lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 21 Jun 2016 11:26:56 +0800 From: Yongji Xie <xyjxie@...ux.vnet.ibm.com> To: Bjorn Helgaas <helgaas@...nel.org> Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-doc@...r.kernel.org, bhelgaas@...gle.com, alex.williamson@...hat.com, aik@...abs.ru, benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au, corbet@....net, warrier@...ux.vnet.ibm.com, zhong@...ux.vnet.ibm.com, nikunj@...ux.vnet.ibm.com, gwshan@...ux.vnet.ibm.com Subject: Re: [RESEND PATCH v2 3/4] PCI: Add a new option for resource_alignment to reassign alignment On 2016/6/21 9:57, Bjorn Helgaas wrote: > On Thu, Jun 02, 2016 at 01:46:50PM +0800, Yongji Xie wrote: >> When using resource_alignment kernel parameter, the current >> implement reassigns the alignment by changing resources' size >> which can potentially break some drivers. For example, the driver >> uses the size to locate some register whose length is related >> to the size. >> >> This patch adds a new option "noresize" for the parameter to >> solve this problem. > Why do we ever want to change the resource's size? I understand that > you want to change the resource's *alignment*, and that part makes > sense. But why change the *size*? Changing the resource size doesn't > change the hardware BAR size; it just means the struct resource will > describe a region larger than what the BAR actually claims. That > unnecessarily wastes space after the BAR. > > This was a problem with the code even before your patch; I'm > suggesting that if you have a way to change the alignment without > changing the resource size, maybe we should do that all the time. > Then you wouldn't need to add the "noresize" option. Yes, changing resource's size seems not a good idea. But would it break some existing systems which are using this kernel parameter if we remove the "noresize" option and change the alignment all the time? Thanks, Yongji >> Signed-off-by: Yongji Xie <xyjxie@...ux.vnet.ibm.com> >> --- >> Documentation/kernel-parameters.txt | 5 ++++- >> drivers/pci/pci.c | 35 +++++++++++++++++++++++++---------- >> 2 files changed, 29 insertions(+), 11 deletions(-) >> >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >> index 82b42c9..c4802f5 100644 >> --- a/Documentation/kernel-parameters.txt >> +++ b/Documentation/kernel-parameters.txt >> @@ -2997,13 +2997,16 @@ bytes respectively. Such letter suffixes can also be entirely omitted. >> window. The default value is 64 megabytes. >> resource_alignment= >> Format: >> - [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] >> + [<order of align>@][<domain>:]<bus>:<slot>.<func> >> + [:noresize][; ...] >> Specifies alignment and device to reassign >> aligned memory resources. >> If <order of align> is not specified, >> PAGE_SIZE is used as alignment. >> PCI-PCI bridge can be specified, if resource >> windows need to be expanded. >> + noresize: Don't change the resources' sizes when >> + reassigning alignment. >> ecrc= Enable/disable PCIe ECRC (transaction layer >> end-to-end CRC checking). >> bios: Use BIOS/firmware settings. This is the >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >> index a259394..3ee13e5 100644 >> --- a/drivers/pci/pci.c >> +++ b/drivers/pci/pci.c >> @@ -4748,11 +4748,13 @@ static DEFINE_SPINLOCK(resource_alignment_lock); >> /** >> * pci_specified_resource_alignment - get resource alignment specified by user. >> * @dev: the PCI device to get >> + * @resize: whether or not to change resources' size when reassigning alignment >> * >> * RETURNS: Resource alignment if it is specified. >> * Zero if it is not specified. >> */ >> -static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev) >> +static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev, >> + bool *resize) >> { >> int seg, bus, slot, func, align_order, count; >> resource_size_t align = 0; >> @@ -4786,6 +4788,11 @@ static resource_size_t pci_specified_resource_alignment(struct pci_dev *dev) >> } >> } >> p += count; >> + if (!strncmp(p, ":noresize", 9)) { >> + *resize = false; >> + p += 9; >> + } else >> + *resize = true; >> if (seg == pci_domain_nr(dev->bus) && >> bus == dev->bus->number && >> slot == PCI_SLOT(dev->devfn) && >> @@ -4818,11 +4825,12 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev) >> { >> int i; >> struct resource *r; >> + bool resize = true; >> resource_size_t align, size; >> u16 command; >> >> /* check if specified PCI is target device to reassign */ >> - align = pci_specified_resource_alignment(dev); >> + align = pci_specified_resource_alignment(dev, &resize); >> if (!align) >> return; >> >> @@ -4844,15 +4852,22 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev) >> if (!(r->flags & IORESOURCE_MEM)) >> continue; >> size = resource_size(r); >> - if (size < align) { >> - size = align; >> - dev_info(&dev->dev, >> - "Rounding up size of resource #%d to %#llx.\n", >> - i, (unsigned long long)size); >> + if (resize) { >> + if (size < align) { >> + size = align; >> + dev_info(&dev->dev, >> + "Rounding up size of resource #%d to %#llx.\n", >> + i, (unsigned long long)size); >> + } >> + r->flags |= IORESOURCE_UNSET; >> + r->end = size - 1; >> + r->start = 0; >> + } else { >> + r->flags &= ~IORESOURCE_SIZEALIGN; >> + r->flags |= IORESOURCE_STARTALIGN | IORESOURCE_UNSET; >> + r->start = max(align, size); >> + r->end = r->start + size - 1; >> } >> - r->flags |= IORESOURCE_UNSET; >> - r->end = size - 1; >> - r->start = 0; >> } >> /* Need to disable bridge's resource window, >> * to enable the kernel to reassign new resource >> -- >> 1.7.9.5 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-pci" in >> the body of a message to majordomo@...r.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists