Hi lorenzo: What do you think? Regards, czou On 12/22/2017 05:35 PM, Marc Zyngier wrote:
On 22/12/17 07:38, Cao Zou wrote:On 12/22/2017 11:04 AM, Cao Zou wrote:On 12/20/2017 12:20 AM, Lorenzo Pieralisi wrote:On Mon, Dec 18, 2017 at 10:02:20AM +0800, Cao Zou wrote:On 12/16/2017 01:20 AM, Marc Zyngier wrote:On 15/12/17 16:17, Lorenzo Pieralisi wrote:[+Marc] On Thu, Dec 14, 2017 at 10:21:23AM +0800, cao.zou@xxxxxxxxxxxxx wrote:From: Zou Cao <cao.zou@xxxxxxxxxxxxx> When PCIE host setup, 32 MSI irq descriptions are created, but its msi_desc is NULL, msi_desc is bound in MSI irq requested by PCI device, normally just part of MSI are used, for others not used MSI irqs, its msi_desc is NULL, it is dangerous for MSI irq mask when MSI irq mask use the msi_desc to mask irq without checking, normally not used MSI irqs are never masked, it looks fine, but in some specified case, such as kdump, machine_kexec_mask_interrupts will force to mask these not used MSI irqs, than a crash will happen with NULL msi_desc. it is necessary to add check of msi_desc in irqchip, if we still bind the msi_desc only in irqs request and mask MSI irq by msi_desc. Add dwc_pci_msi_mask/unmask_irq, so we can get a chance to check the msi_desc. here is reproduced crash log in IMX7-SABER board with Intel 1030 PCI, when running kdump by "echo c > /proc/sysrq-trigger": sysrq: SysRq : Trigger a crash Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = 98ee1839 [00000000] *pgd=00000000 Internal error: Oops: 805 [#1] SMP ARM Modules linked in: CPU: 0 PID: 1370 Comm: sh Not tainted 4.15.0-rc3-00033-ga638349 #1 Hardware name: Freescale i.MX7 Dual (Device Tree) PC is at sysrq_handle_crash+0x50/0x98 LR is at sysrq_handle_crash+0x50/0x98 <snip> Backtrace: [<c047a15c>] (msi_set_mask_bit) from [<c047a1f0>] (pci_msi_mask_irq+0x14/0x18) [<c047a1dc>] (pci_msi_mask_irq) from [<c011142c>] (machine_crash_shutdown+0xd8/0x190) [<c0111354>] (machine_crash_shutdown) from [<c01b2924>] (__crash_kexec+0x5c/0xa0) [<c01b28c8>] (__crash_kexec) from [<c01b29dc>] (crash_kexec+0x74/0x80) [<c01b2968>] (crash_kexec) from [<c010cfa4>] (die+0x220/0x358) [<c010cd84>] (die) from [<c01169f0>] (__do_kernel_fault.part.0+0x5c/0x7c) [<c0116994>] (__do_kernel_fault.part.0) from [<c0116784>] (do_page_fault+0x2cc/0x37c) [<c01164b8>] (do_page_fault) from [<c0116970>] (do_translation_fault+0xb0/0xbc) [<c01168c0>] (do_translation_fault) from [<c010138c>] (do_DataAbort+0x3c/0xbc) [<c0101350>] (do_DataAbort) from [<c010d944>] (__dabt_svc+0x64/0xa0) Exception stack(0xec08bdf8 to 0xec08be40) bde0: 00000000 ec08be10 be00: 00000000 00000000 00000000 00000001 00000063 00000000 00000007 ec08a000 be20: 00000000 ec08be5c ec08be48 ec08be48 c04c46b8 c04c46b8 60060013 ffffffff [<c04c4668>] (sysrq_handle_crash) from [<c04c4900>] (__handle_sysrq+0xe0/0x254) [<c04c4820>] (__handle_sysrq) from [<c04c4aec>] (write_sysrq_trigger+0x78/0x90) [<c04c4a74>] (write_sysrq_trigger) from [<c029148c>] (proc_reg_write+0x68/0x90) [<c0291424>] (proc_reg_write) from [<c0229ef8>] (__vfs_write+0x34/0x12c) [<c0229ec4>] (__vfs_write) from [<c022a16c>] (vfs_write+0xa8/0x16c) [<c022a0c4>] (vfs_write) from [<c022a340>] (SyS_write+0x44/0x90) [<c022a2fc>] (SyS_write) from [<c0108220>] (ret_fast_syscall+0x0/0x28) Signed-off-by: Zou Cao <cao.zou@xxxxxxxxxxxxx> --- drivers/pci/dwc/pcie-designware-host.