy+0x39/0x3f
[   10.553779]  irq_domain_alloc_irqs_parent+0x1a/0x2a
[   10.558650]  msi_domain_alloc+0x8c/0x120
[   10.567697]  irq_domain_alloc_irqs_locked+0x11d/0x286
[   10.572741]  __irq_domain_alloc_irqs+0x72/0x93
[   10.577179]  __msi_domain_alloc_irqs+0x193/0x3f1
[   10.581789]  ? __xa_alloc+0xcf/0xe2
[   10.585273]  msi_domain_alloc_irq_at+0xa8/0xfe
[   10.589711]  pci_msix_alloc_irq_at+0x47/0x5c

The crash is due to matrix_alloc_area() attempting to access per-CPU
memory for CPUs that are not present on the system. The CPU mask
passed into reserve_managed_vector() via it's @irqd parameter is
corrupted because it contains uninitialized stack data.

Fixes: bbac70c7 ("net/mlx5: Use newer affinity descriptor")
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/pci_irq.c

@@ -571,11 +571,11 @@ int mlx5_irqs_request_vectors(struct mlx5_core_dev *dev, u16 *cpus, int nirqs,
 
 	af_desc.is_managed = false;
 	for (i = 0; i < nirqs; i++) {
+		cpumask_clear(&af_desc.mask);
 		cpumask_set_cpu(cpus[i], &af_desc.mask);
 		irq = mlx5_irq_request(dev, i + 1, &af_desc, rmap);
 		if (IS_ERR(irq))
 			break;
-		cpumask_clear(&af_desc.mask);
 		irqs[i] = irq;
 	}