Hi Robin, On Tue, Dec 19, 2017 at 04:34:46PM +0000, Robin Murphy wrote:
Hi Tomasz,
On 19/12/17 15:13, Tomasz Nowicki wrote:
Here is my lspci output of ThunderX2 for which I am observing kernel panic coming from SMMUv3 driver -> arm_smmu_write_strtab_ent() -> BUG_ON(ste_live):
# lspci -vt -[0000:00]-+-00.0-[01-1f]--+ [...] + [...] -00.0-[1e-1f]----00.0-[1f]----00.0 ASPEED Technology, Inc. ASPEED Graphics Family
ASP device -> 1f:00.0 VGA compatible controller: ASPEED Technology, Inc. ASPEED Graphics Family PCI-Express to PCI/PCI-X Bridge -> 1e:00.0 PCI bridge: ASPEED Technology, Inc. AST1150 PCI-to-PCI Bridge While setting up ASP device SID in IORT dirver: iort_iommu_configure() -> pci_for_each_dma_alias() we need to walk up and iterate over each device which alias transaction from downstream devices.
AST device (1f:00.0) gets BDF=0x1f00 and corresponding SID=0x1f00 from IORT. Bridge (1e:00.0) is the first alias. Following PCI Express to PCI/PCI-X Bridge spec: PCIe-to-PCI/X bridges alias transactions from downstream devices using the subordinate bus number. For bridge (1e:00.0), the subordinate is equal to 0x1f. This gives BDF=0x1f00 and SID=1f00 which is the same as downstream device. So it is possible to have two identical SIDs. The question is what we should do about such case. Presented patch prevents from registering the same ID so that SMMUv3 is not complaining later on.
Ooh, subtle :( There is logic in arm_smmu_attach_device() to tolerate grouped devices aliasing to the same ID, but I guess I overlooked the distinction of a device sharing an alias ID with itself. I'm not sure I really like trying to work around this in generic code, since fwspec->ids is essentially opaque data in a driver-specific format - in theory a driver is free to encode a single logical ID into multiple fwspec elements (I think I did that in an early draft of SMMUv2 SMR support), at which point this approach might corrupt things massively.
Does the (untested) diff below suffice?
Robin.
----->8-----diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index f122071688fd..d8a730d83401 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -1731,7 +1731,7 @@ static __le64 *arm_smmu_get_step_for_sid(struct arm_smmu_device *smmu, u32 sid)
static void arm_smmu_install_ste_for_dev(struct iommu_fwspec *fwspec) {
- int i;
- int i, j; struct arm_smmu_master_data *master = fwspec->iommu_priv; struct arm_smmu_device *smmu = master->smmu;
@@ -1739,6 +1739,13 @@ static void arm_smmu_install_ste_for_dev(struct iommu_fwspec *fwspec) u32 sid = fwspec->ids[i]; __le64 *step = arm_smmu_get_step_for_sid(smmu, sid);
/* Bridged PCI devices may end up with duplicated IDs */for (j = 0; j < i; j++)if (fwspec->ids[j] == sid)break;if (j < i)continue;- arm_smmu_write_strtab_ent(smmu, sid, step, &master->ste); }
}
Here is another tested by if you need one more: Tested-by: Jayachandran C. jnair@caviumnetworks.com
This fixes the crash below seen in ThunderX2 boards with Aspeed BMC (when booted without iommu.passthrough). Since this is a regression that breaks bootup on the platform, can you consider submitting this for the 4.15 cycle?
[ 84.729351] ------------[ cut here ]------------ [ 84.729354] kernel BUG at /home/ubuntu/linux/drivers/iommu/arm-smmu-v3.c:1201! [ 84.729358] Internal error: Oops - BUG: 0 [#1] SMP [ 84.729360] Modules linked in: ast(+) ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops qede(+) drm q ed bnx2x(+) mpt3sas raid_class scsi_transport_sas sdhci_acpi mdio sdhci libcrc32c gpio_xlp [ 84.729375] CPU: 190 PID: 1725 Comm: systemd-udevd Not tainted 4.15.0-rc5 #37 [ 84.729376] Hardware name: Cavium Inc. Unknown/Unknown, BIOS 1.0 11/08/2017 [ 84.729379] pstate: 80400009 (Nzcv daif +PAN -UAO) [ 84.729388] pc : arm_smmu_write_strtab_ent+0x1f0/0x1f8 [ 84.729391] lr : arm_smmu_install_ste_for_dev+0x70/0xc8 [ 84.729392] sp : ffff00001f6e3730 [ 84.729393] x29: ffff00001f6e3730 x28: ffff809ecc0d2268 [ 84.729395] x27: 0000000000000018 x26: ffff00001f6e3910 [ 84.729397] x25: ffff809ecc0d2238 x24: ffff809ecdc94158 [ 84.729398] x23: 0000000000000018 x22: 0000000000001d00 [ 84.729400] x21: ffff809ecdc90018 x20: ffff809ecb5ef288 [ 84.729401] x19: ffff80beca480000 x18: ffff0000093b8c08 [ 84.729402] x17: ffff000008aeab70 x16: ffff00001f6e3a20 [ 84.729404] x15: 0000000000000000 x14: dead000000000100 [ 84.729405] x13: dead000000000200 x12: 0000000000000020 [ 84.729407] x11: 0101010101010101 x10: 7f7f7f7f7f7f7f7f [ 84.729408] x9 : 0000000000000000 x8 : 0000000000000000 [ 84.729410] x7 : 0000000000000100 x6 : 0000000000000015 [ 84.729411] x5 : 0000000000000015 x4 : 0000000000000002 [ 84.729413] x3 : ffff809ecb5ef288 x2 : 0000000000000001 [ 84.729414] x1 : ffff000008691e30 x0 : ffff809ecc0d2238 [ 84.729418] Process systemd-udevd (pid: 1725, stack limit = 0x000000002c585821) [ 84.729420] Call trace: [ 84.729423] arm_smmu_write_strtab_ent+0x1f0/0x1f8 [ 84.729425] arm_smmu_install_ste_for_dev+0x70/0xc8 [ 84.729426] arm_smmu_attach_dev+0x100/0x2f8 [ 84.729431] __iommu_attach_device+0x54/0xe0 [ 84.729433] iommu_group_add_device+0x150/0x428 [ 84.729435] iommu_group_get_for_dev+0x84/0x180 [ 84.729436] arm_smmu_add_device+0x138/0x240 [ 84.729445] iort_iommu_configure+0x138/0x188 [ 84.729452] acpi_dma_configure+0x3c/0x80 [ 84.729456] dma_configure+0xb0/0xe0 [ 84.729462] driver_probe_device+0x1f0/0x4a8 [ 84.729464] __driver_attach+0x124/0x128 [ 84.729466] bus_for_each_dev+0x70/0xb0 [ 84.729467] driver_attach+0x30/0x40 [ 84.729469] bus_add_driver+0x248/0x2b8 [ 84.729471] driver_register+0x68/0x100 [ 84.729478] __pci_register_driver+0x5c/0x70 [ 84.729488] ast_init+0x30/0x1000 [ast] [ 84.729494] do_one_initcall+0x5c/0x168 [ 84.729501] do_init_module+0x64/0x1f4 [ 84.729502] load_module+0x1e64/0x21e8 [ 84.729503] SyS_finit_module+0x108/0x118 [ 84.729505] el0_svc_naked+0x20/0x24 [ 84.729508] Code: 34ffff82 d4210000 d2800120 17ffffd8 (d4210000)
Thanks, JC.