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c index 81e2157..485c4df 100644 --- a/drivers/pci/dwc/pcie-designware-host.c +++ b/drivers/pci/dwc/pcie-designware-host.c @@ -45,12 +45,28 @@ static int dw_pcie_wr_own_conf(struct pcie_port *pp, int where, int size, return dw_pcie_write(pci->dbi_base + where, size, val); } +static void dwc_pci_msi_mask_irq(struct irq_data *data) +{ + struct msi_desc *desc = irq_data_get_msi_desc(data); + + if (desc) + pci_msi_mask_irq(data); +} + +static void dwc_pci_msi_unmask_irq(struct irq_data *data) +{ + struct msi_desc *desc = irq_data_get_msi_desc(data); + + if (desc) + pci_msi_unmask_irq(data); +} + static struct irq_chip dw_msi_irq_chip = { .name = "PCI-MSI", - .irq_enable = pci_msi_unmask_irq, - .irq_disable = pci_msi_mask_irq, - .irq_mask = pci_msi_mask_irq, - .irq_unmask = pci_msi_unmask_irq, + .irq_enable = dwc_pci_msi_unmask_irq, + .irq_disable = dwc_pci_msi_mask_irq, + .irq_mask = dwc_pci_msi_mask_irq, + .irq_unmask = dwc_pci_msi_unmask_irq, };You have to CC me next time please. CC'ed Marc since he knows this code ways better than me and will help us find the right way of fixing it. I do not think that's a DWC-only problem - I see no reason why this would not affect other host bridges still relying on struct msi_controller (that we have to remove from the kernel). I do not think that this code is an actual fix but a plaster to paper over the issue - I will have a look into this as soon as possible to come up with an actual fix.Yeah, this looks mad. The problem is that this seems to allocate interrupts upfront, without being bound to an MSI. What could possibly go wrong? And that's definitely not the only one (pci-tegra.c is one fine example too). Until we take msi_controller and co to the backyard, how about the following:>From b4aa5d20ee7b716795ac875e180f564fe0f52de6 Mon Sep 17 00:00:00 2001From: Marc Zyngier <marc.zyngier@xxxxxxx> Date: Fri, 15 Dec 2017 17:10:14 +0000 Subject: [PATCH] PCI/MSI: Don't try to mask/unmask an MSI that doesn't have an msi_desc There are a lot of MSI drivers out there that preallocate their interrupts but not the corresponding MSIs. That's a prettty naughty behaviour. On a kexec crash, we try to shut down all the interrupts by calling the disable/mask methods. On these drivers, pci_msi_mask_irq() is unconditionnaly called, leading to a crash. You wanted a crash kernel, right? So let's paper over the issue for the time being by detecting the NULL msi_desc in msi_set_mask_bit(). Eventually, these drivers will have to be fixed... Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> --- drivers/pci/msi.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index e06607167858..a5042cc8f3fc 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -227,6 +227,9 @@ static void msi_set_mask_bit(struct irq_data *data, u32 flag) { struct msi_desc *desc = irq_data_get_msi_desc(data); + if (WARN_ONCE(!desc, "NULL MSI descriptor!")) + return; + if (desc->msi_attrib.is_msix) { msix_mask_irq(desc, flag); readl(desc->mask_base); /* Flush write to device */For "if (WARN_ONCE(!desc, "NULL MSI descriptor!")", it is a good way, just one problem. how to fix the kexec/kdump? this WARN_ONCE can tell the pci dirver to fix the MIS bound problem, but in kexec/kdump, it will force to mask all MSI, it means that there are a lot of WARNINGS when running kexec/kdump.There will be one warning as Marc said. Mind testing Marc's patch and reporting the result on the mailing list please if you want the issue fixed ? Thanks, LorenzoHi Lorenzo: Of course it can fix this issue, but warning will be seen in every time when running kdump root@nxp-imx7:~# echo c > /proc/sysrandom: crng init done sys/ sysrq-trigger sysvipc/ root@nxp-imx7:~# echo c > /proc/sysrq-trigger sysrq: SysRq : Trigger a crash Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = a9470000 [00000000] *pgd=a9474835, *pte=00000000, *ppte=00000000 Internal error: Oops: 817 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 369 Comm: sh Not tainted 4.12.14-yocto-standard+ #98 Hardware name: Freescale i.MX7 Dual (Device Tree) task: a86e5400 task.stack: a9438000 PC is at sysrq_handle_crash+0x30/0x3c LR is at sysrq_handle_crash+0x2c/0x3c pc : [<8059576c>] lr : [<80595768>] psr: 600e0013 sp : a9439eb8 ip : a9439eb8 fp : a9439ecc r10: 00000000 r9 : a9438000 r8 : 00000001 r7 : 00000000 r6 : 00000063 r5 : 00000007 r4 : 00000001 r3 : 00000000 r2 : a9439ea0 r1 : ab615434 r0 : 00000063 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 10c5387d Table: a947006a DAC: 00000051 Process sh (pid: 369, stack limit = 0xa9438210) Stack: (0xa9439eb8 to 0xa943a000) 9ea0: 8059573c 8106f41c 9ec0: a9439eec a9439ed0 80595968 80595748 00000002 a8451444 a8451400 00000000 9ee0: a9439f04 a9439ef0 80595a78 805958c4 a9439f78 a8451444 a9439f2c a9439f08 9f00: 802c570c 80595a1c 802c5698 00000000 00000002 001042a8 a9439f78 001042a8 9f20: a9439f44 a9439f30 80268078 802c56a4 a9439f78 a901d6c0 a9439f74 a9439f48 9f40: 80269598 8026805c 80286cac 80286c1c 00000000 00000000 a901d6c0 a901d6c0 9f60: 00000002 001042a8 a9439fa4 a9439f78 8026982c 802694e4 00000000 00000000 9f80: 00000002 001042a8 76f19da8 00000004 80107f68 00000000 00000000 a9439fa8 9fa0: 80107d60 802697ec 00000002 001042a8 00000001 001042a8 00000002 00000000 9fc0: 00000002 001042a8 76f19da8 00000004 00000002 00000002 00000000 00000000 9fe0: 00000444 7e9d4980 76e466f0 76e9e41c 600e0010 00000001 3dbfa0e8 a39746c6 [<8059576c>] (sysrq_handle_crash) from [<80595968>] (__handle_sysrq+0xb0/0x158) [<80595968>] (__handle_sysrq) from [<80595a78>] (write_sysrq_trigger+0x68/0x78) [<80595a78>] (write_sysrq_trigger) from [<802c570c>] (proc_reg_write+0x74/0xa4) [<802c570c>] (proc_reg_write) from [<80268078>] (__vfs_write+0x28/0x48) [<80268078>] (__vfs_write) from [<80269598>] (vfs_write+0xc0/0x164) [<80269598>] (vfs_write) from [<8026982c>] (SyS_write+0x4c/0x8c) [<8026982c>] (SyS_write) from [<80107d60>] (ret_fast_syscall+0x0/0x3c) Code: e5834000 f57ff04e ebee0bee e3a03000 (e5c34000) ------------[ cut here ]------------ WARNING: CPU: 0 PID: 369 at /export/disk1T/linux-yocto-4.12/drivers/pci/msi.c:230 msi_set_mask_bit+0x50/0xb0 NULL MSI descriptor! Modules linked in: CPU: 0 PID: 369 Comm: sh Not tainted 4.12.14-yocto-standard+ #98 Hardware name: Freescale i.MX7 Dual (Device Tree) [<80111a50>] (unwind_backtrace) from [<8010c110>] (show_stack+0x20/0x24) [<8010c110>] (show_stack) from [<804cb3dc>] (dump_stack+0x80/0xa0) [<804cb3dc>] (dump_stack) from [<8012a2f4>] (__warn+0xe4/0x114) [<8012a2f4>] (__warn) from [<8012a3f4>] (warn_slowpath_fmt+0x48/0x50) [<8012a3f4>] (warn_slowpath_fmt) from [<8052f380>] (msi_set_mask_bit+0x50/0xb0) [<8052f380>] (msi_set_mask_bit) from [<8052f41c>] (pci_msi_mask_irq+0x1c/0x20) [<8052f41c>] (pci_msi_mask_irq) from [<80110224>] (machine_crash_shutdown+0x108/0x174) [<80110224>] (machine_crash_shutdown) from [<801a7244>] (__crash_kexec+0x88/0xac) [<801a7244>] (__crash_kexec) from [<801a72d0>] (crash_kexec+0x68/0x78) [<801a72d0>] (crash_kexec) from [<8010c46c>] (die+0x358/0x47c) [<8010c46c>] (die) from [<8011ccbc>] (__do_kernel_fault.part.0+0x64/0x1f4) [<8011ccbc>] (__do_kernel_fault.part.0) from [<80ade250>] (do_page_fault+0x348/0x3d4) [<80ade250>] (do_page_fault) from [<801011f8>] (do_DataAbort+0x44/0xc4) [<801011f8>] (do_DataAbort) from [<80add5b8>] (__dabt_svc+0x58/0x80) Exception stack(0xa9439e68 to 0xa9439eb0) 9e60: 00000063 ab615434 