Messages in this thread | | | Subject | Re: [PATCH] PCI: designware: add a check of msi_desc in irqchip | From | Cao Zou <> | Date | Mon, 18 Dec 2017 10:02:20 +0800 |
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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@windriver.com wrote: >>> From: Zou Cao <cao.zou@windriver.com> >>> >>> 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@windriver.com> >>> --- >>> 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 2001 > From: Marc Zyngier <marc.zyngier@arm.com> > 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@arm.com> > --- > 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.
Regards, czou
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