[RFC PATCH] riscv: Fix PCI warning by enabling PCI_MSI_ARCH_FALLBACKS

[Alexandre Ghiti]

When the interrupt controller is not using the IMSIC and ACPI is enabled,
the following warning appears:

[    0.866401] WARNING: CPU: 1 PID: 1 at drivers/pci/msi/msi.h:121 pci_msi_setup_msi_irqs+0x2c/0x32
[    0.867071] Modules linked in:
[    0.867389] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.13.0-rc2-00001-g795582ce7e24-dirty #44
[    0.867538] Hardware name: QEMU QEMU Virtual Machine, BIOS
[    0.867672] epc : pci_msi_setup_msi_irqs+0x2c/0x32
[    0.867738]  ra : __pci_enable_msix_range+0x30c/0x596
[    0.867783] epc : ffffffff8050af80 ra : ffffffff8050a66e sp : ff20000000023750
[    0.867809]  gp : ffffffff815153b0 tp : ff60000080108000 t0 : ff60000081109600
[    0.867833]  t1 : 0000000000000228 t2 : 0000000000000004 s0 : ff20000000023860
[    0.867857]  s1 : ff60000080de1000 a0 : ff60000080de1000 a1 : 0000000000000005
[    0.867880]  a2 : 0000000000000011 a3 : 0000000000000000 a4 : 0000000000000000
[    0.867902]  a5 : 0000000000000000 a6 : ff600000806368f0 a7 : fffffffffffffff0
[    0.867925]  s2 : 0000000000000005 s3 : ffffffffffffffff s4 : 0000000000000000
[    0.867948]  s5 : ff60000080de10c0 s6 : 0000000000000005 s7 : 0000000000000005
[    0.867970]  s8 : ff20000000023a08 s9 : ff600000811093c0 s10: 000000000000002c
[    0.867993]  s11: ff60000081109410 t3 : 0000000000000001 t4 : ff600000803a2878
[    0.868014]  t5 : 0000000000000004 t6 : ff60000080357450
[    0.868036] status: 0000000200000120 badaddr: ffffffff8050af80 cause: 0000000000000003
[    0.868186] [<ffffffff8050af80>] pci_msi_setup_msi_irqs+0x2c/0x32
[    0.868339] [<ffffffff80509172>] pci_alloc_irq_vectors_affinity+0xb8/0xe2
[    0.868362] [<ffffffff8059d62c>] vp_find_vqs_msix+0x12a/0x370
[    0.868385] [<ffffffff8059d8a0>] vp_find_vqs+0x2e/0x1de
[    0.868402] [<ffffffff8059bd80>] vp_modern_find_vqs+0x12/0x4e
[    0.868425] [<ffffffff80624a50>] init_vq+0x2b4/0x336
[    0.868448] [<ffffffff80624c36>] virtblk_probe+0xd4/0x90e
[    0.868469] [<ffffffff80594e02>] virtio_dev_probe+0x14a/0x1e6
[    0.868488] [<ffffffff805fe04c>] really_probe+0x86/0x234
[    0.868509] [<ffffffff805fe256>] __driver_probe_device+0x5c/0xda
[    0.868529] [<ffffffff805fe392>] driver_probe_device+0x2c/0xb2
[    0.868549] [<ffffffff805fe512>] __driver_attach+0x6c/0x11a
[    0.868569] [<ffffffff805fc17e>] bus_for_each_dev+0x60/0xae
[    0.868588] [<ffffffff805fda7c>] driver_attach+0x1a/0x22
[    0.868607] [<ffffffff805fd398>] bus_add_driver+0xce/0x1d6
[    0.868627] [<ffffffff805ff0b2>] driver_register+0x3e/0xd8
[    0.868647] [<ffffffff80594614>] __register_virtio_driver+0x1e/0x2c
[    0.868694] [<ffffffff80a31b82>] virtio_blk_init+0x6a/0x9e
[    0.868733] [<ffffffff8000f128>] do_one_initcall+0x58/0x194
[    0.868755] [<ffffffff80a011b0>] kernel_init_freeable+0x224/0x28e
[    0.868775] [<ffffffff809e4e48>] kernel_init+0x1e/0x13a
[    0.868795] [<ffffffff809ed952>] ret_from_fork+0xe/0x18

So enable PCI_MSI_ARCH_FALLBACKS to get rid of this.

Signed-off-by: Alexandre Ghiti <alexghiti at rivosinc.com>
---

This is an RFC as I'm really not sure this is the right fix,
Anup/Sunil/Thomas if you have any idea, please step in! Thanks

 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index d4a7ca0388c0..40d51feac2bb 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -199,6 +199,7 @@ config RISCV
 	select PCI_DOMAINS_GENERIC if PCI
 	select PCI_ECAM if (ACPI && PCI)
 	select PCI_MSI if PCI
+	select PCI_MSI_ARCH_FALLBACKS if PCI
 	select RISCV_ALTERNATIVE if !XIP_KERNEL
 	select RISCV_APLIC
 	select RISCV_IMSIC
-- 
2.39.2