a9439ea0 00000000 00000001 00000007 9e80: 00000063 00000000 00000001 a9438000 00000000 a9439ecc a9439eb8 a9439eb8 9ea0: 80595768 8059576c 600e0013 ffffffff [<80add5b8>] (__dabt_svc) from [<8059576c>] (sysrq_handle_crash+0x30/0x3c) [<8059576c>] (sysrq_handle_crash) from [<80595968>] (__handle_sysrq+0xb0/0x158) [<80595968>] (__handle_sysrq) from [<80595a78>] (write_sysrq_trigger+0x68/0x78) [<80595a78>] (write_sysrq_trigger) from [<802c570c>] (proc_reg_write+0x74/0xa4) [<802c570c>] (proc_reg_write) from [<80268078>] (__vfs_write+0x28/0x48) [<80268078>] (__vfs_write) from [<80269598>] (vfs_write+0xc0/0x164) [<80269598>] (vfs_write) from [<8026982c>] (SyS_write+0x4c/0x8c) [<8026982c>] (SyS_write) from [<80107d60>] (ret_fast_syscall+0x0/0x3c) ---[ end trace 7a853bb920d02801 ]--- Loading crashdump kernel... Bye! Booting Linux on physical CPU 0x0 Linux version 4.12.14-yocto-standard+ (czou@pek-czou-u14) (gcc version 4.7.3 20130226 (prerelease) (crosstool-NG linaro-1.13.1-4.7-2013.03-20130313 - Linaro GCC 2013.03) ) #98 SMP PREEMPT Fri Dec 22 10:59:43 CST7 CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=10c5387d CPU: div instructions available: patching division code CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache OF: fdt: Machine model: Freescale i.MX7 SabreSD Board OF: fdt: Ignoring memory range 0x80000000 - 0x88000000 Memory policy: Data cache writealloc OF: reserved mem: failed to allocate memory for node 'linux,cma' cma: Failed to reserve 320 MiB percpu: Embedded 17 pages/cpu @8fc75000 s38016 r8192 d23424 u69632 Built 1 zonelists in Zone order, mobility grouping on. Total pages: 64706 Kernel command line: console=ttymxc0,115200 root=/dev/nfs ip=dhcp nfsroot=128.224.162.234:/var/lib/tftp/nfs/rootfs_imx7wrl10,v3 maxcpus=1 elfcorehdr=0x9cf00000 mem=261120K PID hash table entries: 1024 (order: 0, 4096 bytes) Dentry cache hash table entries: 32768 (order: 5, 131072 bytes) Inode-cache hash table entries: 16384 (order: 4, 65536 bytes) Memory: 241716K/261120K available (10240K kernel code, 778K rwdata, 2388K rodata, 1024K init, 364K bss, 19404K reserved, 0K cma-reserved, 0K highmem) Virtual kernel memory layout: vector : 0xffff0000 - 0xffff1000 ( 4 kB) fixmap : 0xffc00000 - 0xfff00000 (3072 kB) vmalloc : 0x90000000 - 0xff800000 (1784 MB) lowmem : 0x80000000 - 0x8ff00000 ( 255 MB) pkmap : 0x7fe00000 - 0x80000000 ( 2 MB) Regards, czouHi Marc: I have a better way to fix it, just use dynamic allocate the irq_desc in MSI irq setup, remove the irq_desc allocate in dw_pcie_host_init, how do you think patch as follow: diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c index 5006d55..0426120 100644 --- a/drivers/pci/dwc/pcie-designware-host.c +++ b/drivers/pci/dwc/pcie-designware-host.c @@ -168,8 +168,12 @@ static int assign_irq(int no_irqs, struct msi_desc *desc, int *pos) goto no_valid_irq; irq = irq_find_mapping(pp->irq_domain, pos0); - if (!irq) - goto no_valid_irq; + + if (!irq) { + irq = irq_create_mapping(pp->irq_domain, pos0); + if (!irq) + goto no_valid_irq; + } /* * irq_create_mapping (called from dw_pcie_host_init) pre-allocates @@ -408,9 +412,6 @@ int dw_pcie_host_init(struct pcie_port *pp) ret = -ENXIO; goto error; } - - for (i = 0; i < MAX_MSI_IRQS; i++) - irq_create_mapping(pp->irq_domain, i); } else { ret = pp->ops->msi_host_init(pp, &dw_pcie_msi_chip); if (ret < 0)That's an option for *this* driver, but I'd rather you help Joao getting rid of this code altogether. It also ignores all the other drivers which suffer from the same defect. Joao, can you please point Cao to your existing patches? Thanks, M.
